Why is the fleet average not a simple average of MPG values?

Fuel economy must be averaged harmonically, weighted by distance driven. A simple average overstates efficiency because a low-MPG vehicle uses disproportionately more fuel per mile. This tool uses the correct distance-weighted harmonic mean.

What does "weighted average" mean here?

Vehicles that drive more miles contribute more to the fleet average. A vehicle driving 20,000 miles per year has twice the influence of one driving 10,000 miles, reflecting its actual fuel consumption share.

Can I mix gasoline and diesel vehicles?

Yes. Enter the fuel economy for each vehicle in the same unit (MPG or L/100km). For a mixed fleet, use an average fuel price that reflects your actual mix of fuel costs.

How do I convert L/100km to MPG?

Divide 235.214 by the L/100km value to get US MPG. For example, 8 L/100km equals about 29.4 MPG. The tool handles conversions automatically when you switch units.

Is any data sent to a server?

No. All calculations happen entirely in your browser. Nothing is transmitted or stored outside your device.

Fuel Economy Fleet Calculator

Enter each vehicle's fuel economy and annual mileage to get weighted fleet average MPG and total fuel cost.

Settings

Unit System

Fuel Price ($/gal)

Vehicles

Vehicle Name MPG Miles/yr

Fleet Average

—

MPG

Annual Fuel Cost

—

all vehicles

Total Distance

—

miles/yr

Total Fuel Used

—

gallons/yr

Per-Vehicle Breakdown

Add vehicles on the left to see the breakdown.

Summary

This fleet fuel economy calculator lets you add any number of vehicles, each with its own fuel efficiency and annual mileage, and instantly shows the weighted-average fleet MPG (or L/100km) along with total annual fuel costs. Unlike simple averages, the tool uses harmonic-mean weighting so fuel economy is calculated correctly by distance driven. Switch between US (MPG, dollars per gallon) and metric (L/100km, price per liter) units at any time.

How it works

Choose your preferred unit system: US (MPG) or Metric (L/100km).
Add each vehicle by entering its name, fuel economy, and annual mileage.
Enter the current fuel price per gallon or per liter.
The calculator instantly computes the weighted-average fleet fuel economy.
Total annual fuel cost and per-vehicle fuel cost are displayed in real time.
Click "Add Vehicle" to include more vehicles or remove any row with the trash icon.

Use cases

Compare the fuel costs of replacing an old fleet vehicle with a newer, more efficient model.
Report overall fleet fuel efficiency to management or investors.
Budget annual fuel expenses for a company vehicle pool.
Evaluate whether switching part of a fleet to hybrid or EV reduces overall cost.
Track how routing or load changes affect effective fleet fuel consumption.
Justify fuel surcharge calculations for delivery or logistics businesses.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu