Flights Seattle → St Louis
As of September 2026, economy flights from Seattle to St Louis have a typical range USD 509–600, median USD 563. Full range across all 175 offers: USD 426–813. We analyzed 175 offers from 7 airlines in a single price check.
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: Seattle → St Louis
Based on 175 offers · September 2026. Prices and availability change — run a live search to confirm.
Bag & seat fees: Seattle → St Louis
Add-on pricing from the cheapest available offer per airline · September 2026 · USD
| Airline | Carry-on | Checked bag | Seat selection |
|---|---|---|---|
| JetBlue | Included | — | — |
| American Airlines | Included | USD 35 | — |
| Delta | Included | USD 35 | — |
| United | Included | USD 35 | — |
| Southwest Airlines | Included | Included | — |
| Alaska Airlines | Included | USD 104 | — |
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 Seattle to St Louis cost?
Based on 175 offers · September 2026
Seattle to St Louis flights ranged from USD 426 to USD 813 across 175 offers analyzed in September 2026. The chart below shows how prices distributed across all 175 offers.
These 175 offers (September 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 530 and USD 583
What hidden fees do Seattle to St Louis flights charge?
Ancillary fees — bags, seat selection, and payment surcharges — can add 10–25% to the base fare on Seattle to St Louis routes. The breakdown below is based on 175 offers analyzed in September 2026.
| Carrier | Avg fee (USD) | % of base fare |
|---|---|---|
| B6 | 19 | 4% |
| AA | 49 | 9% |
| DL | 45 | 8% |
| UA | 45 | 8% |
| WN | 45 | 8% |
| AS | 114 | 14% |
American Airlines: base ~USD 517 + fees USD 49 = ~USD 566 total. Southwest Airlines: base ~USD 527 + fees USD 45 = ~USD 572 total.
American Airlines's USD 49 ancillary fees narrow the gap with Southwest Airlines's lower-fee model — the USD 10 base difference shrinks to USD 6 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 Seattle to St Louis?
7 airlines flew Seattle to St Louis in this dataset. 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.
Even on the cheapest airline (B6), fares ranged USD 492–548 in this snapshot. Your exact price depends on your dates and how far ahead you book — run a live search to see your number →
| Airline | Offers | Typical range (USD) | Median (USD) | Fees (USD) |
|---|---|---|---|---|
 B6 | 39 | 492–548 | 542 | 19 (4%) |
 American Airlines | 53 | 517–593 | 566 | 49 (9%) |
 Southwest Airlines | 48 | 523–652 | 572 | 45 (8%) |
 Delta Air Lines | 24 | 496–586 | 576 | 45 (8%) |
 United Airlines | 9 | 527–592 | 585 | 45 (8%) |
 AS|B6|WN | 1 | — | 747 | n/a |
 Alaska Airlines | 1 | — | 788 | 114 (14%) |
Where do the best Seattle → St Louis prices come from?
We checked direct airlines, travel agencies, and meta-search for this route. On this route the lowest median came from meta-search 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: Seattle to St Louis flights
- Full-service carriers on Seattle–St Louis cost 1.2x more than budget airlines (USD 653 vs USD 557 median; overall median USD 563).
- AS charges 6.0x more in ancillary fees than B6 — USD 114 vs USD 19 avg per booking.
- The same route priced USD 218 apart depending on where it was booked — the lowest median was USD 529. 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 Seattle to St Louis cost?
- Based on 175 offers analyzed, Seattle to St Louis flights range from USD 426 to USD 813, with a median price of USD 563. Search for your specific dates →
- What hidden fees should I expect on Seattle to St Louis flights?
- On average, ancillary fees (bags, seat selection) add USD 41 to the base fare on Seattle to St Louis flights. See itemized fees for your itinerary →
- Which airline is cheapest on Seattle to St Louis including all fees?
- B6 has the lowest median fare on Seattle to St Louis at USD 542 (median across 39 offers in our snapshot). Check which airline wins on your dates →
- Which booking site has the cheapest Seattle–St Louis 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 529. Run a live search and we'll find the cheapest for you →
- Why do prices vary so much on Seattle to St Louis routes?
- Seattle to St Louis has 7 airlines competing, creating a price range from USD 426 to USD 813 across 175 offers. Prices on this route change with booking timing, advance purchase, and ancillary add-ons. Find where your trip lands in the distribution →
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