GSCalculate

Gas Mileage / MPG Calculator

Calculate real-world miles per gallon from distance driven and fuel used. See L/100 km, cost per mile, and how you compare to a static US average — free and private.

Reviewed / updated August 4, 2026

Your inputs

miles

Miles since the last fill-up (odometer difference)

gallons

Gallons to refill the tank (from the pump receipt)

USD/gal

Optional — unlocks cost per mile for this tank

Result

Fuel economy

26.7 MPG

280.0 mi ÷ 10.50 gal

L/100 km
8.8
km per liter
11.34
US avg benchmark
25.4 MPG
Cost per mile
$0.13
This fill-up cost
$36.23

26.7 MPG is near a static US average benchmark of ~25.4 MPG. Small changes in speed and tire pressure still move the needle.

Same tank, different miles

What MPG would look like if this fill-up covered a shorter or longer stretch.

MilesMPG
24022.9
28026.7
32030.5

Suggested next steps

  • Use the Fuel Cost Calculator with this MPG to estimate your next trip’s pump total.
  • Log a few more fill-ups — one tank can swing with hills, weather, or short trips.
  • Pair with the Trip Cost Calculator when you want fuel plus a simple per-person road-trip split.

How the MPG calculation works

  1. Miles driven — odometer change since the last full fill-up
  2. Gallons used — volume pumped to return to full
  3. MPG = miles ÷ gallons
  4. L/100 km ≈ 235.215 ÷ MPG
  5. Optional cost per mile = price per gallon ÷ MPG

A small what-if table shows how MPG would look if the same gallons covered fewer or more miles (for example, a shorter week of commuting). A rule-based note compares your result with a static US light-vehicle average (~25.4 MPG) and points you to the Fuel Cost and Trip Cost calculators in this cluster.

Worked example

You drive 280 miles on 10.5 gallons at $3.45/gallon:

  1. MPG = 280 ÷ 10.5 ≈ 26.7 MPG
  2. L/100 km ≈ 235.215 ÷ 26.7 ≈ 8.8
  3. Cost per mile ≈ 3.45 ÷ 26.7 ≈ $0.13
  4. Fill-up cost ≈ 10.5 × 3.45 ≈ $36.23

That MPG sits slightly above a ~25.4 MPG US average benchmark, so each dollar of fuel covers a bit more road than a typical light vehicle in this static comparison.

Methodology and notes

All math runs in your browser. One tank is noisy — average several fill-ups before changing habits. For trip fuel budgets, paste this MPG into the Fuel Cost Calculator; for a broader road-trip split, use the Trip Cost Calculator.

Frequently asked questions

MPG = miles driven ÷ gallons used. Reset your trip odometer (or note the mileage) at a full tank, drive normally, then refill and divide the miles by the gallons pumped. This tool does that division instantly and also shows L/100 km.

Related tools

Related calculators — live tools and upcoming pages for internal linking.