IFTA calculator
Enter the miles you ran and the fuel you bought in each jurisdiction, with that quarter's rates, and this works out fleet mpg, taxable gallons, your tax-paid credits and what you owe — with surcharge jurisdictions handled properly. Free, no account, nothing leaves your browser.
IFTA calculator
Add a row per jurisdiction you ran in. Rates come from the official matrix for the quarter you are filing — this does not guess them. Everything stays in your browser.
| Jurisdiction | Miles | Gallons bought | Rate $/gal | Surcharge |
|---|
The calculation, in four steps
- Fleet mpg. Total miles ÷ total gallons, everywhere, across the whole fleet. One number for the quarter.
- Taxable gallons per jurisdiction. Miles in that jurisdiction ÷ fleet mpg. This is the fuel you are treated as having burned there, whether or not you bought it there.
- Tax due. Taxable gallons × that jurisdiction's rate for the quarter.
- Credit. Gallons you actually bought there × the same rate. Owed minus credit is your net — negative means a refund.
That is the whole of IFTA. You pay fuel tax to the jurisdictions you drove through rather than the ones you happened to fuel in, and the quarterly return settles the difference.
Why fuel stops move the number
The tax follows your miles, so buying cheap fuel in a low-tax jurisdiction does not dodge the tax on miles run elsewhere — it just changes whether you pay at the pump or on the return. What it does change is your cash: buy everything in low-tax states and you will owe at quarter end; buy in high-tax states and you will be carrying a credit.
The saving that is real is the base price of the diesel, not the tax component — which is why the regional spread matters more than the tax rate. See what a gallon actually costs by region.
The rest of it
| Quarter | Period | Return and payment due |
|---|---|---|
| Q1 | January – March | 30 April |
| Q2 | April – June | 31 July |
| Q3 | July – September | 31 October |
| Q4 | October – December | 31 January |
Questions
How is IFTA calculated?
Four steps. Add up every mile you ran and every gallon you bought across all jurisdictions, and divide to get your fleet mpg. Divide each jurisdiction's miles by that mpg to get the gallons you are taxed on there. Multiply by that jurisdiction's rate for the quarter to get the tax owed. Then subtract the tax you already paid at the pump in that jurisdiction. The difference is what you owe or are owed.
Is this IFTA calculator free?
Yes, and there is no account. It runs entirely in your browser — no miles, gallons or rates are sent anywhere.
Why do I have to type in the tax rates?
Because they change every quarter for every jurisdiction, and a calculator that quietly used last quarter's rates would produce a wrong return with your name on it. The official matrix is published by IFTA, Inc. each quarter — see IFTA tax rates for how to read it.
What is fleet mpg and why does it matter?
Total miles divided by total gallons, across the whole fleet and all jurisdictions — not the mpg for one truck or one state. Every jurisdiction's taxable gallons are derived from it, so an error in fleet mpg is an error in every line of the return.
What are surcharge jurisdictions?
IN, KY, VA charge a surcharge on top of the normal fuel tax. It is not collected at the pump, so you get no credit for gallons bought there — the surcharge line is always money owed. Tick the surcharge box on a row and the calculator handles it that way.
Do I still file if I didn't run anywhere?
Yes. A zero return is still due every quarter while your licence is active. Missing one costs the same $50 minimum penalty as missing a real one — see IFTA penalties.