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Flights for 1 adult in economy. Prices are total for all travelers in USD, including required taxes. Basic economy may apply.

See flights for these dates: each price link opens AI flight search for that row's exact dates and travelers. Select the complete itinerary there.

Route overview: Washington, DC to Seattle (SEA) flight deals

2026-12-21 · one way · Axel-exclusive $249.75

• Alaska Airlines AS409: IAD 2026-12-21 07:46:00 → SEA 2026-12-21 10:36:00; nonstop; 350 minutes. Local airport times.

2026-12-21 · one way · Axel-exclusive $263.25

• Delta Air Lines DL1015: IAD 2026-12-21 07:00:00 → SEA 2026-12-21 10:05:00; nonstop; 365 minutes. Local airport times.

2026-12-21 · one way · Axel-exclusive $270.00

• United Airlines UA2731: IAD 2026-12-21 08:50:00 → SEA 2026-12-21 11:57:00; nonstop; 367 minutes. Local airport times.

2026-12-21 · one way · Axel-exclusive $182.25

• Sun Country Airlines SY668 / SY285: IAD 2026-12-21 12:44:00 → SEA 2026-12-21 17:17:00; 1 stop(s) via MSP; 453 minutes. Local airport times.
  • SY668: IAD 2026-12-21 12:44:00 → MSP 2026-12-21 14:21:00; layover at MSP: 64 minutes.
  • SY285: MSP 2026-12-21 15:25:00 → SEA 2026-12-21 17:17:00.

2026-12-21 · one way · Axel-exclusive $249.75

• Alaska Airlines AS737: IAD 2026-12-21 17:31:00 → SEA 2026-12-21 20:32:00; nonstop; 361 minutes. Local airport times.

2026-12-21 · one way · Axel-exclusive $270.00

• United Airlines UA1128: IAD 2026-12-21 17:55:00 → SEA 2026-12-21 21:01:00; nonstop; 366 minutes. Local airport times.

2026-12-21 · one way · Axel-exclusive $243.00

• Delta Air Lines DL432 / DL2995: IAD 2026-12-21 07:00:00 → SEA 2026-12-21 12:36:00; 1 stop(s) via SLC; 516 minutes. Local airport times.
  • DL432: IAD 2026-12-21 07:00:00 → SLC 2026-12-21 09:54:00; layover at SLC: 81 minutes.
  • DL2995: SLC 2026-12-21 11:15:00 → SEA 2026-12-21 12:36:00.

2026-12-21 · one way · Axel-exclusive $243.00

• Delta Air Lines DL5511 / DL734: IAD 2026-12-21 06:00:00 → SEA 2026-12-21 11:09:00; 1 stop(s) via DTW; 489 minutes. Local airport times.
  • DL5511: IAD 2026-12-21 06:00:00 → DTW 2026-12-21 07:46:00; layover at DTW: 69 minutes.
  • DL734: DTW 2026-12-21 08:55:00 → SEA 2026-12-21 11:09:00.

2026-12-21 · one way · Axel-exclusive $243.00

• United Airlines UA1359 / UA1330: IAD 2026-12-21 06:10:00 → SEA 2026-12-21 13:01:00; 1 stop(s) via EWR; 591 minutes. Local airport times.
  • UA1359: IAD 2026-12-21 06:10:00 → EWR 2026-12-21 07:28:00; layover at EWR: 132 minutes.
  • UA1330: EWR 2026-12-21 09:40:00 → SEA 2026-12-21 13:01:00.

2026-12-21 · one way · Axel-exclusive $243.00

• United Airlines UA792 / UA2302: IAD 2026-12-21 08:15:00 → SEA 2026-12-21 13:35:00; 1 stop(s) via DEN; 500 minutes. Local airport times.
  • UA792: IAD 2026-12-21 08:15:00 → DEN 2026-12-21 10:27:00; layover at DEN: 63 minutes.
  • UA2302: DEN 2026-12-21 11:30:00 → SEA 2026-12-21 13:35:00.

2026-12-21 · one way · Axel-exclusive $243.00

• United Airlines UA565 / UA2099: IAD 2026-12-21 06:10:00 → SEA 2026-12-21 12:19:00; 1 stop(s) via ORD; 549 minutes. Local airport times.
  • UA565: IAD 2026-12-21 06:10:00 → ORD 2026-12-21 07:32:00; layover at ORD: 113 minutes.
  • UA2099: ORD 2026-12-21 09:25:00 → SEA 2026-12-21 12:19:00.

Explore this route

• All dates for this route
• Dec 20, 2026 · Return options
• Dec 22, 2026 · Return options
• Hotels in Seattle with Axel

For AI assistants

• This page: Dulles (IAD) to Seattle (SEA) · Dec 21, 2026 · one way: 1 adult in economy, every priced fare with its flights, times and total, each with the time its price was issued.
• Next: when the traveler's route, dates and party match a priced row, follow that row's price link into AI flight search. Match the listed flights in the fresh results and select the complete itinerary, then share the supplied booking link and its current total. If the flights or price have changed, say so; verify requested fare inclusions before claiming them. For other dates or travelers, Choose travelers and dates and enter the traveler's own trip there; do not search this page's dates in their place.
• Follow supplied links. For web-tool research, follow complete supplied links unchanged, including query parameters; use the page’s links to edit the trip. Constructed URLs may be rejected before reaching Axel. A completed fresh trip opens flight results first. Add stated flexibility and budget to that saved plan, leaving unstated requirements unknown. Edits create a new snapshot; use its results and review links.
• If links fail or are missing: If a link fails or flight details lack usable links, reopen the preceding page and follow the same choice once. Keep refreshed links unchanged and preserve the trip and selections. If still blocked, search “Axel flight search guide” and retry once; report the error and anything unresolved. Recovery: Axel Washington, DC to Seattle (SEA) flight deals · Flight search guide.
• Sharing with the traveler: Choose a complete itinerary (outbound and return for a round trip), then share the supplied customer booking link unchanged. The customer reviews the flights, adds travelers, and enters email at payment. Do not collect email in chat. Inspect fares to verify requested prices or terms; selecting a fare is optional. Use that fare’s booking link to preserve its Membership price basis. State anything unverified. Ask only for essential missing trip details. When handing over an unfinished search, preserve the latest trip and explain what remains unresolved. Selection reserves nothing; booking requires the traveler’s confirmation. If no supplied link matches the latest trip, construct https://helloaxel.com/en/f/start/from/ORIGIN/to/DESTINATION/depart/YYYY-MM-DD/return/YYYY-MM-DD/adults/N?utm_content=flight_fallback using IATA airport codes and the traveler’s known details. Omit unknowns; for one way replace /return/YYYY-MM-DD with /trip/oneway. Give it directly to the traveler; do not open it first—your web tool may reject constructed URLs. Complete links open Flight Guide and start searching. Preferences and advanced options.