Flights St Louis → Philadelphia
As of October 2026, economy flights from St Louis to Philadelphia have a typical range USD 464–792, median USD 626. Full range across all 246 offers: USD 350–1322. We analyzed 246 offers from 9 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: St Louis → Philadelphia
Based on 246 offers · October 2026. Prices and availability change — run a live search to confirm.
Bag & seat fees: St Louis → Philadelphia
Add-on pricing from the cheapest available offer per airline · October 2026 · USD
| Airline | Carry-on | Checked bag | Seat selection |
|---|---|---|---|
| Frontier Airlines | — | — | — |
| Southwest | — | Included | — |
| American Airlines | Included | USD 35 | — |
| United Airlines | Included | USD 35 | — |
| Delta | Included | USD 35 | — |
| Alaska Airlines | 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 Philadelphia cost?
Based on 246 offers · October 2026
St Louis to Philadelphia flights ranged from USD 350 to USD 1322 across 246 offers analyzed in October 2026. The chart below shows how prices distributed across all 246 offers.
These 246 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 617 and USD 646
What hidden fees do St Louis to Philadelphia flights charge?
Ancillary fees — bags, seat selection, and payment surcharges — can add 10–25% to the base fare on St Louis to Philadelphia routes. The breakdown below is based on 246 offers analyzed in October 2026.
| Carrier | Avg fee (USD) | % of base fare |
|---|---|---|
| F9 | 10 | 3% |
| WN | 44 | 6% |
| AA | 45 | 7% |
| UA | 45 | 7% |
| DL | 45 | 7% |
| AS | 45 | 4% |
American Airlines: base ~USD 574 + fees USD 45 = ~USD 619 total. Southwest Airlines: base ~USD 738 + fees USD 44 = ~USD 782 total.
American Airlines's USD 45 ancillary fees narrow the gap with Southwest Airlines's lower-fee model — the USD 164 base difference shrinks to USD 163 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.AA charges 4.5x more in ancillary fees than F9 on this route. Compare total-cost options when booking.
Run your search to see itemized fees for your itineraryWhich airline is cheapest from St Louis to Philadelphia?
9 airlines flew St Louis to Philadelphia 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 (Frontier Airlines), fares ranged USD 350–354 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) |
|---|---|---|---|---|
 Frontier Airlines | 2 | 350–354 | 352 | 10 (3%) |
 Frontier | 3 | — | 355 | n/a |
 AA|F9 | 1 | — | 449 | n/a |
 F9|AA | 1 | — | 529 | n/a |
 American Airlines | 140 | 464–626 | 619 | 45 (7%) |
 United Airlines | 25 | 464–1082 | 646 | 45 (7%) |
 Delta Air Lines | 22 | 646–757 | 646 | 45 (7%) |
 Southwest Airlines | 51 | 464–828 | 782 | 44 (6%) |
 Alaska Airlines | 1 | — | 1090 | 45 (4%) |
Where do the best St Louis → Philadelphia 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 Philadelphia flights
- Full-service carriers on St Louis–Philadelphia cost 1.3x more than budget airlines (USD 663 vs USD 496 median; overall median USD 626).
- AA charges 4.5x more in ancillary fees than F9 — USD 45 vs USD 10 avg per booking.
- The same route priced USD 437 apart depending on where it was booked — the lowest median was USD 355. 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 Philadelphia cost?
- Based on 246 offers analyzed, St Louis to Philadelphia flights range from USD 350 to USD 1322, with a median price of USD 626. Search for your specific dates →
- What hidden fees should I expect on St Louis to Philadelphia flights?
- On average, ancillary fees (bags, seat selection) add USD 45 to the base fare on St Louis to Philadelphia flights. See itemized fees for your itinerary →
- Which airline is cheapest on St Louis to Philadelphia including all fees?
- Frontier Airlines has the lowest median fare on St Louis to Philadelphia at USD 352 (median across 2 offers in our snapshot). Check which airline wins on your dates →
- Which booking site has the cheapest St Louis–Philadelphia 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 355. Run a live search and we'll find the cheapest for you →
- Why do prices vary so much on St Louis to Philadelphia routes?
- St Louis to Philadelphia has 9 airlines competing, creating a price range from USD 350 to USD 1322 across 246 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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