Seattle is my home airport and I have a lot of experience with international arrivals there. It takes about 7-10 minutes to walk from the gate to the baggage hall/ customs area. (Speed hint, if you need to use the restroom don’t stand in line at the first one you see. The one down in baggage claim never has a line). You must collect your luggage before going through passport control. Here is where you really roll the dice on timing. The number of flights arriving at the same time, where your luggage was on the plane, etc all play into an unpredictable timing. I’ve had my luggage in a range from 15 minutes up to an hour. Carryon will allow you to skip this very time consuming step.
Next is passport control. I have Global Entry. I do a face scan and am through in about 2 minutes. Mobile passport is your next best option if you don’t have Global entry. This line is on the far left of the building, just beside Global Entry. My friends tell me this is usually 5-10 minutes.
You now follow the hallway to the right after passport control for connecting flights. It can take up to 15 minutes to get to the other side of the airport.
There is a chance you can make this connection with carryon, but don’t even think of connecting if you have checked luggage.