Route guide · 694 miles
Cheap Flights from Washington to St. Louis
IAD → STL · Nonstop 1h 55m · Live round-trip fares
Plenty of travelers price out Washington to St. Louis every day — here's how to beat the average fare. Nonstops run about 1h 55m, and the calendar matters more than the airline. Aim to book 2–4 weeks ahead, stay flexible on the day of the week, and set a free alert so a price drop never slips past you.
Live fares for IAD → STL are updating. Use the search below for real-time prices.
Search live pricesCheapest recent fare
See live fares
Updated daily
Flight time
1h 55m
Nonstop, typical
Distance
694 mi
IAD → STL
Book ahead
2–4 weeks
Best window, typically
Nonstop airlines
1
United Airlines
Nonstop flights from Washington to St. Louis
Nonstop flights from Washington to St. Louis are flown by United Airlines. The 694-mile trip takes about 1h 55m gate to gate, and nonstops are usually cheapest when booked 2–4 weeks ahead.
Booking insights: Washington → St. Louis
- Distance: 694 miles · nonstop flight time: 1h 55m.
- Cheapest upcoming week in the live data starts around Oct 22, with fares from $184.
- Fares tend to bottom out when you book about 2–4 weeks ahead — earlier than that rarely helps, later usually hurts.
- Midweek departures (Tue–Thu) are consistently cheaper than weekend flights.
- A free fare alert beats daily checking: we watch this route and ping you when prices drop.
Price trend
Cheapest departure weeks ahead
Departing around Oct 22 is currently the cheapest window — about $12 less than the nearest weeks. Based on recent fares found for this route; prices change quickly.
Cheapest month · Washington → St. Louis
October 2026
Every date's recent round-trip fare, at a glance.
Fares from
$184
Cheapest: Fri, Oct 23 — $184 · Priciest: Oct 21 — $196
Get this fare →Recent fares found for specific dates in October 2026. Blank days had no recent fare in our data — ask our team and we'll check them for you.
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Flying from Washington to St. Louis: what you need to know
The flight
The nonstop from IAD to STL runs about 1h 55m over 694 miles. It's a comfortable mid-range flight: long enough that seat choice matters a little, short enough that paying up for extras rarely does.
Airlines on this route
United Airlines flies this route nonstop. That matters more than it sounds: the cheapest fare on one carrier is rarely the same product as the cheapest on another. Checked-bag fees, free seat selection and change rules all differ, so compare the full trip cost before you pick a winner. See our airline guides for exactly what each carrier charges — then send an enquiry and we'll confirm the all-in price for your dates.
Leaving from Washington (IAD)
Plan to be at the airport two hours before a domestic departure — ninety minutes can work at smaller airports outside peak times, but security lines are the one variable you can't control. If you're checking a bag, add time rather than cutting it close. Our Washington airport guide covers terminals, parking and ground transport so you can plan the trip to the airport, not just the flight.
Arriving in St. Louis (STL)
Before you land, know how you're getting from the airport to where you're staying — it's the part of the trip people forget to plan. The St. Louis airport guide lays out your ground options, from transit and shuttles to rideshares and rental cars. Flying back the other way? Check St. Louis to Washington fares — prices on the return direction often move on a different rhythm.
When to book
For a trip of 694 miles, booking 2–4 weeks ahead typically lands you in the sweet spot. Leave it to the final two weeks and prices usually climb as the cheapest seats sell out. If your dates are flexible, midweek departures are where the lower fares hide on most domestic routes.
Good to know before you go
- Download the airline's app before you fly; gate changes and delays show up there first.
- Nonstop time on this route is about 1h 55m — a one-stop itinerary needs to be a lot cheaper to be worth the extra hours.
- Tuesday and Wednesday departures are typically the cheapest days on domestic routes.
- Screenshot your fare before you enquire — prices move, and a saved fare helps our team match or beat it.
- Flexible dates? Search a few days either side — one day can change the fare a lot.
Washington to St. Louis flight FAQs
How long is the flight from IAD to STL?
Plan on about 1h 55m in the air for a nonstop from Washington to St. Louis — the route runs roughly 694 miles. Connecting flights typically add 2–4 hours.
Are there nonstop flights from Washington to St. Louis?
United Airlines typically operate nonstop flights from IAD to STL. Nonstops are usually cheapest when booked 2–4 weeks ahead of departure.
What is the cheapest month to fly from Washington to St. Louis?
There's no single magic month, but prices on this route generally soften in the shoulder season, when demand dips after the holidays and again in early fall. A free fare alert is the easiest way to catch those windows.
How much are last minute flights from IAD to STL?
Last-minute flights from IAD to STL (booked within 7 days of departure) typically cost noticeably more than fares booked 2–4 weeks out. Booking early is the smarter move.
What is a good round-trip deal from Washington to St. Louis?
A good deal is anything at or below the recent fares shown above. Set a free Airfare Deal alert and we'll ping you the moment fares drop.
Which airlines fly from Washington to St. Louis?
You'll mainly see United Airlines on Washington to St. Louis. Checking each against the live fares below is the surest way to find the lowest price for your dates.
How early should I get to Washington airport for this flight?
Plan on two hours before departure for a domestic flight — ninety minutes can work at smaller airports outside peak times. If you're checking a bag, earlier is better; the bag-drop line, not the flight, is what runs late.
Do the cheapest fares on this route include a checked bag?
Usually not. Basic economy fares on most airlines include a carry-on but charge extra for checked bags, and seat selection can cost more too. Add up the real total before comparing — a slightly higher regular fare sometimes works out cheaper. Our team confirms the full breakdown with you before you pay.
More cheap flights from Washington
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