Cost Per Mile Calculator
Where fuel tax lands in your cost per mile.
OpenIFTA Fuel Tax Calculator
One quarter, one row per jurisdiction. It computes the fleet miles per gallon, spreads gallons consumed across jurisdictions by miles, prices each at your rate and nets it against the tax you already paid at the pump there.
This quarter, by jurisdiction
Miles run and tax-paid gallons bought in each jurisdiction, plus that jurisdiction's current rate per gallon. Rates change quarterly — take them from the IFTA rate table for the quarter you are filing.
| Jurisdiction | Miles | Tax-paid gal | Rate $/gal | Remove |
|---|---|---|---|---|
- Total miles
- 14,900
- Total tax-paid gallons
- 1,700
- Fleet miles per gallon
- 8.76
| Jurisdiction | Taxable gal | Paid gal | Net |
|---|---|---|---|
| Base state | 935.6 | 1400.0 | -$130.04 |
| Neighbour A | 467.8 | 300.0 | $68.79 |
| Neighbour B | 296.6 | 0.0 | $96.41 |
Net tax owed
$35.16
Ready to file
What it checks
Fleet MPG is total miles divided by total gallons — across the whole fleet and the whole quarter, not per truck and not per trip. Taxable gallons in a jurisdiction are that jurisdiction's miles divided by the fleet MPG. Net is taxable minus tax-paid, times the rate. Positive is owed, negative is a credit.
A fleet MPG that comes out above about 9 or below about 4 usually means miles or gallons are missing, not that the trucks changed. Check the total before you check the jurisdictions.
Worked example
The default figures are a quarter with 14,900 miles and 1,700 gallons — a fleet MPG of about 8.8. The base state bought most of the fuel and ran most of the miles, so it nets close to zero. Neighbour A ran 4,100 miles on 300 gallons bought there, so it owes tax on roughly 165 gallons it consumed but did not pay for. Neighbour B bought nothing at all and owes on every gallon.
That is the whole shape of IFTA: you pay where you burn, not where you buy, and fuelling strategy moves the timing rather than the total.
Where the rules come from
IFTA is an agreement between jurisdictions, not a section of 49 CFR. The Articles of Agreement, the Procedures Manual and the Audit Manual are published by IFTA Inc, and your base jurisdiction administers them. Where a state adds its own requirement, the state wins for that state.
This tool implements the standard calculation. It does not carry the quarterly rate table, deliberately: a stale rate produces a confidently wrong number, and the current table is a click away in the source below.
Sources
- International Fuel Tax Agreement — Articles of Agreementread 2026-09-04