Cheap flights from Philadelphia to Seattle from $165

In general, October is the cheapest month to fly from Philadelphia to Seattle. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $317. If you don’t want to visit Seattle in October, then you should wait until January to fly from Philadelphia, when ticket prices are also cheap, with an average price of $318.

On average, the least expensive day to fly to Seattle from Philadelphia is on a Wednesday. momondo users have found tickets for Wednesday departures for as low as $428. However, this price may fluctuate depending on the airline, the season, and holidays. On the other hand, Sunday is the most expensive day to depart from Philadelphia because it is more convenient for both business and leisure travelers. As a result, prices tend to be around $548.

Flying to Seattle from Philadelphia in the evening is the least expensive time of day to depart. momondo users have found prices as low as $457 when looking at flights departing in the evening. Flights to Seattle are more costly in the afternoon, with an average ticket price of $465. Departure times in the afternoon fall within the peak daily travel times, which is why tickets can be more expensive.

Fly from Philadelphia to Seattle/Tacoma Intl for the best Philadelphia - Seattle/Tacoma Intl flight prices

You are more likely to see cheaper flights to Seattle from Philadelphia when booking weeks ahead of your departure date. In general, you can expect to find flights to Seattle for around $389 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Seattle from Philadelphia for as low as $358 on momondo.

There are 4 cabin classes available to choose from on Philadelphia to Seattle flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Southwest, Delta, and United Airlines are the most popular carriers operating from Philadelphia to Seattle/Tacoma Intl

Alaska Airlines, United Airlines and American Airlines are the top three most popular airlines that fly to Seattle from Philadelphia according to our data. Alaska Airlines is the first choice among our users, with 46% of people opting to fly with this airline when traveling to Seattle. Keep in mind that there are 9 different airlines that fly to Seattle on a routine basis, so you have a few additional options to choose from.

Historically, on average around 20% of flights between Philadelphia and Seattle have experienced a delay on any given week. The average delay length over the past 12 months has been 148 minutes.

Generally, flights departing in the morning tend to experience fewer delays. Flights in the early afternoon have, in the past, seen delays more frequently in comparison.

Tuesday is statistically the day of the week which experiences the fewest number of delays on this flight route. Friday has historically seen more delays on average compared to the rest of the week.

According to our data, American Airlines have had the least number of delays on this route over the last 12 months; with about 15% of their flights experiencing any sort of delay.

Detroit (DTW) was the most common stop: 40% of momondo users choosing 1-stop flights on this route connected there.

Flights via Denver (DEN) offer the lowest average round-trip price of $305.

Flights connecting via Detroit (DTW) have the shortest average one-way travel time: 7h 32m.

Detroit (DTW) has the shortest average layover time for this route: 0h 40m.

As of June 2026, 4 flights take off from Philadelphia and land in Seattle each day. The most common flight departure time for this route is 6:00PM, with 76% of daily flights taking off in the evening.

The number of flights available between Philadelphia and Seattle is 31 per week as of June 2026. The most frequent departure day is Wed, with 26% of weekly flights leaving on this day.