What Is the US Gasoline Tax Calculator?
This calculator applies to the United States. It estimates the total excise tax you pay on gasoline, combining the federal rate (18.4 cents per gallon as of the current tax schedule) with your state's per-gallon rate. State gasoline taxes vary widely, so enter the rate for your state to get an accurate figure.
How to Use It
Enter the number of gallons you purchased, your state gasoline tax in cents per gallon, and the federal rate (pre-filled at 18.4 cents). The calculator returns the total tax paid in dollars, broken down into federal and state portions, plus the combined per-gallon rate.
The Formula Explained
Gasoline excise taxes are levied per gallon, not as a percentage of price. The total tax is simply the gallons multiplied by the sum of the federal and state cents-per-gallon rates, then divided by 100 to convert cents to dollars:
$$\text{Tax} = \text{Gallons} \times \frac{\text{Federal cents} + \text{State cents}}{100}$$
Worked Example
Suppose you buy 15 gallons in a state with a 30.0 cent gasoline tax. The combined rate is \(18.4 + 30.0 = 48.4\) cents/gallon. Total tax = $$15 \times \frac{48.4}{100} = \$7.26$$ of which $2.76 is federal and $4.50 is state.
FAQ
Is the federal gas tax always 18.4 cents? The federal excise tax on gasoline has been 18.4 cents per gallon since 1993. Diesel is 24.4 cents.
Does this include sales tax? No. Some states also apply general sales tax on top of excise tax; this tool covers per-gallon excise tax only.
Where do I find my state rate? State gasoline tax rates are published by each state's department of revenue and range from roughly 9 to over 60 cents per gallon.
