How much gas tax do I pay per year in Montana?

At Montana's 33¢/gallon rate: if you drive 10,000 miles/year at 28 MPG, you pay $118/year; at 15,000 miles, $177/year; at 20,000 miles, $236/year in Montana state gas tax.

What is the federal gas tax?

The federal gasoline excise tax is 18.4¢ per gallon and has not changed since 1993. It applies on top of every state's gas tax. On a gallon of gas in ${s.name} at ${s.centsPerGallon}¢ state tax, total combined tax is ${(s.centsPerGallon + 18.4).toFixed(1)}¢/gallon — about ${Math.round(((s.centsPerGallon + 18.4) / (AVG_GAS_PRICE * 100)) * 100)}% of a $${AVG_GAS_PRICE.toFixed(2)} gallon.

How does the gas tax compare to other states?

Montana's 33¢/gallon state tax compares to a national average of about 32¢/gallon. The lowest state gas tax is Alaska at 8.95¢; the highest is California at 59.6¢. Illinois (67¢ effective) exceeds California when local taxes are included.

Montana Gas Tax 2025 — 33¢/Gallon | KalkWise

By the KalkWise Editorial Team Reviewed for accuracy Updated June 2026

What is the montana gas tax 2025 — 33¢/gallon?

In short

Montana's state gas tax is 33¢ per gallon in 2025 — about 9% of a $3.50 gallon of gas. A typical driver doing 15,000 miles/year at 28 MPG buys ~536 gallons and pays roughly $177/year in Montana state gas tax alone (plus the federal 18.4¢/gal).

This page shows Montana's 2025 state gas tax rate and calculates how much you pay in state fuel tax based on your annual mileage and fuel economy. The figure does not include the federal excise tax (18.4¢/gallon) or any local county/city fuel taxes.

How to use this calculator

1The Montana state gas tax of 33¢/gallon is already filled in.
2Enter your annual miles driven.
3Enter your vehicle's fuel economy (MPG).
4See your annual gallons used and state gas tax paid.

The formula

annual state tax=state rate (¢)100×gallons/yr

annual federal tax=18.4100×gallons/yr

total gas tax=annual state tax+annual federal tax

Annual gallons = miles ÷ MPG. State gas tax paid = gallons × 33¢ per gallon. Total gas cost = gallons × pump price per gallon (includes federal + state tax + retail margin).

cents/gallon: — Montana state excise tax per gallon: 33¢
annual gallons: — Annual miles ÷ fuel economy (MPG)
state tax paid: — Annual gallons × state cents per gallon ÷ 100
federal tax: — 18.4¢/gallon federal excise — same in every state

Worked example

The scenario

15,000 miles/year, 28 MPG, Montana state gas tax 33¢/gallon.

gives

The result

Annual gallons = 15,000 ÷ 28 = 536 gallons. State gas tax = 536 × $0.3300 = $177/year. Total gas cost at $3.50/gal = $1875/year (of which $177 is Montana tax and $99 is federal tax).

Common use cases

Understanding how much of your gas bill goes to Montana fuel taxes
Comparing gas tax costs between states before relocating
Estimating annual fuel costs for a new vehicle purchase
Advocacy or understanding of transportation funding

Limitations & assumptions

The federal gas tax (18.4¢/gallon) is not included — it applies in addition to the state tax.
Local county or city gas taxes in Montana are not included; some areas charge additional surcharges.
Actual pump price varies by station, location, and crude oil markets — the tax is fixed but the retail price fluctuates.
Diesel, flex-fuel, and other fuel types may have different tax rates.

Frequently asked questions

The Montana state gas tax is 33 cents per gallon in 2025. Montana's gas tax is 33¢/gallon and has not been indexed to inflation, so its real value has declined over time.

Disclaimer: KalkWise calculators are provided for general informational and educational purposes only and do not constitute financial, investment, tax, or legal advice. Results are estimates based on the figures you enter and the assumptions described above. Actual outcomes will vary. Consult a qualified professional before making financial decisions.

Fuel Usage