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 | $237 (Alaska Airlines) |
One-way from | $141 (Kiwi.com) |
Popular in | June |
Cheapest in | October |
Average price | $342 |
Good round-trip deal | $357 or less |
Good one-way deal | $245 or less |
Fly from
Fly to
Route
Depart
Return
Price
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Thu 5/7
6:58 pm-10:02 pm
Nonstop6h 04m
Seattle/Tacoma Intl
Tue 5/19
9:27 pm-5:40 am
Nonstop5h 13m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Sun 5/10
7:05 am-10:04 am
Nonstop5h 59m
Seattle/Tacoma Intl
Wed 5/20
9:50 pm-6:05 am
Nonstop5h 15m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Thu 4/16
7:25 am-10:30 am
Nonstop6h 05m
Seattle/Tacoma Intl
Tue 4/21
9:55 pm-6:05 am
Nonstop5h 10m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Sat 5/9
7:22 am-10:20 am
Nonstop5h 58m
Seattle/Tacoma Intl
Sat 5/16
9:27 pm-5:40 am
Nonstop5h 13m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Fri 3/13
6:22 pm-9:35 pm
Nonstop6h 13m
Seattle/Tacoma Intl
Sat 3/21
9:55 pm-6:05 am
Nonstop5h 10m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Fri 4/10
7:25 am-10:30 am
Nonstop6h 05m
Seattle/Tacoma Intl
Sat 4/18
9:55 pm-6:05 am
Nonstop5h 10m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Fri 5/8
6:58 pm-10:02 pm
Nonstop6h 04m
Seattle/Tacoma Intl
Sat 5/16
9:27 pm-5:40 am
Nonstop5h 13m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Fri 4/24
6:45 pm-11:59 pm
1 stop8h 14m
Seattle/Tacoma Intl
Fri 5/1
11:14 pm-11:34 am
1 stop9h 20m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Fri 2/6
6:37 pm-12:09 am
1 stop8h 32m
Seattle/Tacoma Intl
Mon 2/9
1:38 pm-11:53 pm
1 stop7h 15m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Fri 3/6
6:50 pm-12:09 am
1 stop8h 19m
Seattle/Tacoma Intl
Thu 3/26
11:59 pm-10:45 am
1 stop7h 46m
| 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 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 July is currently the most expensive (average of $223). 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.
When flying from Philadelphia to Seattle, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.
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.
Boarding
Crew
Entertainment
Comfort
Overall
Food
Reviews
Anonymous,Dec 2025
SJC - SEA
Boarding
Crew
Entertainment
Comfort
Overall
Food
Reviews
Anonymous,Dec 2025
SJC - SEA
Boarding
Crew
Entertainment
Comfort
Overall
Food
Reviews
Anonymous,Dec 2025
SJC - SEA
Boarding
Crew
Entertainment
Comfort
Overall
Food
Reviews
Anonymous,Dec 2025
SJC - SEA
Boarding
Crew
Entertainment
Comfort
Overall
Food
Reviews
Anonymous,Dec 2025
SJC - SEA
Boarding
Crew
Entertainment
Comfort
Overall
Food
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$223 | Average$362 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$236 | Average$451 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$238 | Average$365 | FlexibilityNo cancel fee | On-time83% | |
| Cheapest$257 | Average$474 | FlexibilityNo cancel fee | On-time85% | |
| Cheapest$263 | Average$484 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$276 | Average$449 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$277 | Average$435 | FlexibilityNo cancel fee | On-time71% |