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 | $251 (United Airlines) |
One-way from | $146 (Kiwi.com) |
Popular in | June |
Cheapest in | October |
Average price | $507 |
Good round-trip deal | $361 or less |
Good one-way deal | $286 or less |
Fly from
Fly to
Route
Depart
Return
Price
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Sun 1/18
10:10 am-4:01 pm
1 stop8h 51m
Seattle/Tacoma Intl
Tue 1/20
7:00 am-5:34 pm
1 stop7h 34m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Sat 1/17
5:50 am-11:00 am
1 stop8h 10m
Seattle/Tacoma Intl
Tue 1/20
6:45 am-5:05 pm
1 stop7h 20m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Wed 2/18
12:55 pm-7:03 pm
1 stop9h 08m
Seattle/Tacoma Intl
Wed 4/29
11:59 pm-12:17 pm
1 stop9h 18m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Wed 4/29
5:30 pm-9:49 pm
1 stop7h 19m
Seattle/Tacoma Intl
Sun 5/3
4:36 pm-5:35 am
1 stop9h 59m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Thu 2/26
6:20 pm-9:33 pm
Nonstop6h 13m
Seattle/Tacoma Intl
Mon 3/2
9:16 am-5:20 pm
Nonstop5h 04m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Fri 2/6
2:30 pm-11:15 pm
1 stop11h 45m
Seattle/Tacoma Intl
Tue 2/10
11:25 am-11:53 pm
1 stop9h 28m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Mon 4/13
6:47 pm-9:52 pm
Nonstop6h 05m
Seattle/Tacoma Intl
Fri 4/24
9:44 pm-6:02 am
Nonstop5h 18m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Tue 3/10
6:49 pm-12:01 am
1 stop8h 12m
Seattle/Tacoma Intl
Tue 3/17
6:00 am-5:59 pm
1 stop8h 59m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Fri 2/6
5:17 pm-9:49 pm
1 stop7h 32m
Seattle/Tacoma Intl
Mon 2/9
11:10 pm-11:43 am
1 stop9h 33m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Thu 2/5
4:59 pm-11:15 pm
1 stop9h 16m
Seattle/Tacoma Intl
Mon 2/9
1:38 pm-11:53 pm
1 stop7h 15m
| 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*3 stars | |
| Price Accuracy3 stars | Trust Score*2 stars | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy2 stars | 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 $148). 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 19% 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 afternoons flights should be avoided if possible as fares are typically the most expensive at this time.
About 18% of weekly flights between Philadelphia and Seattle have experienced delays in the past year, with the average delay time being 154 minutes.
Historically, flights departing in the morning are less likely to be delayed, whereas flights leaving in the evening tend to experience delays more often.
Wednesday 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, American Airlines have had the lowest number of delays on this route, with just 16% of flights being delayed.
Chicago (ORD) – chosen by Cheapflights users on 33% of 1-stop itineraries from Philadelphia to Seattle on Cheapflights.
Denver (DEN) is the most affordable 1-stop option, with an average round-trip price of $163.
Flights via Chicago (ORD) have the shortest average one-way travel time for 1-stop routes: 8h 04m.
Flights via Chicago (ORD) offer the fastest connection on this route, with an average layover time of 1h 05m.
Crew
Food
Boarding
Entertainment
Overall
Comfort
Reviews
Anonymous,Dec 2025
SJC - SEA
Crew
Food
Boarding
Entertainment
Overall
Comfort
Reviews
Anonymous,Dec 2025
SJC - SEA
Crew
Food
Boarding
Entertainment
Overall
Comfort
Reviews
Anonymous,Dec 2025
SJC - SEA
Crew
Food
Boarding
Entertainment
Overall
Comfort
Reviews
Anonymous,Dec 2025
SJC - SEA
Crew
Food
Boarding
Entertainment
Overall
Comfort
Reviews
Anonymous,Dec 2025
SJC - SEA
Crew
Food
Boarding
Entertainment
Overall
Comfort
Reviews
Anonymous,Dec 2025
SJC - SEA
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$115 | Average$249 | FlexibilityNo cancel fee | On-time65% | |
| Cheapest$134 | Average$295 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$227 | Average$366 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$236 | Average$452 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$238 | Average$365 | FlexibilityNo cancel fee | On-time83% | |
| Cheapest$257 | Average$474 | FlexibilityNo cancel fee | On-time85% | |
| Cheapest$273 | Average$488 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$276 | Average$439 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$277 | Average$435 | FlexibilityNo cancel fee | On-time71% |