CalculationTime

MPG Calculator

Calculate miles per gallon, gallons used, fuel cost and emissions-style fuel notes from distance, fuel volume and price for road trips, fleet logs, reimbursement records and classroom worksheets, with a printable mileage report.

Live math canvas

Your numbers, formula and explanation together

MPG Calculator: 835.85 miles per US gallon with gallons per 100 miles, trip cost and planned fuel estimate. MPG Calculator uses the declared inputs to produce a transparent default result. Miles driven: 320 mi; Fuel used: 12 US gal; Fuel price: 3.75 per US gal; Planned distance: 500 mi; primary comparison: 320 and 12.

Formula applied

The exact method behind this answer

CalculationTime keeps the method visible so the number can be checked instead of blindly trusted.

MPG = miles driven ÷ US gallons used. Gallons per 100 miles = gallons used ÷ miles driven × 100. Trip fuel cost = gallons used × fuel price per gallon. Planned gallons = planned miles ÷ MPG.
  1. Apply the formulaMPG = miles driven ÷ US gallons used. Gallons per 100 miles = gallons used ÷ miles driven × 100. Trip fuel cost = gallons used × fuel price per gallon. Planned gallons = planned miles ÷ MPG.835.85 miles per US gallon with gallons per 100 miles, trip cost and planned fuel estimateMPG Calculator uses the declared inputs to produce a transparent default result. Miles driven: 320 mi; Fuel used: 12 US gal; Fuel price: 3.75 per US gal; Planned distance: 500 mi; primary comparison: 320 and 12.

Your live breakdown

Current inputs in the calculation

These values come from the controls above and update when the calculator changes.

Miles driven
320 mi
Enter the trip distance or odometer difference in miles.
Fuel used
12 US gal
Enter fuel used in US gallons. Use litres-to-gallons first if your receipt is in litres.
Fuel price
3.75 per US gal
Optional price per gallon for a trip cost and reimbursement note.
Planned distance
500 mi
Optional future distance for an estimated fuel and cost projection.
MPG rounding increment
0.1 mpg
Use 0.1 mpg for ordinary fuel logs or 0.01 for worksheets.

Resulting answer

835.85 miles per US gallon with gallons per 100 miles, trip cost and planned fuel estimate

MPG Calculator uses the declared inputs to produce a transparent default result. Miles driven: 320 mi; Fuel used: 12 US gal; Fuel price: 3.75 per US gal; Planned distance: 500 mi; primary comparison: 320 and 12.

Answer
835.85 miles per US gallon with gallons per 100 miles, trip cost and planned fuel estimate
Live support
MPG Calculator uses the declared inputs to produce a transparent default result. Miles driven: 320 mi; Fuel used: 12 US gal; Fuel price: 3.75 per US gal; Planned distance: 500 mi; primary comparison: 320 and 12.

Assumptions used

What this answer assumes

Best for road-trip planning, fuel receipts, fleet logs, mileage reimbursement notes, personal car comparisons and classroom unit-rate worksheets where the distance, gallons and price need to stay visible.

  • Fuel volume is treated as US liquid gallons, not imperial gallons or litres.
  • Distance is entered in statute miles from an odometer, map distance or trip log.
  • The result describes observed fuel economy for the entered trip; weather, traffic, tyre pressure, load, fuel blend, terrain and driving style can change real-world MPG.
  • Fuel price is optional planning arithmetic before taxes, discounts, reimbursement rules, card fees or fleet accounting adjustments.
  • For official fuel-economy labels, emissions reporting, tax records or employer reimbursement, use the required official method and keep original receipts.

Master’s Tip

How to use the result well

Master’s Tip: print the odometer start/end or receipt note beside the result. MPG is only useful when the distance and gallons came from the same trip window, not from a partial fill or mixed record.

Printable record

What belongs in the saved calculation

Save the inputs, result, formula, assumptions, page URL and date together so the calculation can be reviewed later.

Miles driven
320 mi
Enter the trip distance or odometer difference in miles.
Fuel used
12 US gal
Enter fuel used in US gallons. Use litres-to-gallons first if your receipt is in litres.
Fuel price
3.75 per US gal
Optional price per gallon for a trip cost and reimbursement note.
Planned distance
500 mi
Optional future distance for an estimated fuel and cost projection.

Embeddable calculator

Embed this calculator

Copy a clean iframe version with the required CalculationTime attribution link built in.

Formula

MPG = miles driven ÷ US gallons used. Gallons per 100 miles = gallons used ÷ miles driven × 100. Trip fuel cost = gallons used × fuel price per gallon. Planned gallons = planned miles ÷ MPG.

Worked example

For 320 miles and 12 US gallons, MPG = 320 ÷ 12 = 26.6667 mpg. Gallons per 100 miles = 12 ÷ 320 × 100 = 3.75 gal/100 mi. At $3.75 per gallon, the trip fuel cost is 12 × 3.75 = $45.00.

Professional note

Master’s Tip: print the odometer start/end or receipt note beside the result. MPG is only useful when the distance and gallons came from the same trip window, not from a partial fill or mixed record.

Regional and unit assumptions

Standard or basis: US miles per US liquid gallon. One US liquid gallon is 231 cubic inches, and MPG differs from litres per 100 kilometres and imperial miles per gallon.

Assumptions and limitations

Methodology & Accuracy

How this calculator is checked

CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.

Formula used

MPG = miles driven ÷ US gallons used. Gallons per 100 miles = gallons used ÷ miles driven × 100. Trip fuel cost = gallons used × fuel price per gallon. Planned gallons = planned miles ÷ MPG.

Standard or basis

Standard or basis: US miles per US liquid gallon. One US liquid gallon is 231 cubic inches, and MPG differs from litres per 100 kilometres and imperial miles per gallon.

Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.

Master's Tip

Master’s Tip: print the odometer start/end or receipt note beside the result. MPG is only useful when the distance and gallons came from the same trip window, not from a partial fill or mixed record.

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These cards are resolved from calculator data, category context and live-route status so the page links to useful next steps without hand-built link clutter.

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Questions

How do I calculate MPG?

Divide miles driven by US gallons used. For example, 320 miles ÷ 12 gallons = 26.67 mpg.

What is gallons per 100 miles?

Gallons per 100 miles shows fuel consumed over a fixed distance. It is calculated as gallons used ÷ miles driven × 100, so lower is better.

Why is my calculated MPG different from the car sticker?

Sticker or official ratings use controlled test procedures. Your trip MPG can change with traffic, speed, load, weather, terrain, tyres, fuel blend and measurement quality.

Can I use litres in this MPG calculator?

This page expects US gallons. Convert litres to US gallons first, or use a litres-per-100-kilometres calculator when working entirely in metric units.

What should I print for a mileage record?

Print miles driven, gallons used, fuel price, MPG, gallons per 100 miles, trip cost, planned fuel estimate, formula, assumptions, page URL, date and notes from the receipt or odometer log.

Calculation note

Miles per gallon is a unit-rate record: how far a vehicle travelled for each US gallon of fuel. It is familiar in the United States, while many other countries use litres per 100 kilometres, a consumption measure where lower values are better.

MPG is a distance-per-fuel rate

The calculation divides distance by fuel volume, so a larger MPG means more miles from each gallon. The inverse view, gallons per 100 miles, can make fuel consumption and cost comparisons easier.

Trip records need matched inputs

A trustworthy MPG note uses miles and fuel from the same period. Partial fills, forgotten odometer readings or mixed city/highway trips can explain surprising results.

Printable mileage notes support real decisions

A filed report with distance, gallons, price and assumptions is useful for road-trip budgets, reimbursement conversations, fleet checks and student unit-rate exercises.

Sources and further readingU.S. Department of Energy and EPA — FuelEconomy.govEPA — Fuel economy label and rating informationNIST Handbook 44 Appendix C — General Tables of Units of Measurement