WAS - SAO

$241 Find Cheap Flights from Washington, D.C. to Sao Paulo

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Washington, D.C. to Sao Paulo departing on 7/2. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy

KAYAK searches hundreds of travel sites at once for deals on flights to Sao Paulo

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Washington, D.C. to Sao Paulo.
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Washington, D.C. to Sao Paulo.
Travelers love KAYAK
41,299,237 searches in the past 7 days on KAYAK

Save 20% or moreCompare multiple travel sites with one search.

Track pricesNot ready to book? Create a price alert for when prices drop.

Bundle and saveSave money when you bundle your flight + hotel.

Filter your dealsChoose cabin class, free Wi-Fi and more.

Flights Deals
Useful Info
Flights Deals

Cheap Flights from Washington, D.C. to Sao Paulo (WAS-SAO)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Washington, D.C. to Sao Paulo that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Washington, D.C. to Sao Paulo

Wed, Jul 2 - Sun, Aug 24
Avianca Logo
3:25 pm - 3:20 pmIAD-GRU
22h 55m1 stop
Avianca Logo
7:20 am - 5:35 amGRU-IAD
23h 15m1 stop
$505Avianca
Find Deal
Wed, Jul 2 - Wed, Aug 20
Avianca Logo
3:25 pm - 3:20 pmIAD-GRU
22h 55m1 stop
Avianca Logo
7:20 am - 4:20 amGRU-IAD
22h 00m2 stops
$506Avianca
Find Deal
Fri, Sep 5 - Mon, Sep 8
Avianca Logo
3:25 pm - 5:35 amIAD-GRU
13h 10m1 stop
Avianca Logo
7:20 am - 4:20 amGRU-IAD
22h 00m2 stops
$507Avianca
Find Deal
Tue, Oct 21 - Tue, Nov 11
Copa Airlines Logo
4:34 pm - 6:30 amIAD-GRU
12h 56m1 stop
Copa Airlines Logo
11:11 am - 3:22 amGRU-IAD
18h 11m1 stop
$512Copa Airlines
Find Deal
Wed, Oct 22 - Mon, Oct 27
Copa Airlines Logo
2:25 am - 8:50 pmIAD-GRU
17h 25m1 stop
Copa Airlines Logo
3:07 am - 3:11 pmGRU-IAD
13h 04m1 stop
$532Copa Airlines
Find Deal
Thu, Aug 7 - Tue, Aug 12
LATAM Airlines Logo
6:59 am - 5:00 amDCA-GRU
21h 01m2 stops
LATAM Airlines Logo
4:35 pm - 9:11 amGRU-DCA
17h 36m2 stops
$592LATAM Airlines
Find Deal
Wed, Jun 25 - Tue, Jul 1
LATAM Airlines Logo
6:30 pm - 4:25 pmDCA-GRU
20h 55m2 stops
LATAM Airlines Logo
6:40 pm - 11:00 amGRU-DCA
17h 20m2 stops
$616LATAM Airlines
Find Deal
Sat, Jul 12 - Thu, Jul 31
Delta Logo
3:59 pm - 9:00 amDCA-GRU
16h 01m1 stop
Delta Logo
10:05 am - 11:42 pmGRU-DCA
14h 37m1 stop
$833Delta
Find Deal
Thu, Sep 11 - Sat, Sep 20
Delta Logo
1:45 pm - 5:40 amDCA-GRU
14h 55m2 stops
Delta Logo
11:05 pm - 2:39 pmGRU-DCA
16h 34m2 stops
$837Delta
Find Deal
Fri, Jul 18 - Fri, Jul 25
United Airlines Logo
6:00 am - 7:35 amDCA-GRU
24h 35m1 stop
United Airlines Logo
10:20 pm - 9:02 pmGRU-DCA
23h 42m1 stop
$936United Airlines
Find Deal
Useful Info

KAYAK's insights & trends for Washington, D.C. to Sao Paulo flights

Get data-powered insights and trends into flights from Washington, D.C. to Sao Paulo to help you find the cheapest flights, the best time to fly and much more.

What is the cheapest Washington, D.C. to Sao Paulo flight route?

The cheapest price for flight routes found by users searching on KAYAK in the last 2 weeks for round-trip flights from Washington, D.C. to Sao Paulo.

Our data shows that the cheapest route for a return flight from Washington, D.C. to Sao Paulo cost $609 and was between Washington, D.C. Dulles Intl Airport (IAD) and Sao Paulo Guarulhos Intl Airport (GRU). On average, the best prices are found if you fly this route. The average price for a return flight for this route is $609.

What’s the cheapest day of the week to fly from Washington, D.C. to Sao Paulo?

The average price of all round-trip flights from Washington, D.C. to Sao Paulo clicked on KAYAK for each day over the last 12 months.

If your flying dates are flexible, you should consider flying to Sao Paulo on a Wednesday, as we generally find the cheapest rates on that day for this route. On the other hand, Monday is the most expensive day to fly from Washington, D.C. to Sao Paulo. For your return ticket, we recommend flying on a Thursday and avoiding Sundays for the best deals.

What is the cheapest month to fly from Washington, D.C. to Sao Paulo?

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Washington, D.C. to Sao Paulo, removes the top 0.1% to account for outliers, and then takes the median of all values for each month.

The cheapest month for flights from Washington, D.C. to Sao Paulo is November, where tickets cost $618 (return) on average. On the other hand, the most expensive months are December and January, where the average cost of round-trip tickets is $1,282 and $923 respectively.

Can I save money by flying with a layover from Washington, D.C. to Sao Paulo?

The average round-trip price for all non-stop flights, flights with one layover, and flights with two layovers for the route found by users searching on KAYAK in the last 2 weeks.

No, with an average price for the route of $1,575, prices are generally cheapest when you fly direct.

Good to know

Low seasonSeptember
High seasonDecember
Cheapest flight$241
Best time to beat the crowds with an average 22% drop in price.
Most popular time to fly with an average 62% increase in price.
Flight from Washington Dulles Airport to Sao Paulo Guarulhos Airport

When to book flights from Washington, D.C. to Sao Paulo

Are your dates flexible? Find out the best times to travel from Washington, D.C. to Sao Paulo based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price
KAYAK looks at all historical flight data for each date to provide a predicted price for one-way trips or round-trips with a duration up to 40 days. While we try to provide actual minimum prices for each date, some prices are predictions and actual prices may differ.

FAQs for booking flights from Washington, D.C. to Sao Paulo

  • What is the luggage limit when flying from San Salvador to New York City with Copa Airlines?

    Economy Full and all Business class customers flying from Washington, D.C. to Sao Paulo on Copa Airlines are allowed two checked bags. However, some limitations must be taken into account. There is a 62-inch limit on your checked luggage's combined length and width. Bags for Economy passengers (Basic, Classic, and Full) are limited to 50 lbs in weight, while those traveling in Business Class (Promo and Full) are allowed up to 70 lbs.

  • Can passengers travel with infants from Washington, D.C., to Sao Paulo?

    From Washington D.C. to Sao Paulo, Avianca is a good option for passengers with infants. Avianca does not charge extra for children under the age of two who do not have their seats because they are considered infants. If the kid has a ticket, they can bring their bags and use the in-flight eating options. A crib is available upon request for your newborn.

  • Can I travel on LATAM Airlines with my pet from Washington, D.C., to Sao Paulo?

    When traveling from Washington, D.C., to Sao Paulo with LATAM Airlines along with your pet, rest assured that both you and your furry companion will arrive safely. LATAM Airlines allows pets to travel in Premium class and Economy cabins as long as sufficient space is available. It is essential to ensure that your pet complies with all travel regulations and is not sedated to provide a secure boarding process.

  • How can I travel from Sao Paulo-Guarulhos Airport (GRU) to the downtown area?

    The Airport Bus Service provides four daily bus departures from Terminal 2 of Guarulhos Airport to Praça da República, with a travel time of approximately 1 hour and 5 minutes. Another transportation option is the train, which offers a direct route to downtown, taking around 45 minutes. The CPTM-operated Line 13 (Jade) connects the "Engenheiro Goulart" station downtown with the "Aeroporto / Guarulhos" station at the airport.

  • What is the cheapest flight from Washington, D.C. to Sao Paulo?

    In the last 3 days, the lowest price for a flight from Washington, D.C. to Sao Paulo was $241 for a one-way ticket and $505 for a round-trip.

  • Do I need a passport to fly between Washington, D.C. and Sao Paulo?

    Yes

  • Which airports will I be using when flying from Washington, D.C. to Sao Paulo?

    Washington, D.C. has 2 major airports: Washington, D.C. Reagan-National and Washington, D.C. Dulles Intl. Sao Paulo is served by 3 airports: Sao Paulo Congonhas, Sao Paulo Guarulhos Intl, and Sao Paulo Viracopos. You’ll usually find the cheapest deals if you fly from Washington Dulles Airport and land at Sao Paulo Guarulhos Airport.

  • Which airlines offer Wi-Fi service onboard planes from Washington, D.C. to Sao Paulo?

    American Airlines, and Delta offer inflight Wi-Fi service on the Washington, D.C. to Sao Paulo flight route.

  • Which aircraft models fly most regularly from Washington, D.C. to Sao Paulo?

    The Boeing 767-400 is the aircraft model that flies most regularly on the Washington, D.C. to Sao Paulo flight route.

  • Which airline alliances offer flights from Washington, D.C. to Sao Paulo?

    Star Alliance is the only airline alliance operating flights between Washington, D.C. and Sao Paulo.

  • On which days can I fly direct from Washington, D.C. to Sao Paulo?

    There are nonstop flights from Washington, D.C. to Sao Paulo on a daily basis.

  • Which is the best airline for flights from Washington, D.C. to Sao Paulo, Delta or Azul?

    The two airlines most popular with KAYAK users for flights from Washington, D.C. to Sao Paulo are Delta and Azul. With an average price for the route of $759 and an overall rating of 8.0, Delta is the most popular choice. Azul is also a great choice for the route, with an average price of $1,777 and an overall rating of 8.0.

  • How does KAYAK find such low prices on flights from Washington, D.C. to Sao Paulo?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Washington, D.C. to Sao Paulo.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Washington, D.C. to Sao Paulo?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to Sao Paulo from Washington, D.C. is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Washington, D.C. to Sao Paulo?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly to Sao Paulo with an airline and back to Washington, D.C. with another airline.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Washington, D.C. to Sao Paulo?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying to Sao Paulo from Washington, D.C. up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

KAYAK’s top tips for finding a cheap flight from Washington, D.C. to Sao Paulo

  • Looking for a cheap flight? 25% of our users found flights on this route for $289 or less one-way and $684 or less round-trip.
  • If you have limited mobility and are traveling from Washington, D.C., to Sao Paulo, consider choosing ANA Airlines. ANA Airlines offers special assistance to passengers with mobility needs including providing wheelchairs and support throughout the flight. Accessible restrooms are available both at the terminal and on the aircraft, and passengers are welcome to bring any required assistive devices along for their journey.
  • Flying on Avianca from Washington, D.C. to Sao Paulo? The airline can cater to special dietary needs through its meal service. The Buy aboard option enables passengers to purchase a range of food and beverage choices, such as vegetarian and children's menus. Passengers with specific dietary restrictions can also bring their own light, pre-packaged meals on board the aircraft.
  • Passengers flying from Washington, D.C., to Sao Paulo have two options for arrival international airports to choose from: São Paulo-Guarulhos International Airport (GRU) and Viracopos - Campinas International Airport (VCP). If you prefer an airport closer to downtown Sao Paulo, it is recommended to select GRU as your arrival airport, as it is approximately 15 miles away, whereas VCP is about 56 miles from downtown Sao Paulo.
  • If you've already reserved a seat in Economy, you can still pay something extra to upgrade to Business or First Class and benefit from the extra space, food, and entertainment options available to make your long journey more manageable. Passengers on LATAM Airlines, Avianca, Copa, and many other airlines that service this route are informed of class upgrades.
  • São Paulo-Guarulhos Airport (GRU) is located near several cities in São Paulo state that passengers from Washington, D.C. can visit after their flight. The nearest major city is Guarulhos, home to the airport. Other nearby cities include São Paulo, São Bernardo do Campo, Santo André, and São Caetano do Sul, which are close to GRU Airport.

Prefer to fly direct from Washington, D.C. to Sao Paulo?

Find which airlines fly direct from Washington, D.C. to Sao Paulo, which days they fly and book direct flights.

Direct departures

Washington, D.C. to Sao Paulo

Monday

United Airlines

United Airlines

Tuesday

United Airlines

United Airlines

Wednesday

United Airlines

United Airlines

Thursday

United Airlines

United Airlines

Friday

United Airlines

United Airlines

Saturday

United Airlines

United Airlines

Sunday

United Airlines

United Airlines

See more direct flights

Direct returns

Sao Paulo to Washington, D.C.

Monday

United Airlines

United Airlines

Tuesday

United Airlines

United Airlines

Wednesday

United Airlines

United Airlines

Thursday

United Airlines

United Airlines

Friday

United Airlines

United Airlines

Saturday

United Airlines

United Airlines

Sunday

United Airlines

United Airlines

See more direct flights
See more direct flights

Top 5 airlines serving from Washington, D.C. to Sao Paulo

 
See real verified KAYAK customer reviews for airlines flying from Washington, D.C. to Sao Paulo. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from Washington, D.C. to Sao Paulo? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
8.0
DeltaOverall score based on 7950 reviews
7.9Entertainment
7.3Food
8.2Boarding
7.9Comfort
8.5Crew
Airline reviews

Great service. Flight was delayed while we sat on the runway for a couple of hours. Weather related. Staff made is very bearable. The steward servicing the first class cabin was exceptional. Thank you! 💗

10.0 ExcellentHartaj, Jun 2025EWR - RDU
Read more Delta reviews

Great service. Flight was delayed while we sat on the runway for a couple of hours. Weather related. Staff made is very bearable. The steward servicing the first class cabin was exceptional. Thank you! 💗

5 hours of delay that could've been much shorter if Delta had taken the 1 hour delay they imposed on the flight before boarding to run any of the plane checks required for flight to find the hydraulic issue that required nearly 3 hours to fix. $24 of meal credit buys a sandwich and a soft drink. Poor communication within the terminal about what gate we'd be re-boarding from and when we'd be re-boarding.

Great flight! Only complaint I had was that I didn’t get breakfast that morning because I don’t eat eggs for breakfast.. I ate an energy bar I bought in the airport which I had never done before. Otherwise, another great Delta flight!

Amazing flight! I have never noticed the uniforms of the attendants before in twenty years of flying except today when one female had the most amazing dress on. It was beautifully designed and showed she was in charge. I never dreamed I would google who designed Delta uniforms . The ultimate compliment is when another woman admires your outfit. . I hope your designer puts it on the market

It would be nice if was given wires ear buds. Overall was a good experience was able to sleep on the plane

My flight was 6 pm 6/6. Every hour they delayed it again - air condition issues then no pilot then the crew had worked too many hours and cancelled the flight at 11 pm. Sent customers to NJ a 45 minutes uber ride to a hotel. Had to be back by 5 am for a 7 am flight and again no pilot etc with another three hours of delays.

The entertainment and wifi mostly didn't work on this flight.

Terrible entertainment system - kept freezing and audio kept cutting out. Snacks were mediocre at best for a 5 hour flight.

The check in and bag drop off for Sky Priority members is slow. The Clear security was also slow - a TSA issue.

I am still upset that my bag was lost on a recent trip to Rome ; we were inconvenienced and out €150 Euros ; delta has refused to reimburse us

It was good, however the airplane was really cold. We received snacks and the crew was friendly.

Delta has an outstanding service. They are courteous and punctual most of the time. The flight departed a half hour late but we arrived 15 minutes early.

Not sure why there are so many security checks at this airport. Consistently annoying showing passport over and over, checking carryons at gate all the while trying to make tight connection. Basically it was uncomfortable crowded cabin with meidiocre service

Although the flight is goof and the crew is good, the way the airline charges you for every service is ridiculous.

Plane never left the ground. Mech issues - entire trip was rerouted through united.

No entertainment but not expected. Unless you are referring to monitor that you can use. Then Al, was fine on all flights.

Friendly staff, It was the first flight out for our plane, so had to be deiced from the frost. Only delayed a few minutes,

Staff encountered friendly and helpful. Flight delayed 1 hour due to mechanical issue, but made it through Atlanta immkgration and security in plenty of time,

We boarded so late it caused us to miss time at Foz. No real information was provided to the passengers waiting.

Basic experience, we were delayed causing less time to enjoy our destination and on the way back, we boarded when the flight should have been taking off.

Tell people to remain in their seats during the meal/beverage distribution. Enforce boarding by group numbers. No one was checking. Tell people to turn their electronics speakers off. Bigger cups for drinks.

Placed us in the last rear row of the plane so could not recline seats because of the rear wall, and also made it more of a tight space when the passenger in front reclined their seat. While understand seat assignments, every passenger should be afforded a reclining seat. The odor control scent from the restrooms was overwhelming strong. My wife and I could not deal with it, and she suffered a terrible headache as a result. I kept getting hit by the crew since I was on the ilse seat. No apologies, nothing. They made me feel like I was supposed to take the beating for a 3 hr flight.

There was no individual at the front check in when I arrived. I waited for at least 15 minutes and walked around asking security/janitors if they could help and they did not have a solution. So I had to take my checked bag through security and they threw away some of my items. I ended up making it to the gate only a few minutes before it closed due to my waiting for an agent at check in.

The flight was delayed twice and I could not speak with anyone at the airport about checking in. The phone number to Copa - the customer service agents were polite. They are just limited at helping because they are not at the airport

My flight delayed and i misss the connection they send me to orlando no to tampa i have to pay a uber to my house

It would have been better if they don't separate families in seating. We were seated in the aile row in the middle of a family of four. It would have been better if they they seat the family of four together than separated.

No headphones given for inflight entertainment. I missed my flight from the previous day and the customer service agent tried to extort an additional $100.00 US from me for missing my flight. Really?!

It was good, plane is a bit older so seats are somewhat flat

Well the airline was fine. The only thing is I was charged for a checked in luggage. But when I reserved the ticket it showed a check in bag allowed. Who can I get in contact with for reimbursement.? The airline said I had to speak to whoever I booked ticket with.

Friendly flight team and seamless travel from one stop to next.

Terrible. Out flight was delayed for 21 (twenty one) hours. United is a joke.

I fly UAL 7-8 times per year. This flight was not up to snuff because it boarded very late "due to unexpected delays in restocking the plane" and yet Flight Aware showed the plane had landed some 10 hours earlier--so I think they could have planned accordingly. The FA's were nice but harried. The video system had to be rebooted 3-4 times. The food service was rather abrupt; they forgot my row and when I asked for my meal, they brought it with some impatience. Overall, the flight was fine, but the little details made it feel somewhat mundane and hurried.

I didn’t get on plane. Passport being processed by consulate with visa application. Tried to cancel through underpricer after purchasing cacelling for any reason. No dice, they are thieves.

When I booked it on Kayak it aaid that I wasn't allowed hamd luggage. I called United Airlines and it took them 6 minutes to figure out if I was allowed free hand luggage. Surely something that simple they should be able to tell me instantly.

We were delayed in Toronto on the tarmac for THREE hours with no clear indication as to why except that it was not a safety hazard. Pilot did apologize more than once but even he was unable to explain why exactly we were delayed. I overheard the stewards saying that the captain was very frustrated with the situation as well because he was not able to explain why except it had something to do with water supply or system on the aircraft and now we needed to wait for an engineer to approve the aircraft for flight. It was very frustrating and distressing as a passenger and we should have been given complimentary meals at the very least.

Flight was cramped with every seat taken. The food was fine, nothing crazy to write home about. The plane felt dated and needing some TLC, the button for the window shade didn't work and there were no AC outlets to use. When communicating with staff all except one nice lady never seemed happy to help me almost like I was bothering them when asked for things like a glass of water or a snack. The flight was overall fine. It did what was needed which is get me from point A to point B. But it certainly was not special. I don't expect much in economy but I believe economy on a host of other airlines is more memorable and better experience.

The flight was heavily booked so boarding was a lengthy process. The FA’s were rather abrupt during this process but became more gracious as the flight went on. Breakfast (puffed pastry and chewy sausage) was pretty horrible but there was fruit and yogurt which they didn’t mess up. Overall it was fine.

Liked nothing. As per previous segment it was delay delay delay.

Boarding is very confusing. They have Line 1 and Line 2 and many many Boarding groups. Everyone lines up under those two lines long before they call zones. If you have a higher zone 2 like I did due to a Premium Plus ticket, it’s very awkward having to ask each person which zone they have. Extremely chaotic process. On board the flight attendants had no charisma whatsoever, even to us paying extra for an upgraded cabin. I asked for a chamomile tea after dinner (as no coffee or tea was even offered) and the FÃ said they didn’t have even though listed on the drink menu. Also, the mid flight service was entirely skipped which was a soup and sandwich combo. Supposedly had a variety of snacks mid flight too but those never materialized either. A few times I walked Back there, not a single flight attendant acknowledged me as they were all deep into their iPhones. I simply Wanted a glass of water since ZERO water runs were made on this 9hr 30 min flight.

I completely missed my flight because the first leg was longer than planned. I had to sleep overnight in the airport because no accommodation was provided and then sent to Trinidad in the morning with an anticipated 7 hour layover before my flight to Georgetown which was now with Caribbean Airlines. I tried twice with customer service to see if they could put me on an earlier flight which had seats available but was told it wasn’t possible.

Seats are very tight even in Plus, no complimentary snacks or beverage

The chicken that was served in business class was cold!

Flight to Bogotá delayed by 3 h Missed connection from Bogotá to Guayaquil. Avianca unable to bring us to Baltra on time Overall delay 36h. We missed boat departure from galagos. Overall 10 day trip needed to be cancelled. Avianca was completely un-professional.

Late departure. When the flight arrived in Medellin the plane sat at the gate for 20 minutes waiting for a bus for us to get off the plane.

I receive a service for what I pay, so it is fair.

i think the flight was late because they were so strict about measuring everyone's personal items to try and charge them $119. It was really petty and made us late.

A few years ago long flights 6 hours or so used to have video screens and they offered ear phones. The food cart used to come and drinks. Now absolutely nothing. Avianca is as bad as Spirit Airlines. Avianca will now be my last choice when booking my next flight.

Terrible, We had to stay in Bogota for two days due to weather but the airline did not provide for the same day flight. Only two days later

Excellent flight and one of the smoothest landing I’ve ever experienced

There isn't much space in-between seats and even water needs to be paid for during the flight.

Everything you need to know for your flight from Washington, D.C. to Sao Paulo

Cabin class types available on flights from Washington, D.C. to Sao Paulo

Cabin classes available on flights from Washington, D.C. to Sao Paulo. Prices are the lowest found on KAYAK over the last 7 days. Price and availability is not guaranteed.

Not what you’re looking for? Find thousands of other hotels, flights, car rentals and package deals with KAYAK.