# Gas Mileage / MPG Calculator

Calculate your car's gas mileage in MPG and L/100km. Enter distance and fuel used to find your fuel efficiency and cost per mile.

## What this calculates

Track your vehicle's fuel efficiency with this gas mileage calculator. Enter the distance you traveled and the fuel consumed, and instantly see your efficiency in MPG, L/100km, and km/L. Supports both imperial and metric units with automatic conversion.

## Inputs

- **Distance Traveled** (miles) — min 0
- **Fuel Used** (gallons) — min 0.01
- **Unit System** — options: Miles / Gallons (US), Kilometers / Liters
- **Fuel Price (per unit)** ($/gal) — min 0 — Price per gallon or per liter

## Outputs

- **Miles Per Gallon (MPG)**
- **Liters per 100 km**
- **Kilometers per Liter**
- **Fuel Cost per Distance** (/mi) — formatted as currency
- **Fuel Cost per km** — formatted as currency

## Details

Knowing your actual gas mileage helps you:

  - Monitor vehicle health (declining MPG can indicate maintenance issues)

  - Compare fuel costs between vehicles

  - Budget accurately for road trips

  - Track the impact of driving habit changes

How to measure: Fill your tank completely, reset the trip odometer, drive normally, then fill up again. Divide the miles driven by the gallons added.

Conversion reference: 1 US gallon = 3.785 liters, 1 mile = 1.609 km. To convert MPG to L/100km: divide 235.215 by the MPG value.

## Frequently Asked Questions

**Q: What is a good MPG for a car?**

A: For a gasoline car, 25-30 MPG is average, 30-40 MPG is good, and 40+ MPG is excellent. Hybrid vehicles typically achieve 40-60 MPG, while electric vehicles have equivalent ratings of 90-130 MPGe.

**Q: How do I convert MPG to L/100km?**

A: Divide 235.215 by your MPG. For example, 30 MPG = 235.215 / 30 = 7.84 L/100km. Lower L/100km means better efficiency.

**Q: Why is my actual MPG lower than the EPA rating?**

A: EPA ratings are tested under controlled conditions. Real-world driving includes traffic, weather, and driving style variations. City driving typically yields 10-20% lower MPG than highway, and aggressive driving can reduce MPG by 15-30%.

**Q: Does AC reduce gas mileage?**

A: Yes, air conditioning can reduce fuel economy by 5-25%, depending on conditions. At low speeds, opening windows is more efficient. At highway speeds, AC is more efficient than the aerodynamic drag from open windows.

**Q: How often should I check my gas mileage?**

A: Check every few fill-ups to establish a baseline. A sudden drop of more than 10% could indicate issues like under-inflated tires, a dirty air filter, faulty oxygen sensor, or engine problems.

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Source: https://vastcalc.com/calculators/everyday/gas-mileage
Category: Everyday Life
Last updated: 2026-04-21