Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Net IFTA tax due (+) / refund (−)
$0
Fleet average MPG
6.28
Gallons consumed (by miles)
4,300
Net taxable gallon gap
0
Total fuel spend this quarter
$16,770
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How to use this
- 1Enter total miles this quarter (mi).
- 2Enter gallons purchased (all jurisdictions) (gal).
- 3Enter average ifta tax rate ($/gal).
- 4Enter average price paid per gallon (pre-tax basis) ($/gal).
- 5Read your net ifta tax due (+) / refund (−) on the right — it updates as you type.
- 6Hit Share to keep the scenario or send it to someone.
About this calculator
IFTA reconciles fuel tax so you pay based on miles driven in each state, not just where you bought fuel. This simplified estimator handles the two-state case that trips up most single-truck operators: miles driven and gallons purchased in a home state versus everything else, using an average tax rate difference. It computes the fleet MPG for the quarter, the tax-paid gallons versus tax-owed gallons implied by miles driven, and the net amount due or refundable. Real IFTA filings break this out per jurisdiction with published quarterly rates that change, so treat this as a planning estimate to budget cash for filing, not a substitute for your state's IFTA return.
Worked example
Using the values the calculator loads with:
Inputs
- Total miles this quarter: 27000 mi
- Gallons purchased (all jurisdictions): 4300 gal
- Average IFTA tax rate: 0.32 $/gal
- Average price paid per gallon (pre-tax basis): 3.9 $/gal
Results
- Net IFTA tax due (+) / refund (−): $0
- Fleet average MPG: 6.28
- Gallons consumed (by miles): 4,300
- Net taxable gallon gap: 0
- Total fuel spend this quarter: $16,770
What each field means
Inputs
- Total miles this quarter (mi)
- The total miles this quarter used in the calculation, measured in mi. Starts at 27000 mi so you have a working example on load.
- Gallons purchased (all jurisdictions) (gal)
- The gallons purchased (all jurisdictions) used in the calculation, measured in gal. Starts at 4300 gal so you have a working example on load.
- Average IFTA tax rate ($/gal)
- The average ifta tax rate used in the calculation, measured in $/gal. Starts at 0.32 $/gal so you have a working example on load.
- Average price paid per gallon (pre-tax basis) ($/gal)
- The average price paid per gallon (pre-tax basis) used in the calculation, measured in $/gal. Starts at 3.9 $/gal so you have a working example on load.
Results
- Net IFTA tax due (+) / refund (−)
- Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Fleet average MPG
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Gallons consumed (by miles)
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Net taxable gallon gap
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Total fuel spend this quarter
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
Why would I owe tax if I already paid tax at the pump?
You paid tax to whatever state you bought fuel in, not the states where you actually drove. If you buy most fuel in a low-tax state but run lots of miles through high-tax states, your base jurisdiction return shows a balance due to true it up.
Is this exact enough to file with?
No. This is a planning estimate using one blended tax rate. Real IFTA returns require per-jurisdiction miles, per-jurisdiction gallons purchased, and each state's published quarterly rate — use your ELD's IFTA report or trucking accounting software for the actual filing.
What if I get a negative number?
A negative net tax means you likely overpaid at the pump relative to miles driven in high-tax jurisdictions, which typically results in a credit or refund on your IFTA return rather than a payment.
How can I lower my IFTA exposure?
You can't avoid the tax obligation, but you can smooth cash flow by fueling proportionally to where you actually drive miles, and by setting aside roughly your average net tax rate times monthly miles into a separate account each month.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). IFTA Fuel Tax Estimate Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/ifta-fuel-tax-estimate
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/ifta-fuel-tax-estimate" target="_blank" rel="noopener">IFTA Fuel Tax Estimate Calculator — RevenueLab</a> (2026).</p>
Source: [IFTA Fuel Tax Estimate Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/ifta-fuel-tax-estimate) (2026).