Gas Mileage Calculator - MPG, Fuel Economy & Gas Cost
Free online gas mileage calculator and vehicle fuel economy tracker. Calculate exact miles per gallon from odometer readings or distance traveled, compute trip fuel expenses, and compare two vehicles to evaluate 5-year and 10-year gas savings.
Gas Mileage Calculator (MPG & Fuel Economy)
Compute vehicle fuel efficiency, trip gas costs, and multi-vehicle annual fuel savings.
Trip & Fuel Details
Trip Cost Breakdown
Gas Mileage & Fuel Economy Guide: Miles Per Gallon (MPG), Liters/100km, and Cost Optimization
Vehicle fuel economy directly determines monthly transportation expenses and total cost of ownership. Calculating precise fuel economy requires tracking fuel volume against odometer intervals. This guide outlines how to compute MPG, convert to metric standards, and analyze multi-year fuel savings.
Mathematical Formulas for Fuel Economy
Miles Per Gallon (US): MPG = Total Trip Miles / US Gallons Consumed
Metric Fuel Consumption: L/100km = (Liters Consumed / Distance in Kilometers) × 100
Distance per Liter: km/L = Distance in Kilometers / Liters Consumed
Imperial MPG (UK): MPG (UK) = MPG (US) × 1.20095
Step-by-Step Instructions
Record Odometer or Trip Distance
Input miles or kilometers driven between fuel fill-ups (e.g. 350 miles on a full tank).
Enter Fuel Volume Added
Input the exact gallons or liters of gasoline/diesel pumped to refill the tank.
Enter Fuel Price Per Gallon/Liter
Input local fuel price (e.g. $3.65/gallon) to calculate total trip fuel expenditure.
Review Fuel Economy & Cost per Mile
Inspect calculated Miles Per Gallon (US MPG / UK MPG), Liters per 100 Kilometers (L/100km), Cost per Mile ($/mi), and total annual fuel budget.
Key Features & Capabilities
- Multi-standard fuel economy calculation: US Miles Per Gallon (`US MPG`), Imperial Miles Per Gallon (`UK MPG`), and Metric `L/100km`
- Trip cost calculator: computes total fuel cost and exact Cost per Mile / Cost per Kilometer (`$/mi` or `$/km`)
- Annual driving fuel expense projector based on weekly commute mileage and fuel price trends
- Vehicle comparison mode: compare two vehicles to calculate annual savings from upgrading to a higher-MPG car or hybrid
- Fuel range estimator calculating remaining driving distance from tank capacity and current MPG
- Instant real-time evaluation with zero server roundtrips
Frequently Asked Questions
What is the mathematical formula to calculate Miles Per Gallon (MPG)?
The formula is: `MPG = (Ending Odometer - Starting Odometer) / Gallons of Fuel Pumped`. For example, if you drive 360 miles and pump 12 gallons to refill your tank: `360 / 12 = 30 MPG`.
How do you convert US MPG to Liters per 100 Kilometers (L/100km)?
The conversion formula is: `L/100km = 235.215 / US MPG`. For example, a vehicle achieving 30 US MPG consumes `235.215 / 30 = 7.84 L/100km`. Note that with L/100km, lower numbers indicate superior fuel efficiency.
What is the difference between US MPG and UK (Imperial) MPG?
An Imperial gallon (used in the UK and Canada) is 20% larger than a US liquid gallon (`1 UK Gallon = 4.546 Liters`, whereas `1 US Gallon = 3.785 Liters`). Therefore, a car achieving 30 US MPG will achieve `30 * 1.20095 = 36.03 UK MPG`.
How can drivers improve real-world fuel economy?
Key factors that increase MPG by 10%–25% include: maintaining proper tire inflation pressure, avoiding aggressive acceleration and hard braking, removing excess cargo weight, keeping highway cruising speeds below 70 mph, and using cruise control.
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