⛽ Fuel Distance Calculator

How Far Can You Drive on a Tank?

Enter the gallons in your tank and your real-world MPG, and the calculator gives your driving range in miles. Add the gas price for cost per mile and fill-up cost. The range is only as honest as the MPG you enter: use your measured average, not the window sticker.

The Formula

Fifteen gallons at 28 MPG is 420 miles of range. At $3.50 a gallon, cost per mile is $3.50 / 28 = $0.125, shown as $0.13, and the fill-up costs $52.50. Twelve gallons at 22 MPG is 264 miles. Simple multiplication, but doing it before a road trip beats discovering the answer at the fuel light.

Worked Example

A crossover with a 15-gallon tank averaging 28 MPG: 420-mile range, $0.13 per mile at $3.50/gal. Planning a 380-mile drive? The math says one tank barely covers it, so plan a stop around mile 300 instead of gambling on fumes. That is the entire value of the calculator in one scenario.

Measuring Your Real MPG

Fill the tank, reset the trip odometer, drive normally, refill, and divide trip miles by gallons pumped. Do it three times and average: single-tank figures swing with pump shutoff differences. Compare against the EPA rating on fueleconomy.gov, but trust your own number for range math. Short trips and winter idling can easily cost 20 percent versus the rating.

The Reserve Rule

Running the tank dry risks the fuel pump, which uses gasoline for cooling, and leaves you stranded. Treat the last 1-2 gallons (or the last eighth of the gauge) as untouchable reserve: subtract it from the tank size before calculating range. A 420-mile theoretical range becomes a 364-mile practical one, and you will never walk.

Stretching Your Range

Speed is the biggest lever: fuel economy typically peaks around 50 mph and falls fast past 65. Steady cruising beats stop-and-go by 15-30 percent, proper tire pressure is worth a few percent, and a roof box can cost 10+ percent at highway speed. Small changes compound across a full tank.

The EV Equivalent: MPGe

Electric cars skip gallons entirely, but the EPA's MPGe keeps comparisons possible: 33.7 kWh of electricity equals the energy in one gallon of gas. A car rated 120 MPGe travels 120 miles on 33.7 kWh. To compare running costs, convert: at $0.17/kWh, 33.7 kWh costs $5.73, so 120 MPGe is like driving 120 miles on $5.73 of "fuel." Against a 28 MPG gas car at $3.50/gal ($0.13/mile), the EV's $0.05/mile is the number that matters.

Worked Example: Two Cars, One 500-Mile Trip

A crossover at 25 MPG and a hybrid at 38 MPG, gas at $3.60 a gallon, 500 miles to cover. The crossover needs 500 / 25 = 20 gallons, costing 20 x 3.60 = $72.00. The hybrid needs 500 / 38 = 13.2 gallons, costing 13.2 x 3.60 = $47.37. The hybrid saves $24.63 on this one trip. Stretch that to 15,000 miles a year: the crossover burns 600 gallons ($2,160), the hybrid burns 394.7 gallons ($1,421.05), and the annual gap is $738.95. That is the honest way to price a hybrid premium against fuel savings.

Range version: a 13.2-gallon tank at 31 MPG gives 13.2 x 31 = 409 miles of theoretical range. Subtract a 2-gallon reserve and the practical number is 11.2 x 31 = 347 miles. Planning a 450-mile drive? The math says one tank cannot do it, so schedule the stop near mile 300 with the gauge still healthy instead of coasting on fumes past mile 380.

The Fuel Gauge Lie: Why the Last Quarter Vanishes

Fuel gauges are not linear, and the last quarter always falls faster than the first. The float arm in the tank swings through an arc, so equal gauge movement does not mean equal gallons. Manufacturers also calibrate the bottom of the gauge pessimistically on purpose: the low-fuel light typically triggers with 2 to 3 gallons still in the tank, worth 50 to 80 miles, because a driver who runs dry blames the car, not the math.

Distance-to-empty displays add another layer of fiction. They compute from your recent average MPG, so a week of city driving makes the DTE read low on the highway, and a highway week makes it read optimistic around town. They also hide a buffer the car never shows you. The fix is boring and works: trust the odometer. Reset the trip meter at every fill-up, know your real per-tank range from the calculator, and treat the gauge as a rough hint, not an instrument.

Worked Example: 400-Mile Road Trip

A car with a 14-gallon tank averaging 32 mpg has a theoretical range of 448 miles. For a 400-mile trip, that looks comfortable, but the honest math reserves a buffer: most drivers refuel at a quarter tank, so usable range is 336 miles and the trip needs one fuel stop. Plan the stop around mile 250 to 300, where stations are plentiful, rather than stretching to mile 400 on fumes past the last exit with services.

Winter changes the numbers. Cold starts, winter-blend gasoline, and heater use typically cut mpg by 10 to 15 percent. That 32 mpg car becomes a 28 mpg car in January, and the 448-mile range shrinks to 392. The calculator's range figure assumes your measured mpg; if you measured it in July, derate by 10 percent for a January trip or measure again in winter.

Measuring Your Real MPG

Fill the tank completely, reset the trip odometer, drive normally until near empty, then fill completely again. Divide miles driven by gallons added: 380 miles on 12.4 gallons = 30.6 mpg. Do this three tanks in a row and average them; a single tank is noisy because fill levels vary. Dashboard readouts are typically optimistic by 2 to 5 percent, so the pump-and-odometer method is the one to trust.

MPG is not constant, and the variation is the point of measuring. Pure highway at 65 mph might give 36; the same car in city traffic gives 24. For range planning, use the mpg matching the trip type. A highway trip planned on a blended average leaves you short, because the city miles in the average do not exist on the interstate.