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.
Travel, Fuel & Unit Conversion
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.
Calculator
Working calculator
Live result26.7 mpg320 mi ÷ 12 US gal = 26.666667 mpg exact · rounded to 0.1 mpg · 3.75 gal/100 mi · trip fuel cost 45.00 at 3.75/gal · 0.14 per mile · planned 500 mi needs about 18.75 gal (70.31)
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.
This is the method behind the answer, so the result can be checked rather than simply trusted.Visual grid
This number is one point on a larger pattern
MPG is not just a final answer. It is a step on a line: before and after, input and output, assumption and result.
Micro-timehours, minutes, shiftsHuman scaledays, weeks, projectsMacro-timemonths, years, calendars
InputFormulaResult
26.7 mpgCalculationTime keeps the path visible: the input, the method and the final number belong together.
CalculationTime
MPG Calculation Report
26.7 mpg320 mi ÷ 12 US gal = 26.666667 mpg exact · rounded to 0.1 mpg · 3.75 gal/100 mi · trip fuel cost 45.00 at 3.75/gal · 0.14 per mile · planned 500 mi needs about 18.75 gal (70.31)
Inputs
- Miles driven
- 320 mi
- Fuel used
- 12 US gal
- Fuel price
- 3.75 per US gal
- Planned distance
- 500 mi
- MPG rounding increment
- 0.1 mpg
Method
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.
- 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.
Assumptions
- 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.
Notes
Use this space on the printed report for client, supplier, classroom, job-location, measurement, quote or approval notes.
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
- 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.
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.
Related calculators
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.