Washington Gas Tax Calculator
2026Calculate total gas tax per gallon in Washington, including the federal excise tax of $0.184/gal and WA state fuel taxes. Compare Washington gas and diesel tax rates for 2026.
Written and reviewed by Konstantin Iakovlev · Methodology · Updated
Fuel Needed
1.0 gal
Trip Cost
$4.10
Annual Cost
$1,066.00
Fuel Cost Breakdown
| Total Distance | 30.0 miles |
| Fuel Needed | 1.00 gallons |
| One-Way Cost | $4.10 |
| Trip Cost | $4.10 |
| Weekly Cost | $20.50 |
| Monthly Cost | $88.77 |
| Annual Cost | $1,066.00 |
Disclaimer: This calculator is for informational purposes only and does not constitute tax, financial, or legal advice. Results are estimates based on the information you provide and current rates. Always consult a qualified tax professional or financial advisor for advice specific to your situation.
How much is gas tax in Washington?
Every gallon of gasoline pumped in Washington carries two layers of tax: a federal excise tax of 18.4¢ per gallon (24.4¢ for diesel) collected by the IRS, and a state-level fuel tax of approximately 49.4¢ per gallon that funds Washington highway, bridge, and transit projects. Combined, that's roughly 67.8¢ per gallon in 2026.
State gas tax rates vary widely — from under 10¢/gal in Alaska to nearly 60¢/gal in California and Pennsylvania. Some states, including Washington, periodically adjust the rate via fuel-index formulas tied to wholesale prices or inflation, so the figure can drift mid-year. Many states also stack on smaller environmental, underground-storage-tank, or pre-paid sales-tax fees that aren't always shown at the pump but are baked into the posted price.
For a typical 12-gallon fillup in Washington, you contribute about $8.14 to combined road and federal infrastructure funds before any sales tax. Use the calculator above with your local pump price and tank capacity for an exact breakdown of pre-tax fuel cost vs. tax burden.
Washington fuel-tax history, indexing, and where the money goes
- Diesel state tax (2026)
- 49.4¢ per gallon
- Last increase
- 2016 (final 4.9¢ step under Connecting Washington 2015)
- Indexed?
- No — fixed until legislative action
- Where revenue goes
- Motor Vehicle Account (constitutionally protected since 1944)
Washington raised its gas tax from 37.5¢ to 49.4¢ over 2015–2016 under the $16B Connecting Washington package, an 11.9¢ phased increase. The 18th Amendment to the WA Constitution dedicates fuel-tax revenue exclusively to highway purposes — preventing diversion to transit or general fund. Washington has the highest combined EV ($225) + hybrid ($75) surcharge in the country. The state also runs an annual "transportation electrification fee" rolled into EV registration.
Washington Tax Rates (2026)
| Federal Gas Tax | $0.184/gal |
| State Sales Tax | 6.5% |
| State Income Tax | None |
| Avg. Property Tax Rate | 0.94% |
Gas tax — frequently asked questions
What is the Washington gas tax in 2026?
Washington's gasoline excise tax is 49.4¢/gallon (unchanged since 2016) — the third-highest in the country after California and Pennsylvania. Diesel is taxed at the same 49.4¢/gallon rate. The rate was raised from 37.5¢ to 49.4¢ over 2015–2016 under the $16B Connecting Washington package. Revenue flows constitutionally to the Motor Vehicle Account under the 18th Amendment to the Washington Constitution (1944), preventing diversion to transit or general fund.
Does Washington index its gas tax to inflation?
No — Washington's gas tax is not automatically indexed. The 49.4¢ rate has been frozen since 2016 (the final 4.9¢ step under the Connecting Washington package). The legislature has debated indexing repeatedly but the 18th Amendment's strict highway-only dedication and political opposition to automatic increases have kept the rate flat. Washington compensates by having the highest combined EV fee ($225) plus hybrid fee ($75) in the country.
Where does Washington gas tax revenue go?
Washington's 18th Amendment to the State Constitution (1944) restricts fuel-tax revenue exclusively to highway purposes — preventing any diversion to transit, ferries, or the general fund. Revenue funds the Washington State Department of Transportation (WSDOT) for highway construction and preservation, the State Patrol on highways, and ferries (treated as marine highways). Cities and counties receive distributions for local road work. WA also runs an annual transportation electrification fee bundled into EV registration.