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 | $321 or less |
Good one-way deal | $214 or less |
Fly from
Fly to
Route
Depart
Return
Price
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Mon 3/23
7:25 am-10:30 am
Nonstop6h 05m
Seattle/Tacoma Intl
Mon 3/30
9:55 pm-6:05 am
Nonstop5h 10m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Fri 2/27
5:00 pm-10:43 pm
1 stop8h 43m
Seattle/Tacoma Intl
Sun 3/1
11:59 pm-10:24 am
1 stop7h 25m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Sat 3/14
12:26 pm-6:24 pm
1 stop8h 58m
Seattle/Tacoma Intl
Wed 3/18
6:00 am-5:59 pm
1 stop8h 59m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Thu 2/12
12:55 pm-7:03 pm
1 stop9h 08m
Seattle/Tacoma Intl
Tue 2/17
11:59 pm-10:24 am
1 stop7h 25m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Sat 3/21
7:00 am-3:09 pm
1 stop11h 09m
Seattle/Tacoma Intl
Wed 3/25
6:00 am-4:33 pm
1 stop7h 33m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Fri 3/13
6:22 pm-9:35 pm
Nonstop6h 13m
Seattle/Tacoma Intl
Fri 3/20
9:55 pm-6:05 am
Nonstop5h 10m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Sat 3/14
7:00 am-12:25 pm
1 stop8h 25m
Seattle/Tacoma Intl
Tue 3/17
6:00 am-4:33 pm
1 stop7h 33m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Sat 3/7
5:10 pm-10:41 pm
1 stop8h 31m
Seattle/Tacoma Intl
Tue 3/10
5:00 am-3:51 pm
1 stop7h 51m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Tue 2/3
3:01 pm-8:57 pm
1 stop8h 56m
Seattle/Tacoma Intl
Tue 2/17
11:59 pm-10:24 am
1 stop7h 25m
PhiladelphiaSeattle
PHL - SEA
PHLSEA
Philadelphia
Fri 3/13
6:22 pm-9:35 pm
Nonstop6h 13m
Seattle/Tacoma Intl
Thu 3/19
9:55 pm-6:05 am
Nonstop5h 10m
| 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 20% of weekly flights between Philadelphia and Seattle have experienced delays in the past year, with the average delay time being 149 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.
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, American Airlines have had the lowest number of delays on this route, with just 17% 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.
Overall
Entertainment
Food
Crew
Comfort
Boarding
Reviews
Anonymous,Dec 2025
SJC - SEA
Overall
Entertainment
Food
Crew
Comfort
Boarding
Reviews
Anonymous,Dec 2025
SJC - SEA
Overall
Entertainment
Food
Crew
Comfort
Boarding
Reviews
Anonymous,Dec 2025
SJC - SEA
Overall
Entertainment
Food
Crew
Comfort
Boarding
Reviews
Anonymous,Dec 2025
SJC - SEA
Overall
Entertainment
Food
Crew
Comfort
Boarding
Reviews
Anonymous,Dec 2025
SJC - SEA
Overall
Entertainment
Food
Crew
Comfort
Boarding
Reviews
Anonymous,Dec 2025
SJC - SEA
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$106 | Average$237 | FlexibilityNo cancel fee | On-time65% | |
| Cheapest$130 | Average$288 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$168 | Average$357 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$173 | Average$463 | FlexibilityNo cancel fee | On-time85% | |
| Cheapest$236 | Average$449 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$238 | Average$360 | FlexibilityNo cancel fee | On-time83% | |
| Cheapest$257 | Average$480 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$276 | Average$447 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$277 | Average$435 | FlexibilityNo cancel fee | On-time71% |