How do I calculate annual fuel cost?

Divide the miles you drive in a year by the mpg, then multiply by the price per gallon. 12,000 miles at 30 mpg is 400 gallons, and at 3.50 a gallon that is 1,400.00. A month is the year divided by 12, 116.67 here, and a week is the year times 7 divided by 365.25 days, 26.83.

Where do I find my annual mileage?

Take two odometer readings a year apart, from service or inspection records or your own notes, and subtract the earlier one. If you only know a typical month, the monthly page takes that instead.

How much would a more efficient car save in a year?

Switch on Second vehicle and enter the other car's economy. The Difference row shows the saving a year over the same mileage: at 12,000 miles and 3.50 a gallon, 30 mpg against 45 mpg is 1,400.00 against 933.33, a saving of 466.67.

Annual Fuel Cost Calculator

Enter the distance you drive in a year, the vehicle's fuel economy and the price you pay, and the page returns the yearly fuel cost with the monthly and weekly figures beside it. It opens on 12,000 miles a year at 30 mpg and 3.50 a gallon: 400 gallons and 1,400.00 a year. Distance, economy and price each take metric, US or UK units.

Yearly fuel cost1,400.00400 US gal over 12,000 miles a year

Distance a year

Efficiency

Measured in

Fuel price

Quoted

Sharing

Compare

Second vehicle

Enter the price in whatever currency you buy fuel in. The answer comes back in the same one, because the arithmetic never touches an exchange rate.

Fuel neededa year
400 US gal (1,514.165 L)
Per weeka year × 7 ÷ 365.25 days
26.83
Per montha year ÷ 12
116.67
Per yearfuel only, the distance you entered
1,400.00
Per persona year, one person
1,400.00
Per mile and per kmthe same money over two rulers
0.1167 per mile, 0.0725 per km
The workingevery conversion, in full
12,000 mi ÷ 30 mpg = 400 US gal; 400 US gal × 3.50 = 1,400.00; 1,400.00 ÷ 12 = 116.67 a month; 1,400.00 × 7 ÷ 365.25 = 26.83 a week

Two gallons, and one unit that runs backwards. Choose the gallon used by your fuel price and efficiency figure. L/100km measures fuel per distance, so a lower number means less fuel used, and it multiplies where mpg divides. Every conversion the answer needs is written into the working above with the constant it used, so you can check which gallon went where.

Common questions

How do I calculate annual fuel cost?: Divide the miles you drive in a year by the mpg, then multiply by the price per gallon. 12,000 miles at 30 mpg is 400 gallons, and at 3.50 a gallon that is 1,400.00. A month is the year divided by 12, 116.67 here, and a week is the year times 7 divided by 365.25 days, 26.83.
Where do I find my annual mileage?: Take two odometer readings a year apart, from service or inspection records or your own notes, and subtract the earlier one. If you only know a typical month, the monthly page takes that instead.
How much would a more efficient car save in a year?: Switch on Second vehicle and enter the other car's economy. The Difference row shows the saving a year over the same mileage: at 12,000 miles and 3.50 a gallon, 30 mpg against 45 mpg is 1,400.00 against 933.33, a saving of 466.67.

Exact arithmetic on the numbers entered: distance divided by efficiency, times price. Real consumption varies with speed, load and weather, so treat the result as the figure your own inputs imply.