Fuel Cost Calculator
This fuel cost calculator answers one question: what will the gas cost? It covers road trips, monthly commutes, splitting a trip with friends, and comparing two vehicles on the same distance — and it covers fuel only, nothing else. Enter the distance, your vehicle's miles per gallon, and the gas price you actually pay (there are no live prices here; the price is always yours to enter), and it shows gallons used, total cost, and cost per mile with every step of the math.
Each mode asks only for the inputs it needs.
One-way or round-trip — just be consistent with the price you compare against.
Your vehicle's real-world mpg, not just the window-sticker figure. In compare mode this is vehicle A.
Enter the price you pay at your station. This calculator has no live gas prices.
Total fuel cost
70
- Gallons of fuel500 miles ÷ 25 mpg.
- 20gal
- Cost per mile$3.50 per gallon ÷ 25 mpg.
- 0.14
How it was calculated
- Gallons: 500 miles ÷ 25 mpg = 20.00 gallons.
- Cost: 20.00 gallons × $3.50 per gallon = $70.00.
- Cost per mile: $3.50 ÷ 25 mpg = $0.1400.
How it works
Gallons used = miles ÷ miles per gallon. A 500-mile trip in a car that gets 25 mpg burns 500 ÷ 25 = 20 gallons, no matter what gas costs.
Total fuel cost = gallons × price per gallon. Those 20 gallons at $3.50 a gallon cost 20 × $3.50 = $70. Change the price and only the second step changes.
Cost per mile = price per gallon ÷ mpg. At $3.50 and 25 mpg that is $3.50 ÷ 25 = $0.14 per mile — the single number that lets you compare any two vehicles or any two gas prices without redoing the whole trip.
Split mode divides the trip total equally: total ÷ people. Commute mode scales one day: (daily miles ÷ mpg × price) × commute days. Compare mode runs the same distance twice, once per vehicle, and subtracts: vehicle A cost − vehicle B cost = savings with vehicle B.
Worked examples
500-mile road trip: $70
A 500-mile trip at 25 mpg and $3.50 per gallon uses 500 ÷ 25 = 20 gallons, and 20 × $3.50 = $70.00. Cost per mile is $3.50 ÷ 25 = $0.14. Split four ways, each person pays $70.00 ÷ 4 = $17.50.
Monthly commute: $79.20
A 30-mile daily round trip at 30 mpg and $3.60 per gallon burns 30 ÷ 30 = 1 gallon a day, or $3.60 a day. Over 22 commute days that is $3.60 × 22 = $79.20 a month, at $0.12 per mile. Working from home one day a week (about 18 days instead of 22) drops it to $64.80.
How to measure
- Use your real-world mpg, not the window sticker: track one tank (miles driven ÷ gallons pumped) and you will usually land 1–3 mpg below the combined rating, which moves a 500-mile trip by several dollars.
- Enter the price at the station you will actually use. Prices vary by several dollars per gallon between states and even across town, and this calculator has no live prices — the number you type is the number it uses.
- Split by people, not by seats: if one rider is only joining for half the trip, split that leg separately instead of dividing the whole total by everyone who ever rode along.
- Compare vehicles on the same distance and the same gas price, or the comparison is meaningless. A hybrid only shows its saving when both cars drive the same 500 miles at the same $3.50.
- For a commute, count round-trip miles and real workdays. A 15-mile one-way commute is 30 miles a day, and 22 days is a standard full-time month — part-time or hybrid schedules need their own day count.
Assumptions & limitations
Planning estimate
- Fuel only. Tolls, parking, depreciation, insurance, and maintenance are NOT included — this page answers what the gas costs, not what the trip or the car costs overall. A future all-in cost tool would cover those; it is not linked here because it does not exist yet.
- No live gas prices. The price per gallon is always entered by you, so the result is only as current as the price you type. Example values on this page ($3.50, $3.60) are examples, not price quotes.
- MPG is treated as constant across the whole distance. Real driving mixes city and highway, and cold weather, hills, and loads all move mpg — so treat the result as a planning estimate, not a pump receipt.
- Split mode divides the total equally. It does not handle unequal shares (for example, a driver who pays extra) — for that, divide the total yourself from the per-person figure.
- All figures are estimates for planning a trip or a budget, not a quote, a reimbursement rate, or financial advice.
Frequently asked questions
Divide the gas price by your miles per gallon: cost per mile = price per gallon ÷ mpg. At $3.50 a gallon and 25 mpg, that is $3.50 ÷ 25 = $0.14 per mile. It is the most useful single number here because it scales to any distance — multiply it by any trip length to get that trip's fuel cost, and compare it across vehicles without redoing the whole trip.
A lot, and it is easy to see with this tool. On a 500-mile trip at $3.50 a gallon, an 18-mpg SUV burns 27.78 gallons for $97.22, while a 50-mpg hybrid burns 10 gallons for $35.00 — a $62.22 difference on one trip, or about $0.19 vs $0.07 per mile. Over 12,000 miles a year that gap is roughly $1,493. Use compare mode with your own two vehicles and your own gas price for your number.
No — deliberately. This page is fuel-only: gas in, dollars out. Tolls, oil changes, tires, insurance, and the car losing value are real trip and ownership costs, but they belong to an all-in cost calculation, not to a fuel calculation. Mixing them in would make the fuel number impossible to check against a pump receipt, so the scope stays narrow on purpose.
The price you will actually pay — the station near you, the grade you actually buy. This calculator has no live gas prices and never claims to know today's price. If your trip crosses states, either use an average of the prices along the route or run the trip twice, once per state price, and add the two totals.
Split mode takes the trip total and divides it equally among the number of people you enter: $70 split four ways is $17.50 each. It assumes everyone shares equally. If someone rides only part of the way, split that leg as its own trip instead of adding them to the full-trip headcount.