Gallons needed and total fuel cost for any trip — from distance, MPG, and pump price.
Every road trip, commute, and delivery route has one unavoidable line item: fuel. Our free Fuel Cost Calculator turns three numbers you already know — trip distance, your car’s miles per gallon (MPG), and the price at the pump — into the two numbers that matter: how many gallons you will burn and exactly what the trip costs.
The math is simple division and multiplication, but the value is in the planning. A 300-mile weekend trip at 28 MPG and $3.50 a gallon costs exactly $37.50 — knowing that before you leave changes how you budget the weekend. Fleet managers run the same calculation thousands of times a month; commuters use it to compare cars; families use it to decide whether driving beats flying.
Enter your numbers and get an instant, itemized answer — gallons needed, total fuel cost, and cost per mile — with no sign-up and nothing in the way.
MPG is not a fixed property of a car; it is partly a habit. Aggressive acceleration, idling, roof cargo, under-inflated tires, and short cold-engine trips all drag real-world MPG below the sticker number. That is why the calculator asks for your number: the average you actually observe. Highway cruising at steady speed is the most efficient regime most drivers ever see; stop-and-go traffic is the least.
Cost per mile is the great equalizer. Two cars with different MPGs become directly comparable when reduced to dollars per mile. At $3.50 a gallon, 28 MPG costs $0.125 per mile while a 40 MPG hybrid costs $0.0875 per mile. Over 12,000 miles a year that gap is $450 — the number that decides whether a hybrid pays for itself. Key terms:Distance divided by efficiency gives fuel; fuel times price gives money. Keep units consistent — miles with MPG, kilometers with liters per 100 km — and the answer is exact. Round gallons up slightly when planning, because nobody wants to arrive on fumes.
A family drives 300 miles to a cabin. Their SUV averages 28 MPG; gas is $3.50 a gallon.
One tank or two? A 16-gallon tank holds the 10.71 gallons with comfortable margin — no mid-trip fuel stop needed. The cost-per-mile figure also settles the drive-versus-bus debate: a $90-per-person bus fare for four people is $360, while the round-trip drive costs about $75. Driving wins by a landslide.
A courier drives 850 miles a week in a sedan averaging 32 MPG, with gas at $3.40 a gallon.
Her per-mile reimbursement is $0.67, so fuel eats $0.106 of it and the rest covers depreciation, insurance, and maintenance — exactly the decomposition a gig driver needs to know whether the work pays. A 10 percent MPG improvement from better tires and gentler driving would save her roughly $470 a year.
Chicago to Nashville is 470 miles. Driving: 470 ÷ 30 MPG = 15.67 gallons × $3.55 = $55.63 in fuel, plus $18 in tolls = $73.63. Flying: a $189 fare + $60 airport parking + a $45 rental-car day = $294 per person. For two travelers, driving costs $73.63 total versus $588 flying — a $514 difference the fuel calculation makes concrete in seconds.
Second scenario: the commuter’s car choice. Option A is keeping a 24 MPG sedan; option B is buying a 42 MPG hybrid that costs $4,000 more. Annual commute: 14,000 miles. Option A fuel: 14,000 ÷ 24 × $3.50 = $2,041.67 a year. Option B fuel: 14,000 ÷ 42 × $3.50 = $1,166.67 a year. The $875 yearly saving repays the $4,000 premium in about 4.6 years — a payback period the calculator’s per-mile figures make trivial to derive.
Third scenario: the road-trip budget. A 1,200-mile round trip at 26 MPG and $3.65 a gallon: 1,200 ÷ 26 = 46.15 gallons × $3.65 = $168.46. Add $32 in tolls and the driving budget is $200.46. Setting that aside before departure is the difference between a relaxed trip and credit-card surprise.
Fourth scenario: the fleet manager. Forty vans, each driving 25,000 miles a year at 18 MPG and $3.60 a gallon: per van, 25,000 ÷ 18 × $3.60 = $5,000 a year, or $200,000 for the fleet. A 2 MPG improvement across the fleet saves over $20,000 annually — which is why fleet buyers obsess over efficiency ratings.
One pattern worth internalizing: cost per mile turns every driving decision into arithmetic. Once you know your number — say $0.13 — every optional trip has a price tag: the 40-mile detour costs $5.20. Most people never compute it; you just did.
A brief history of the gallon: Americans buy fuel by the gallon because the U.S. gallon — 231 cubic inches, a descendant of the old English wine gallon — survived metrication. Most of the world prices fuel by the liter, which is why the same car’s efficiency is quoted in MPG in Ohio and L/100 km in Ontario. The arithmetic is identical; only the units change. And the price boards you see? They descend from the first drive-in filling stations of the 1910s, when Standard Oil began posting prices to lure motorists off the curb pumps.
Worked scenario — the moving truck: a family rents a box truck for a 620-mile move. The truck gets 10 MPG; diesel is $4.10. Fuel: 620 ÷ 10 = 62 gallons × $4.10 = $254.20. That single line is nearly a third of the move’s total cost — which is why the rental quote’s “fuel not included” footnote matters more than the daily rate. They budget $275 to be safe and arrive with $18 to spare.
Edge cases and pro tips: towing or a loaded roof box can cut MPG by 25 percent or more — recompute with the loaded figure, not the empty one. Winter blends and cold starts cost another 10 percent in northern states. Mountainous routes burn more than flat ones even at the same distance, because climbing is never fully repaid by descending. Pro tip: fill up before crossing into high-tax states; apps that track station prices pay for themselves on one long trip. And if your “trip” is a daily commute, multiply the one-way result by 2, then by your working days — the annual number is always the shocking one.
When a fuel cost calculator is the wrong tool: if you need the full cost of a trip — tolls, parking, food, hotels — use the Trip Cost Calculator instead; fuel is only one line item. If you are comparing total car ownership costs, you need depreciation and insurance too, not just fuel. And if your question is “what is my car’s actual MPG?” rather than “what does this trip cost?”, the MPG Calculator answers that directly — then bring its result back here.
Fuel cost: gallons = distance / MPG; total = gallons x price per gallon; cost per mile = total / distance. Example: 300 mi / 28 MPG = 10.71 gal x $3.50 = $37.50 ($0.125/mi). Use real-world MPG, double distance for round trips. Source: Sigma Calculator, Fuel Cost Calculator, https://sigmacalculator.net/automotive-calculators/fuel-cost-calculator-2/
Cite this page as: Fuel Cost Calculator, Sigma Calculator, https://sigmacalculator.net/automotive-calculators/fuel-cost-calculator-2/
Last updated: October 12, 2026