It is one of the easiest interstate hops in the Pacific Northwest, a straight shot down I-5. But the cost to drive from Seattle to Portland surprises people, because Washington and Oregon both carry higher-than-average gas prices.
The drive is only about 175 miles, so the fuel bill is modest in dollars. Here is the exact math across vehicles, a small quirk about pumping gas in Oregon, and whether the train beats the car on this corridor.
What it costs to drive from Seattle to Portland
Here is the same trip at three common fuel-economy levels, based on about 175 miles and roughly $4.35 a gallon. Find where your car lands, and remember round-trip simply doubles it.
| Your car’s MPG | One-way | Round-trip |
|---|---|---|
| 20 MPG | $38.06 | $76.13 |
| 30 MPG | $25.37 | $50.75 |
| 40 MPG | $19.03 | $38.06 |
Those figures assume a fairly efficient car. Drive something thirstier, or hit mountains, heat, or heavy traffic, and your real number climbs. That is exactly why it helps to price the trip by your own vehicle rather than a generic average. And remember, the gas figure is per car, not per person: split it among three or four passengers and the Seattle to Portland drive becomes one of the cheapest ways to travel, often beating a single plane ticket outright.
How your vehicle changes the cost to drive from Seattle to Portland
The number that matters most is not the pump price. It is your car. On a 175-mile drive at about $4.35 a gallon, the gap between a thrifty hybrid and a thirsty pickup is dramatic. Here is the same trip across five common vehicle types so you can see where yours lands.
| Vehicle type | One-way gas | Round-trip gas |
|---|---|---|
| Hybrid (~48 MPG) | $15.86 | $31.72 |
| Compact car (~38 MPG) | $20.03 | $40.07 |
| Midsize sedan (~30 MPG) | $25.37 | $50.75 |
| SUV / crossover (~24 MPG) | $31.72 | $63.44 |
| Pickup / large SUV (~17 MPG) | $44.78 | $89.56 |
See the spread? Swapping a 17-MPG truck for a 30-MPG sedan can cut the fuel bill for this route roughly in half. If you own more than one vehicle, this table alone can tell you which one to take, which is a small decision that quietly saves real money over a year of trips. Real-world mileage tends to run 10 to 15% below the window sticker, thanks to how you drive, tire pressure, cargo weight, and even the weather, so measure yours with the MPG calculator before you trust any estimate. Then run your own figure through the gas cost calculator for a number matched to your exact car, and use the fuel consumption calculator to see the gallons you will actually burn.
The real cost is more than gas
Fuel is the headline, but it is rarely the whole bill. I-5 between the two cities is toll-free, so gas is essentially your only road cost. Then there is the stuff most people forget: coffee and snacks at every stop, a meal or two on a longer haul, and the slow, invisible cost of wear on your tires, brakes, and engine.
That wear is real money. When you price a trip by cost per mile instead of gas alone, you capture maintenance and depreciation too, which is how rideshare and delivery drivers think about every mile. A good habit is to pad your fuel estimate by 10 to 15% to cover the odd detour, an unexpected price jump, or a heavier load than planned, so you are never caught short at the pump. For a clean way to line up fuel, tolls, food, and lodging for this trip, drop them into the gas budget worksheet and you will get a number you can actually plan around.
What moves the price on the Seattle to Portland drive
West Coast gas prices. You start in Washington and finish in Oregon, both of which run above the national average. See how they compare with the rest of the country on the most expensive states page.
Pumping in Oregon. Oregon eased its long-standing self-serve rules in recent years, so you may still find full-serve stations. It rarely changes the price much, but it can slow your stop.
Traffic and MPG. The I-5 corridor around Tacoma, Olympia, and Portland gets congested at peak hours. A clean run keeps mileage high; rush hour drags it down.
Where to fill up cheapest on the Seattle to Portland drive
Both states run high, so the savings here are about timing and location, not crossing a cheap border. Fill up away from the downtown cores and the busy freeway exits, where prices climb. Washington and Oregon often trade places for the cheaper average week to week, so a quick check of both before you go tells you which end to fill at. Because the drive is short, one smart fill-up usually covers the round trip.
Before you leave, glance at the live gas price tracker so you know what a good price looks like, and compare state-by-state averages on the gas prices by state page. On the road, a gas price app will point you to the cheapest pump near your exit instead of the first flashy sign off the ramp, which is often the priciest.
Should you drive, fly, or take the bus?
Flying Seattle to Portland makes little sense given the short distance and airport overhead. The real rival is Amtrak Cascades, a scenic, comfortable train that can beat driving for a solo traveler once you count parking. Driving wins for groups or when you need the car in Portland.
The rule of thumb: driving usually wins when you are splitting fuel between passengers or need your car at the destination, while flying or the bus can win for a solo traveler on a longer route. Run the trade-off with the logic in our fly vs drive cost calculator guide before you book anything.
Doing this trip in an electric car?
If you are behind the wheel of an EV, the math flips in your favor. Covering 175 miles takes roughly 53 kWh for a typical electric car. Charge at home at normal residential rates and that works out to about $7.35 to $9.45 one-way, well under the $25.37 a 30-MPG gas car would burn. Lean on public DC fast chargers and it climbs to around $23.63, since fast charging costs more per kWh. The Pacific Northwest has strong fast-charging coverage and cheap, often hydro-powered electricity, so an EV is especially economical on this route.
Charging prices swing a lot by state and network, so check EV charging prices by state and put the full comparison side by side with EV vs gas by state before you assume the plug always wins.
The best time to make the Seattle to Portland drive
Summer is peak travel and peak prices in the Northwest, while winter brings rain and occasional mountain-pass weather if you detour. A weekday off-season drive is smoothest and cheapest.
Prices also drift over the week. Gas is often cheapest early in the week and creeps up before the weekend, which we break down in our best day to buy gas guide. Time your fill-up accordingly and you shave a little off every gallon.
How to spend less on the Seattle to Portland drive
- Compare Washington and Oregon averages on the gas price tracker before you fill up.
- Use a gas price app to spot the cheapest station near your exit.
- Commuting or shuttling this route? Try the cost per mile calculator.
- Consider the scenic train with our fly vs drive comparison logic.
- Driving an EV? Compare charging with the EV vs gas tool.
How we calculate the cost to drive this route
No black box here. The formula is simple: trip cost = (distance ÷ your MPG) × price per gallon. For the Seattle to Portland run we use a driving distance of about 175 miles and a blended pump price of roughly $4.35 a gallon across the states you cross. Swap in your own numbers for an exact figure. Our gas cost calculator does the arithmetic instantly, and the road trip cost calculator handles multi-stop trips.
Where the numbers come from: pump prices trace to the U.S. Energy Information Administration (EIA) weekly retail survey, refreshed on our state price pages every business day. Distances reflect the main highway route between the two cities. You can read exactly how each figure is sourced on our methodology and sources pages, and track longer trends on the gas price history page.
Calculations reviewed by Alex Morgan · Last reviewed: July 12, 2026
Frequently Asked Questions
How much does it cost in gas to drive Seattle to Portland?
About $25 one-way for a 30-MPG car at $4.35 a gallon, or roughly $51 round-trip.
How far is Seattle to Portland?
Roughly 175 miles on I-5, about three hours without heavy traffic.
Is gas cheaper in Oregon or Washington?
The two are usually close, and both sit above the national average. Check the live tracker before your trip, since the gap shifts week to week.
Is the train cheaper than driving?
For a solo traveler, Amtrak Cascades can beat driving once you add parking. Groups splitting gas usually favor the car.
What would an EV cost on this drive?
Charging at home, often just $7 to $9 one-way thanks to cheap Northwest electricity, well under the gas cost.
The bottom line
Driving from Seattle to Portland costs most people between $19.03 and $38.06 in gas one-way, depending on the vehicle and the price on the day, with round-trip simply double that. The two levers you actually control are which car you take and where you fill up. Nail both, and you keep real money in your pocket.
Before you go, run your exact numbers in the gas cost calculator and check today’s live prices. Planning the whole route with stops? The road trip cost calculator maps every fill-up before you turn the key.