The per-mile method
Trucking and delivery companies commonly calculate fuel surcharges per mile: (current fuel price − base fuel price) ÷ miles per gallon. The base is the fuel price your rates were built on; the current price is a published average — often the EIA weekly diesel price for trucking, or the monthly average for simpler local billing.
Example: a box truck gets 7 mpg. Your rates were set when diesel averaged $3.68, and it now averages $6.25 — $2.57 higher. The surcharge is $2.57 ÷ 7 = about $0.37 per mile. A delivery that accounts for 15 route miles carries a surcharge of about $5.51.
Per stop on multi-drop routes
When one truck makes 20 deliveries on a loop, each stop shares the route miles. Divide the day’s route miles by the number of stops (or allocate by distance or zone) and apply the per-mile surcharge to each stop’s share. Zone-based surcharges — a set amount for each delivery zone — are easy to publish and administer.
Percentage surcharges
Some shippers prefer a percentage of the freight charge. Work out the total extra fuel cost across your deliveries, divide by revenue, and publish a table that steps the percentage with the fuel price. Percentages are simple but less precise for very short or very long runs.
Regional prices and your own fuel cards
Fuel prices differ by region — the West Coast typically runs higher than the Gulf Coast. If you use a regional average, say which one. Your fuel-card statements are a good check on whether the published average tracks what you actually pay; if you consistently pay more, a published index still keeps the surcharge transparent, and the rest belongs in your base rate.
Set a base and a schedule
- Base price: the fuel price included in your rates — no surcharge below it.
- Source: name the index (for example, EIA on-highway diesel, U.S. average or your region).
- Update cadence: weekly for trucking-style contracts, monthly for local customers.
- Steps: round to steps (for example every 5 or 10 cents) so invoices stay predictable.
Don’t forget the rest
Driver wages, insurance, tires and maintenance aren’t fuel, and a surcharge shouldn’t carry them. Review your base delivery rates separately, or customers will see a surcharge that keeps creeping without explanation.
How to tell customers
Publish the formula, the base price and the index on your rate sheet, give 30 days’ notice before starting, and show the surcharge as its own invoice line. Customers rarely object to a surcharge they can check.
Fuel figures are U.S. Energy Information Administration monthly averages (regular gasoline $3.06 → $4.31 and on-highway diesel $3.68 → $6.25 a gallon, October 2025 → October 2026). Inflation is BLS CPI-U, up about 4.0% over the same year. Worked examples use illustrative costs — use your own.