Gas mileage calculator (MPG calculator)

Gas mileage calculator: MPG (US and UK), L/100 km and km/L from odometer readings and fuel added, cost per mile, and a fill-up log with trend chart.

Обновлено 28 сентября 2026 г.Проверенные примеры: 6

Fuel economy (US)

mpg

Знаков после запятой: 1; До ближайшего, при равенстве — к чётной цифре

Fuel economy (UK): 38.2mpg
Fuel consumption: 7.39L/100 km
Kilometers per liter: 13.54km/L
Distance: 312mi / 502.1km
Fuel used: 9.8US gal / 37.1L
Fuel cost: $43.90
Cost per mile: $0.141
Cost per km: $0.087
CO₂ from the fuel: 87.1kg

312 mi on 9.8 gal is 31.8 mpg, the same as 38.2 UK mpg, 7.39 L/100 km, or 13.54 km/L. The fuel cost $43.90, $0.141 per mile.

Fuel cost per 100 mi at $4.48 per gallon

Как выполняется расчёт S

Distance since the last fill-up
$24{,}812 - 24{,}500 = 312\ \text{mi}$
Distance per unit of fuel
$\frac{312\ \text{mi}}{9.8\ \text{gal}} = 31.8367\ \text{mi/gal}$
Convert to the other units
$\text{US mpg} = \frac{312.00\ \text{mi}}{9.8\ \text{gal}} = 31.84,\quad \text{L/100 km} = \frac{100 \times 37.097}{502.12} = 7.39$
1 mi = 1.609344 km, 1 US gal = 3.785411784 L, 1 UK gal = 4.54609 L (exact, NIST SP 811).
Fuel cost
$9.8 \times 4.48 = 43.90;\quad \frac{43.90}{312\ \text{mi}} = 0.1407\ \text{per mi}$
CO₂ from the fuel
$9.8\ \text{gal} \times 8{,}887\ \text{g/gal} \div 1000 = 87.1\ \text{kg}$
EPA emission factor for gasoline.

О калькуляторе: Gas mileage calculator (MPG calculator)

Fuel economy is the distance driven divided by the fuel it took to refill the tank. Enter the odometer reading at your last fill-up and today's, or the trip distance, and the gallons or liters you just added. The result is shown as US mpg, UK mpg, L/100 km and km/L, with the fuel cost per mile and per kilometer and the CO₂ the fuel released.

With the defaults, 312 miles on 9.8 gallons is 31.8 mpg. At $4.48 a gallon, the US average for regular in the week of 21 September 2026 (EIA), that tank cost $43.90, or 14.1 cents a mile. The fill-up log takes one line per fill-up and gives the average over all of them, each tank's figure and a trend line.

The method assumes you fill to the same level each time, since a partly filled tank makes one reading high and the next one low. The average of a log is total miles over total fuel, which is not the same as averaging the per-tank mpg.

Примеры с решением

312 miles on 9.8 US gallons at $4.48

Calculate from: One fill-up
Distance in: миля
Fuel in: галлон США
Distance from: Odometer readings
Odometer at last fill-up: 24,500
Odometer now: 24,812
Fuel added to refill the tank: 9.8
Fuel price per gallon or liter: 4.48

Fuel economy (US): 31.8 mpg
Fuel economy (UK): 38.2 mpg
Fuel consumption: 7.39 L/100 km
Kilometers per liter: 13.54 km/L
Fuel cost: 43.90
Cost per mile: 0.141
CO₂ from the fuel: 87.1 kg

Источник проверки: Python decimal: 312/9.8 = 31.8367 mpg; ×4.54609/3.785411784 = 38.2343 UK mpg; 100×9.8×3.785411784/(312×1.609344) = 7.3882 L/100 km; 9.8×8.887 kg = 87.09 kg (EPA factor)

fueleconomy.gov worked example

Calculate from: One fill-up
Distance in: миля
Fuel in: галлон США
Distance from: Odometer readings
Odometer at last fill-up: 32,645.1
Odometer now: 33,001.3
Fuel added to refill the tank: 13.5
Fuel price per gallon or liter: 4.48

Fuel economy (US): 26.4 mpg
Distance: 356.2 mi

Источник проверки: fueleconomy.gov, Calculate your own gas mileage: 33,001.3 − 32,645.1 = 356.2 miles; 356.2 ÷ 13.5 = 26.4 mpg

Trip of 520 km on 38.4 liters

Calculate from: One fill-up
Distance in: километр
Fuel in: литр
Distance from: Trip distance
Distance driven: 520
Fuel added to refill the tank: 38.4
Fuel price per gallon or liter: 1.85

Fuel consumption: 7.38 L/100 km
Kilometers per liter: 13.54 km/L
Fuel economy (US): 31.9 mpg
Fuel cost: 71.04
Cost per km: 0.137

Источник проверки: Python decimal: 38.4×100/520 = 7.3846; 520/38.4 = 13.5417; 235.2145833/7.384615 = 31.8520 US mpg; 38.4×1.85 = 71.04

UK: 410 miles on 42 liters

Calculate from: One fill-up
Distance in: миля
Fuel in: литр
Distance from: Trip distance
Distance driven: 410
Fuel added to refill the tank: 42
Fuel price per gallon or liter: 1.40

Fuel economy (UK): 44.4 mpg
Fuel economy (US): 37.0 mpg
Fuel consumption: 6.37 L/100 km

Источник проверки: Python decimal: 410/(42/4.54609) = 44.3785 UK mpg; 410/(42/3.785411784) = 36.9528 US mpg; 4200/(410×1.609344) = 6.3653

Вопросы

How do you calculate gas mileage?

Fill the tank and note the odometer. At the next fill-up, subtract the old reading from the new one and divide by the gallons it took to fill the tank again. Driving 312 miles and adding 9.8 gallons gives 312 ÷ 9.8 = 31.8 mpg. The US Department of Energy's fueleconomy.gov uses the same full-tank method in its worked example: 356.2 miles on 13.5 gallons is 26.4 mpg.

How do you convert mpg to L/100 km?

Divide 235.215 by US mpg, or 282.481 by UK mpg. The constants come from 100 × 3.785411784 L ÷ 1.609344 km for the US gallon and 100 × 4.54609 ÷ 1.609344 for the imperial gallon. So 31.8 US mpg is 7.4 L/100 km, and 7.4 L/100 km is 38.2 UK mpg. Because the relationship is a division, halving L/100 km doubles mpg.

Why should I average mpg over several fill-ups?

Pumps shut off at slightly different levels, so fuel left out of one fill-up is added at the next, making one tank read high and the next low. fueleconomy.gov warns that an estimate is not accurate unless the tank is filled completely. Dividing the total miles of all fill-ups by their total gallons cancels most of that error. Averaging the per-tank mpg figures instead gives short tanks the same weight as long ones and overstates economy when the tanks vary.

How much CO₂ does a gallon of gas produce?

Burning one gallon of gasoline produces about 8,887 grams of CO₂, and a gallon of diesel about 10,180 grams, according to the US Environmental Protection Agency. A car averaging 31.8 mpg therefore emits about 280 grams of CO₂ per mile from its tailpipe. EPA's typical passenger vehicle, at 22.2 mpg and 11,500 miles a year, emits about 4.6 metric tons a year. The figure scales with fuel burned, so each mpg gained lowers emissions in proportion.

What is the cost per mile of driving?

Fuel cost per mile is the price per gallon divided by mpg: $4.48 ÷ 31.8 mpg is 14.1 cents a mile. That covers fuel only. The IRS business standard mileage rate, 76 cents a mile from 1 July 2026 (IR-2026-29), also covers depreciation, insurance, repairs and tires, so it is more than five times the fuel cost of this car.

Насколько точен «Gas mileage calculator (MPG calculator)»?

Точность зависит от введённых данных и допущений метода. Десятичная арифметика использует 50 значащих цифр, но оценки, численные методы и исходные данные могут быть менее точными; округление на экране не устраняет эти ограничения. Решённые примеры, проверенные по независимым источникам: 6. Например, «312 miles on 9.8 US gallons at $4.48» проверяется по источнику Python decimal: 312/9.8 = 31.8367 mpg; ×4.54609/3.785411784 = 38.2343 UK mpg; 100×9.8×3.785411784/(312×1.609344) = 7.3882 L/100 km; 9.8×8.887 kg = 87.09 kg (EPA factor).

Откуда взята методика?

US DOE / EPA fueleconomy.gov — Calculate your own gas mileage (My MPG); NIST SP 811 Appendix B.9 — gallon (US and imperial) and mile conversion factors; US EPA — Greenhouse gas emissions from a typical passenger vehicle (8,887 g CO₂ per gallon of gasoline).

Об этом калькуляторе

\text{mpg} = \frac{\text{odometer}_{\text{now}} - \text{odometer}_{\text{last fill}}}{\text{gallons added}},\qquad \text{L/100 km} = \frac{235.215}{\text{mpg (US)}}

Источники

Проверено по источникам

В калькулятор включены решённые примеры с ответами из независимых источников. Их количество: 6. Они входят в набор тестов, и вы также можете запустить их здесь.

Fuel cost per 100 mi at $4.48 per gallon

Distance since the last fill-up

Distance per unit of fuel

Convert to the other units

Fuel cost

CO₂ from the fuel