What is the gas tax in Washington?

Washington's state gasoline excise tax is 49.4 cents per gallon, one of the highest in the country. On top of that, the federal excise tax adds 18.4 cents per gallon, for roughly 67.8 cents of fixed per-gallon tax before any local or carbon-related costs.

Does Washington's gas tax include the cap-and-invest cost?

No. This calculator counts only the fixed statutory excise taxes. Washington's cap-and-invest (carbon market) program adds further per-gallon cost at the pump, but it fluctuates with carbon-allowance prices and is not a flat excise, so it is excluded from this estimate.

How much gas tax do I pay per year?

It depends on how much you drive and your fuel economy. The annual mode divides your yearly miles by your MPG to get gallons, then applies both the 49.4-cent state and 18.4-cent federal rates. For example, 12,000 miles at 25 MPG burns 480 gallons and pays about $325 in combined fuel tax.

Is diesel taxed at the same rate?

Washington taxes diesel and other special fuels at rates that can differ from gasoline. This tool uses the gasoline excise rate, so use it as a gasoline estimate and check the diesel rate separately if you drive a diesel vehicle.

Why is Washington's gas tax so high?

Washington dedicates its high gasoline excise tax mostly to transportation projects and road maintenance, and it has no state income tax to fund those programs. The result is one of the highest state gas taxes in the United States.

Washington Gas Tax Calculator

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The Washington gas tax calculator shows the fuel tax built into every gallon you buy, splitting it into the state’s 49.4-cent excise tax and the 18.4-cent federal tax. Estimate it per fill-up or across a full year of driving.

How it works

Each gallon of gasoline in Washington carries two fixed excise taxes:

Washington state tax: $0.494 per gallon — among the highest state rates in the US.
Federal tax: $0.184 per gallon, the same nationwide.

The math depends on which mode you choose:

gallons (annual)  = annual miles / MPG
gallons (fill-up) = tank size in gallons

state tax   = gallons x 0.494
federal tax = gallons x 0.184
total tax   = state tax + federal tax

Example

Driving 12,000 miles a year in a car that gets 25 MPG:

Gallons: 12,000 / 25 = 480
State tax: 480 x $0.494 = $237.12
Federal tax: 480 x $0.184 = $88.32
Total fuel tax: $325.44 per year.

Tips and notes

Carbon cost is on top. Washington’s cap-and-invest program adds further per-gallon cost that this tool does not include, because it moves with allowance prices.
Diesel differs. This estimate uses the gasoline rate; check the diesel rate separately if needed.
Improve MPG to cut tax. Because fuel tax is per gallon, better fuel economy directly lowers what you pay — the annual mode makes that trade-off visible.
Rates can change. Confirm the current per-gallon rate with the Washington Department of Licensing before relying on the figure.