Route guide · 694 miles
Cheap Flights from St. Louis to Washington
STL → IAD · Nonstop 1h 55m · Live round-trip fares
If Washington is next on your list, here's the honest picture on fares from St. Louis. The trip covers about 694 miles and takes roughly 1h 55m in the air. Prices on this route reward planners: booking 2–4 weeks ahead is the sweet spot, and the lowest fares tend to sell out fast.
Live fares for STL → IAD 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
STL → IAD
Book ahead
2–4 weeks
Best window, typically
Nonstop airlines
1
United Airlines
Nonstop flights from St. Louis to Washington
Nonstop service links St. Louis and Washington directly — flights are flown by United Airlines. Expect roughly 1h 55m in the air. If a nonstop is what you want, don't wait too long: booking 2–4 weeks ahead is when these seats are priced most kindly.
Booking insights: St. Louis → Washington
- Distance: 694 miles · nonstop flight time: 1h 55m.
- Cheapest upcoming week in the live data starts around Nov 5, with fares from $68.
- Rule of thumb for this route: the sweet spot is usually 2–4 weeks before departure.
- Tuesday and Wednesday departures usually undercut Friday and Sunday fares on routes like this one.
- Set a free Airfare Deal alert instead of checking daily — the best fares can sell out in hours.
Price trend
Cheapest departure weeks ahead
Departing around Nov 5 is currently the cheapest window — about $195 less than the nearest weeks. Based on recent fares found for this route; prices change quickly.
Cheapest month · St. Louis → Washington
November 2026
Every date's recent round-trip fare, at a glance.
Fares from
$68
Cheapest: Wed, Nov 11 — $68
Get this fare →Recent fares found for specific dates in November 2026. Blank days had no recent fare in our data — ask our team and we'll check them for you.
Free fare alerts
Watch St. Louis (STL) → Washington (IAD)
We check this route's fares daily. The moment the price drops, we'll email you — free, unsubscribe anytime.
Talk to a real person
Get St. Louis → Washington flights confirmed by phone
Fares move fast. Call us and we'll confirm the latest price for your dates — or drop your number and we'll call you back. Free, no payment taken on the call.
Request a callback
Flying from St. Louis to Washington: what you need to know
The flight
St. Louis to Washington covers 694 miles, and a nonstop gets it done in about 1h 55m. That's long enough to settle in with a coffee and a downloaded show, short enough that a connection rarely makes sense — a layover usually doubles your travel day to save very little.
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 St. Louis (STL)
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 St. Louis airport guide covers terminals, parking and ground transport so you can plan the trip to the airport, not just the flight.
Arriving in Washington (IAD)
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 Washington airport guide lays out your ground options, from transit and shuttles to rideshares and rental cars. Flying back the other way? Check Washington to St. Louis 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
- Flexible dates? Search a few days either side — one day can change the fare a lot.
- Morning flights are delayed less often than evening ones — earlier departures have the best on-time record.
- Basic economy fares often exclude checked bags and seat selection. Price the whole trip, not the headline fare.
- Get to the airport two hours before departure; security, not the flight, is the part that runs late.
- If you're traveling with only a carry-on, you can skip the bag-drop line entirely with mobile check-in.
St. Louis to Washington flight FAQs
How long is the flight from STL to IAD?
Nonstop flights from St. Louis to Washington take about 1h 55m and cover roughly 694 miles. One-stop itineraries add 2–4 hours depending on the layover city.
Are there nonstop flights from St. Louis to Washington?
Yes — look for United Airlines on this route. Nonstop seats are usually priced best 2–4 weeks before departure.
What is the cheapest month to fly from St. Louis to Washington?
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 STL to IAD?
Last-minute flights from STL to IAD (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 St. Louis to Washington?
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 St. Louis to Washington?
The main carriers on this route are United Airlines. Comparing all of them on the live search below usually surfaces the lowest fare for your dates.
How early should I get to St. Louis 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 St. Louis
How Airfare Deal works — Airfare Deal is a free fare-search and enquiry service. We take no payment online; send an enquiry and our travel team confirms your fare before you pay anything.