Free IFTA fuel tax calculator
Quick quarterly estimate. Enter total miles + total gallons + average tax rate; we compute fleet MPG and indicative tax base. Use the full calculator for the real per-state breakdown.
Quarterly estimate
- Fleet MPG
- 6.67
- Consumed (gal)
- 3,000
- Estimated tax base
- $960.00
This is a rough estimate using the average tax rate you provide. Actual IFTA owed depends on per-jurisdiction tax rates and jurisdiction-by-jurisdiction miles. Use the full IFTA calculator for the real per-state breakdown.
Sources
- International Fuel Tax Agreement (IFTA) - IFTA, Inc. governance
- 49 USC §14302 - IFTA federal authorization
Common questions, plainly answered.
Fleet MPG is total miles driven divided by total gallons of diesel purchased across all vehicles in your IFTA-registered fleet for the quarter. The IFTA audit math uses fleet MPG to apportion total gallons consumed across each jurisdiction's mileage.
The full IFTA calculator at /tools/ifta-calculator handles per-jurisdiction miles and gallons, applying the actual published IFTA Inc. tax-rate matrix to each row. This lightweight version skips the per-state breakdown - useful when you want a quick estimate without entering each jurisdiction.
No. IFTA returns require the per-jurisdiction breakdown. This calculator gives you a back-of-envelope number to know roughly what to budget for the quarter; you still file with your base jurisdiction using their actual return form.
Across most US states the diesel IFTA tax rate runs $0.20–$0.45 per gallon. The 2026 average is roughly $0.32. Pennsylvania, California, and Illinois are at the high end ($0.55+); Mississippi, Oklahoma, and Texas are at the low end ($0.20–$0.22).
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