Flights St Louis → Washington DC
As of October 2026, economy flights from St Louis to Washington DC have a typical range USD 390–705, median USD 470. Full range across all 226 offers: USD 355–1126. We found 29% of 226 offers from budget carriers (around USD 470) and 71% from full-service carriers (around USD 470).
Preview snapshot — prices change. Search for live results.
Data collected by LetsFG's multi-source price checks — every airline and the major booking sites checked for this route. How we collect data →
Best offers by airline: St Louis → Washington DC
Based on 226 offers · October 2026. Prices and availability change — run a live search to confirm.
Bag & seat fees: St Louis → Washington DC
Add-on pricing from the cheapest available offer per airline · October 2026 · USD
| Airline | Carry-on | Checked bag | Seat selection |
|---|---|---|---|
| American Airlines | Included | USD 35 | — |
| Frontier Airlines | — | — | — |
| American | — | USD 100 | — |
| United | — | USD 157 | — |
| United | Included | USD 35 | — |
| Southwest Airlines | Included | Included | — |
| Delta | Included | USD 35 | — |
Fees are estimates from the prices we checked and may not reflect your specific itinerary, booking class, or payment method. Run a live search for exact pricing.
How much do flights from St Louis to Washington DC cost?
Based on 226 offers · October 2026
St Louis to Washington DC flights ranged from USD 355 to USD 1126 across 226 offers analyzed in October 2026. Two fare clusters detected: budget fares around 471 and premium fares around 702 The chart below shows how prices distributed across all 226 offers.
These 226 offers (October 2026) span multiple departure dates and booking windows — your travel dates may fall anywhere in this distribution. Only a live search shows where your specific trip lands.
50% of offers priced between USD 470 and USD 475
What hidden fees do St Louis to Washington DC flights charge?
Ancillary fees — bags, seat selection, and payment surcharges — can add 10–25% to the base fare on St Louis to Washington DC routes. The breakdown below is based on 226 offers analyzed in October 2026.
| Carrier | Avg fee (USD) | % of base fare |
|---|---|---|
| AA | 45 | 10% |
| F9 | 122 | 34% |
| American | 131 | 30% |
| United | 132 | 28% |
| UA | 45 | 9% |
| WN | 79 | 12% |
| DL | 45 | 8% |
United: base ~USD 338 + fees USD 132 = ~USD 470 total. American Airlines: base ~USD 425 + fees USD 45 = ~USD 470 total.
United's USD 132 ancillary fees narrow the gap with American Airlines's lower-fee model — the USD 87 base difference shrinks to USD 0 after fees. Always compare total cost, not just the advertised base fare.
Estimates based on median total minus average ancillary fee. Actual base fares vary by itinerary.Fee levels vary significantly across carriers on this route — some carriers charge 50%+ above the base fare in ancillary fees.
Run your search to see itemized fees for your itineraryWhich airline is cheapest from St Louis to Washington DC?
9 airlines flew St Louis to Washington DC in this dataset. The route shows a clear split between low-cost and full-service carriers. Knowing the airline isn't enough — the typical fare range below shows how far prices swing on each one. Median and range include all fees we recorded.
| Airline | Offers | Typical range (USD) | Median (USD) | Fees (USD) |
|---|---|---|---|---|
 Frontier | 1 | — | 355 | n/a |
 Frontier Airlines | 3 | 356–366 | 361 | 122 (34%) |
 American | 7 | 391–493 | 403 | 131 (32%) |
 Southwest | 3 | — | 403 | n/a |
 United Airlines | 43 | 470–482 | 470 | 45 (10%) |
 United | 9 | 458–475 | 470 | 132 (28%) |
 American Airlines | 119 | 390–472 | 470 | 45 (10%) |
 Delta Air Lines | 9 | — | 544 | 45 (8%) |
 Southwest Airlines | 32 | 526–715 | 705 | 79 (11%) |
Where do the best St Louis → Washington DC prices come from?
We checked direct airlines, travel agencies, and meta-search for this route. On this route the lowest median came from travel agency sources, but the cheapest channel shifts by route and date — which is exactly why a live search across all of them wins.
We compare every airline and the major booking sites but never disclose which — that's our edge. Prices are the ones we observed and aren't official data from any platform. Run a live search and we bring you the cheapest, wherever it is.
Key facts: St Louis to Washington DC flights
- Full-service carriers on St Louis–Washington DC cost 1.0x more than budget airlines (USD 471 vs USD 456 median; overall median USD 470).
- United charges 2.9x more in ancillary fees than DL — USD 132 vs USD 45 avg per booking.
- The same route priced USD 378 apart depending on where it was booked — the lowest median was USD 470. We search every airline and the major booking sites at once so you always see that lowest price.
Frequently asked questions
- How much does a flight from St Louis to Washington DC cost?
- Based on 226 offers analyzed, St Louis to Washington DC flights range from USD 355 to USD 1126, with a median price of USD 470. Search for your specific dates →
- What hidden fees should I expect on St Louis to Washington DC flights?
- On average, ancillary fees (bags, seat selection) add USD 57 to the base fare on St Louis to Washington DC flights. See itemized fees for your itinerary →
- Which airline is cheapest on St Louis to Washington DC including all fees?
- Frontier has the lowest median fare on St Louis to Washington DC at USD 355 (median across 1 offers in our snapshot). Check which airline wins on your dates →
- Which booking site has the cheapest St Louis–Washington DC flights?
- It depends on your dates — no single site is always cheapest. We search every airline and the major booking sites at once (travel agencies and meta-search included) and surface whichever is lowest; the best median in this snapshot was USD 470. Run a live search and we'll find the cheapest for you →
- Why do prices vary so much on St Louis to Washington DC routes?
- St Louis to Washington DC has 9 airlines competing, creating a price range from USD 355 to USD 1126 across 226 offers. There are two distinct fare clusters on this route: budget options and premium fares. Find where your trip lands in the distribution →
9 airlines, two price clusters — find which fits your budget
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