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Road trip fuel calculator
Put your trip distance, fuel economy, gas price and tank size in: a 300-mile trip at 30 mpg needs 10 gallons, $35.00 at $3.50 a gallon, on a 12-gallon tank with a 360-mile range and 0 refuel stops.
★ EVERYDAY · TRAVEL · ROAD TRIPS
Road Trip Fuel Calculator: 10 Gallons for a 300-Mile Trip
On the defaults — a 300-mile trip, 30 mpg, $3.50 a gallon, a 12-gallon tank — you need 10 gallons, $35.00, and 0 refuel stops. This is the road trip fuel tool: divide the trip by the economy, price the gallons, and check the tank range — a trip budgeted on gallons never runs dry on price.
What does road trip fuel needed 10 gallons, $35.00 mean?
It means a 300-mile trip in a 30 mpg car burns 10 gallons and costs $35.00 at $3.50 a gallon, and needs no refuel stop because the 12-gallon tank carries 360 miles — further than the trip itself, starting on a full tank. The gallons are the trip divided by the economy, the cost is the gallons times the price, and the stops are the trip divided by the tank range, rounded up, minus the starting tank. The cost is the budget line for the trip, while the stops are the plan on the road: a 600-mile trip on the same car needs 20 gallons, $70.00, and 1 stop, since one tank no longer covers it.
Output · formula · meaning
| Output | Formula | What it means |
|---|---|---|
| Gallons | distance ÷ mpg | 10 gallons — 300 ÷ 30. |
| Fuel cost | gallons × price | $35.00 — 10 × $3.50. |
| Range a tank | mpg × tank size | 360 mi — 30 × 12. |
| Refuel stops | trips tanks, minus the starting tank | 0 stops — 300 mi inside one 360 mi tank. |
Three things to check before you trust the number
First, use the real trip distance, not the straight-line distance: detours, city miles and the last ten miles to the cabin all burn fuel the map never counted. Second, use the car real economy, not the sticker figure: a loaded car at highway speed beats the sticker, and a car in traffic misses it, so 30 mpg on paper can be 25 mpg on the road — and 12 gallons instead of 10. Third, remember the stops assume a full tank at the start: a trip begun on half a tank stops once even inside one tank range. For the time side of the same trip, the drive vs public transit commute calculator compares driving with the alternative.
Worked example
300 mi trip, 30 mpg, $3.50 a gallon, 12 gal tank. Gallons: 300 ÷ 30 = 10 gallons. Cost: 10 × $3.50 = $35.00. Range: 30 × 12 = 360 mi a tank. Refuel stops: 300 mi inside one 360 mi tank, starting full, so 0 stops. In practice that means budgeting $35.00 for fuel and driving straight through, and filling up before leaving, since the return trip is another 10 gallons and another $35.00.
Every branch, checked
With a 450-mile trip instead of 300, the need rises to 15 gallons, $52.50, and 1 refuel stop, since the trip passes one full tank. With 25 mpg instead of 30, the need rises to 12 gallons, $42.00, on the same 300 miles, and the tank range falls to 300 mi. With $4.00 a gallon, the gallons stay 10 but the cost rises to $40.00, since price moves only the cost. With a 15-gallon tank, the gallons and cost stay 10 and $35.00, but the range rises to 450 mi, so the same trip still needs 0 stops with more margin. Distance, economy, price and tank each move the trip on their own, so a wrong economy figure is as costly as a wrong distance.
The reverses, worked backwards
The distance behind 10 gallons is 300 mi: at 240 mi the need is 8 gallons, $28.00 (240 mi, 30 mpg, $3.50 a gallon, 12 gal tank, 360 mi a tank, 0 refuel stops); at 600 mi it is 20 gallons, $70.00 (600 mi, 30 mpg, $3.50 a gallon, 12 gal tank, 360 mi a tank, 1 refuel stop). The economy behind 10 gallons is 30 mpg: at 25 mpg the need is 12 gallons, $42.00 (300 mi, 25 mpg, $3.50 a gallon, 12 gal tank, 300 mi a tank, 0 refuel stops); at 40 mpg it is 7.5 gallons, $26.25 (300 mi, 40 mpg, $3.50 a gallon, 12 gal tank, 480 mi a tank, 0 refuel stops). The price behind $35.00 is $3.50: at $3.00 the need is 10 gallons, $30.00 (300 mi, 30 mpg, $3.00 a gallon, 12 gal tank, 360 mi a tank, 0 refuel stops); at $4.00 it is 10 gallons, $40.00 (300 mi, 30 mpg, $4.00 a gallon, 12 gal tank, 360 mi a tank, 0 refuel stops). Each reverse moves one input and holds the rest, so the step is exactly one distance, economy or price change.
What the defaults assume
The defaults assume a 300-mile trip, a 30 mpg car, $3.50 a gallon, and a 12-gallon tank filled before leaving. They do not assume tolls, food, lodging or the return trip — a round trip doubles the gallons and the cost, and a car in traffic or loaded with luggage burns more than its sticker economy.
Who uses this
- A family planning a weekend drive: the $35.00 fuel line settles the trip budget before the bags are packed.
- A driver comparing cars for a long trip: the same maths at 25 and 40 mpg shows what economy is worth in dollars.
- A road-tripper planning stops: the tank range, not the trip length, decides where the first stop falls.
- A budgeter splitting trip costs: the gallons and cost per car, divided by passengers, give each share fairly.
Accuracy & limitations
The arithmetic is exact for the inputs entered; the judgement is the distance and the economy. Real trips add detours, city miles, hills and headwinds, and the pump price overrides any planning figure; a trip measured straight-line under-counts the gallons, and a sticker economy over-counts them on a loaded car. Treat 10 gallons and $35.00 as the planning budget for a 300-mile trip at 30 mpg and $3.50 a gallon, and carry a margin for the return leg and the price at the pump you actually use.
Cite this calculator
Bright Side Kit, “Road Trip Fuel Calculator: 10 Gallons for a 300-Mile Trip”, https://brightoolbox.com/road-trip-fuel-calculator/, accessed 3 November 2026. Students and researchers: cite the calculator name, the page URL and the date you used it, and quote the defaults (300 mi, 30 mpg, $3.50 a gallon, 12 gal tank) so the 10-gallon result can be checked.
Frequently asked questions
How much fuel does a 300-mile trip need?
10 gallons in a 30 mpg car, costing $35.00 at $3.50 a gallon, with 0 refuel stops on a 12-gallon tank, since the 360-mile range covers the trip.
How do I work out road trip fuel from a distance?
Divide the distance by the fuel economy for gallons, multiply by the price for cost, and multiply economy by tank size for the range. A 300-mile trip at 30 mpg is 10 gallons, $35.00 at $3.50 a gallon, 360 mi a tank.
How many refuel stops does a trip need?
Divide the trip by the tank range, round up, and subtract the starting tank. A 300-mile trip on a 360-mile range needs 0 stops, while a 600-mile trip needs 1 stop.
Does a bigger tank make a trip cheaper?
No — tank size changes only the range and the stops, never the gallons or the cost. A 15-gallon tank on the same trip still needs 10 gallons and $35.00, just with a 450-mile range.
Does gas price change how much fuel I need?
No — price changes only the cost. The same 300-mile trip needs 10 gallons at $3.00 or $4.00 a gallon; only the bill moves, from $30.00 to $40.00.
What if my car gets worse economy than the sticker?
Use the real figure: at 25 mpg the same trip needs 12 gallons and $42.00, and the tank range falls to 300 mi. The kilometers to miles converter handles the distance step for trips planned in kilometers.