IFTA Calculator

The formula, written out

IFTA is not complicated. What trips people up is the order: fleet MPG comes from the entire quarter across every jurisdiction, and only then is each jurisdiction settled against that single figure. Working it out state by state in isolation gives the wrong answer every time. Here is how to calculate IFTA taxes for a quarter, in that order:

1. Fleet MPG = total miles in all jurisdictions ÷ total gallons purchased in all jurisdictions.
2. Taxable gallons in a jurisdiction = taxable miles there ÷ fleet MPG. This is the fuel you are treated as having burned there.
3. Net taxable gallons = taxable gallons − tax-paid gallons you actually bought there.
4. Tax due = net taxable gallons × that jurisdiction's rate. A negative figure is a credit.
5. Surcharge, where it applies = taxable gallons × the surcharge rate, with no credit for purchases.
6. Net position = everything added together. Credits in one jurisdiction offset tax owed in another.

The idea underneath is simple. You pay fuel tax where you burn the fuel, not where you buy it. Buying cheap in a low-tax state and running the miles in a high-tax state does not avoid anything; it just moves the payment from the pump to the quarterly return.

A worked example

A truck runs 9,000 miles in a quarter and buys 1,200 gallons. Fleet MPG is 9,000 ÷ 1,200 = 7.50.

In one jurisdiction it ran 1,800 miles and bought 100 gallons. Taxable gallons there are 1,800 ÷ 7.50 = 240. Net taxable gallons are 240 − 100 = 140. At a rate of $0.29 that is $40.60 owed.

In another it ran 900 miles and bought 300 gallons: a cheap fuel stop on a short leg. Taxable gallons are 900 ÷ 7.50 = 120. Net is 120 − 300 = −180, so at $0.24 that is a credit of $43.20.

Those two net out to a small credit before the rest of the quarter is added. That is the entire mechanism, repeated across every jurisdiction you ran in.

How to get your miles by state

IFTA miles by state come from your ELD or your trip records, not from a route estimate. Many ELDs and telematics systems export a quarterly jurisdiction report listing the miles run in each state, and that report is the quickest way to fill in the rows above. Check it covers every truck on the license for the whole quarter before you trust the total.

Without one, a paper trip sheet does the same job. Record the odometer at the start and end of the trip and at each state line, along with the route, and add the miles up per jurisdiction at quarter end. It takes longer, and it is exactly what an auditor wants to see.

Route planners and online state mileage tools, including the route tool on this page, are useful for checking a trip that looks wrong, but they tell you the route a truck should have taken. An audit asks what it did take, so a planner's figure is a cross-check and not a record. When you finish, the state miles should add up to the miles on your odometer readings. If they do not, find the gap before you file.

How the route miles are worked out

The route tool finds a sensible truck route between your stops and adds up the miles on it by state and province. Type a city and state or a ZIP code, add stops in the order you ran them, and tick round trip if the truck came back the same way. The button under the result drops each state's miles into its row, so several trips build up the quarter, and the tax rates fill in as the rows appear.

It runs on your own device. The road network is a plain file your browser downloads once, about half a megabyte, and the routing happens in this tab. No town, ZIP code or route is sent anywhere, which is the same promise the rest of the calculator makes.

We tested it on 40 lanes it had never seen, against two independent routing engines, OSRM and Valhalla, and measured the gap to whichever engine came closer.

On main freight lanes the miles land close to both engines. On small-town lanes a route can run long when a road the truck would use is missing from the network: the worst lane, Ely, Nevada to Cedar City, Utah, came out 34% high. The split between states held up too. On 33 of the 40 lanes, less than 5% of the miles landed in a different state than Valhalla's truck route put them.

Two good corridors can split the same trip very differently. Dallas to Chicago comes out at 924 miles through Oklahoma and Missouri. Add a stop at Little Rock and it is 970 miles through Arkansas, which puts different states on your IFTA return. If the result crosses a state your truck did not, add a stop on the road you ran.

The tool does not know weight limits, low bridges, hazmat routes or seasonal closures, so it is not a truck routing or permit tool. Passenger-only parkways were taken out by name. The road data was compiled in October 2020, so a road opened since then is missing, and Mexico is left out. A ferry crossing is not counted in the miles, and miles in Alaska, Washington, DC or the Canadian territories are shown but not added, because those are not IFTA members.

Road network: North American Roads, National Transportation Atlas Database, Bureau of Transportation Statistics. Town locations: GeoNames, under CC BY 4.0. ZIP code locations: U.S. Census Bureau gazetteer.

The records the arithmetic depends on

A calculator is only as good as what goes into it, and IFTA record-keeping is where audits are won or lost. Distance records need to show, per trip: the date, where it started and ended, the route, beginning and ending odometer readings, total trip miles, the miles broken down by jurisdiction, and which vehicle and licensee it belonged to.

Fuel records need the date, the seller's name and location, the number of gallons, the fuel type, the price or total, and the vehicle it went into. A receipt missing the vehicle number is a receipt an auditor can disallow, which turns tax-paid gallons into gallons you cannot claim credit for.

What to keep, for how long, and what auditors actually look at is covered in the IFTA filing guide, along with the four quarterly deadlines and what happens when one is missed.

Where the numbers usually go wrong

• Mixing up miles and gallons columns. It sounds implausible until you have typed fifty rows. An implausible fleet MPG is usually this, and the calculator flags it.
• Counting fuel bought in a jurisdiction you did not run in. Gallons are claimed where they were purchased, but the miles have to exist. A fuel stop just over a state line with no miles recorded there stands out.
• Missing receipts. Every disallowed receipt reduces your tax-paid gallons and increases what you owe. Chase them before you file, not after.
• Forgetting a jurisdiction entirely. Short runs through a corner of a state still count. Total miles on the return should reconcile to total miles on your logs.
• Rounding your own way. The return rounds fleet MPG to two decimals and uses that one figure for every jurisdiction, then works in whole gallons. A spreadsheet that keeps every decimal will not match it to the cent, so the calculator shows both: the exact figures, and the net tax as the return works it out.
• Assuming Oregon works like everywhere else. Oregon runs a weight-mile tax rather than a diesel fuel tax, so its treatment on an IFTA return is not the same as its neighbours. Check the current instructions rather than pattern-matching.

Mileage taxes this calculator does not cover

Four states charge a weight-distance tax that sits outside IFTA, so a clean IFTA return does not settle them. Each runs its own registration, reports and schedule, and the thresholds below are the ones trade compliance sources publish, so confirm yours with the state before you run there.

These taxes are based on distance rather than fuel, so nothing on the rows above touches them. If you run these states often, carry the cost as its own line in the cost per mile calculator, because it is a real cost of running those miles that an IFTA credit will never offset.

Using the calculator

Add a row per jurisdiction and enter the miles you ran and the gallons you bought there. Choose the quarter and fuel, and the tax rate fills in for diesel and gasoline. Each row shows its own taxable gallons, net gallons and amount as you type, and the summary at the bottom gives the fleet MPG and the net position. If a jurisdiction levies a surcharge, that rate lands in the surcharge column and is calculated on taxable gallons without credit, which is how surcharges work. Take the miles you file from your ELD or your logs: this IFTA mileage calculator can estimate a trip's miles by state with the route tool, but those estimates are for planning and cross-checks.

The fleet MPG it works out is the honest number to use elsewhere, too: the fuel surcharge calculator and the trucking cost per mile calculator both ask for it, and a quarter's real figure beats the one on the dealer's spec sheet.

Export the CSV and open it in a spreadsheet to check line by line against what you are about to file. The file includes the fleet MPG and every intermediate figure, so a disagreement with your return is quick to trace.

Nothing is uploaded: the calculation, the route miles and the CSV are all built in your browser, and unlike the document generators this one is not saved to an account. Nothing is kept between visits, so export before you close the tab.

Limitations

This is a working calculation, not a filed return and not tax advice. It does not know your base jurisdiction's rules, does not handle jurisdiction-specific exemptions, and does not calculate interest or penalties on a late filing. When a rate changes mid-quarter it flags the jurisdiction and gives each period its own row, but dividing the miles and gallons between them is up to you. It also cannot tell whether the miles and gallons you typed match your records.

File through your base jurisdiction, and check the arithmetic against their form before you submit.

Common questions