For quick check-in, verify your airline’s terminal before arriving. Terminals are spread out, and only some are linked by indoor walkways.

Most accurate provider | CheapOair 3 stars |
|---|---|
Most trusted provider | CheapOair 3 stars |
Round-trip from | $257 (Kiwi.com) |
One-way from | $143 (Kiwi.com) |
Popular in | June |
Cheapest in | October |
Average price | $427 |
Good round-trip deal | $365 or less |
Good one-way deal | $216 or less |
Fly from
Fly to
Route
Depart
Return
Price
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Fri 1/23
6:37 pm-12:09 am
1 stop8h 32m
Seattle/Tacoma Intl
Thu 1/29
1:38 pm-11:14 pm
1 stop6h 36m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Sat 12/6
12:37 pm-8:50 pm
1 stop11h 13m
Seattle/Tacoma Intl
Sun 12/7
2:03 pm-12:51 am
1 stop7h 48m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Fri 1/23
6:00 am-10:47 am
1 stop7h 47m
Seattle/Tacoma Intl
Mon 1/26
10:59 pm-9:50 am
1 stop7h 51m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Mon 12/8
6:07 pm-11:58 pm
1 stop8h 51m
Seattle/Tacoma Intl
Mon 12/15
11:15 pm-11:37 am
1 stop9h 22m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Mon 1/12
10:30 am-6:26 pm
2 stops10h 56m
Seattle/Tacoma Intl
Thu 1/22
10:58 am-9:51 pm
1 stop7h 53m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Wed 12/3
5:07 pm-10:28 pm
1 stop8h 21m
Seattle/Tacoma Intl
Wed 12/10
7:34 pm-9:35 am
2 stops11h 01m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Wed 1/28
12:15 pm-10:35 pm
2 stops13h 20m
Seattle/Tacoma Intl
Tue 2/3
6:25 am-10:00 pm
2 stops12h 35m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Mon 1/12
5:40 am-4:00 pm
2 stops13h 20m
Seattle/Tacoma Intl
Thu 1/22
6:05 am-8:20 pm
2 stops11h 15m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Fri 12/12
3:20 pm-8:00 pm
1 stop7h 40m
Seattle/Tacoma Intl
Sun 12/14
5:50 am-7:20 pm
2 stops10h 30m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Tue 12/23
12:13 pm-10:24 am
1 stop25h 11m
Seattle/Tacoma Intl
Tue 12/30
6:34 pm-10:18 am
1 stop12h 44m
| Provider | Price Accuracy | Trust Score* |
|---|---|---|
| Price Accuracy2 stars | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*1 star | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy- | Trust Score*1 star | |
| Price Accuracy- | Trust Score*1 star | |
| Price Accuracy3 stars | Trust Score*2 stars | |
| Price Accuracy2 stars | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy1 star | Trust Score*3 stars |
The best time to book flights from Philadelphia to Seattle is 71 days before your desired departure date. The cost of your flight will likely increase significantly if you book two weeks in advance of your flight.
Currently, October is the cheapest month in which you can book a flight from Philadelphia to Seattle (average of $140). Flying from Philadelphia to Seattle in April is currently the most expensive (average of $237). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.
One of the essential ways to save on airfare from Philadelphia to Seattle is to remain as flexible as possible. Flights that are in the morning tend to be the most expensive. A flight at noon could potentially save you up to 20% on airfare.
Travelers seeking maximum savings on their Philadelphia to Seattle flight should consider departing on Tuesday at noon when fares are most often at their lowest. Sunday mornings flights should be avoided if possible as fares are typically the most expensive at this time.
About 21% of weekly flights between Philadelphia and Seattle have experienced delays in the past year, with the average delay time being 158 minutes.
Historically, flights departing in the early afternoon are less likely to be delayed, whereas flights leaving in the evening tend to experience delays more often.
Tuesday tends to have the lowest number of delays on this route, whereas Friday has historically faced a higher average of delays compared to other days of the week.
Over the last year, Delta have had the lowest number of delays on this route, with no flights being classified as delayed.
Comfort
Entertainment
Boarding
Overall
Crew
Food
Reviews
Anonymous,Aug 2025
MFR - SEA
Comfort
Entertainment
Boarding
Overall
Crew
Food
Reviews
Anonymous,Aug 2025
MFR - SEA
Comfort
Entertainment
Boarding
Overall
Crew
Food
Reviews
Anonymous,Aug 2025
MFR - SEA
Comfort
Entertainment
Boarding
Overall
Crew
Food
Reviews
Anonymous,Aug 2025
MFR - SEA
Comfort
Entertainment
Boarding
Overall
Crew
Food
Reviews
Anonymous,Aug 2025
MFR - SEA
Comfort
Entertainment
Boarding
Overall
Crew
Food
Reviews
Anonymous,Aug 2025
MFR - SEA
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$127 | Average$252 | FlexibilityNo cancel fee | On-time65% | |
| Cheapest$130 | Average$295 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$233 | Average$377 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$238 | Average$361 | FlexibilityNo cancel fee | On-time83% | |
| Cheapest$257 | Average$474 | FlexibilityNo cancel fee | On-time85% | |
| Cheapest$277 | Average$490 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$277 | Average$443 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$286 | Average$449 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$294 | Average$456 | FlexibilityNo cancel fee | On-time63% |