Fuel Cost Calculator

Trip · Commute · Compare vehicles · US / Metric

Units

Distance & fuel

Distance (mi)

Efficiency (MPG)

Price ($/gal)

Passengers split

Round trip (2× distance)

Quick examples

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US: cost = (mi ÷ MPG) × $/gal. Metric: cost = (km × L/100km ÷ 100) × $/L.

⛽ Enter distance, efficiency, and fuel price to estimate trip cost.

Fuel Cost Formulas

Trip fuel cost needs distance, efficiency, and pump price. The same math powers one way trips, round trips, and commute estimates.

United States units

Gallons = miles ÷ MPG Cost = gallons × price per gallon Example: 300 ÷ 28 = 10.71 gal × $3.50 = $37.50 Cost per mile = price ÷ MPG = 3.50 ÷ 28 ≈ $0.125

Metric units

Liters = (km × L/100km) ÷ 100 Cost = liters × price per liter Example: (500 × 8.5) ÷ 100 = 42.5 L × $1.60 = $68.00

MPG ↔ L/100km

L/100km ≈ 235.215 ÷ MPG 30 MPG → 7.84 L/100km

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Round trip cost uses twice the one way distance before dividing by efficiency.

Quick Cost Reference

Miles	Gallons	Cost @ $3.50
50	1.79	$6.25
100	3.57	$12.50
200	7.14	$25.00
300	10.71	$37.50
500	17.86	$62.50

Table assumes 28 MPG and $3.50 per gallon. Change inputs above for your vehicle and local price.

How do you calculate fuel cost for a trip?

Divide miles by MPG for gallons, then multiply by price per gallon. Or use (km × L/100km ÷ 100) × price per liter.

What is cost per mile for gas?

Divide fuel price per gallon by MPG. Example: $3.50 ÷ 28 ≈ $0.125 per mile.

How to Use This Fuel Cost Calculator

Choose Trip for a single drive, Commute for daily and annual driving, or Compare to pit two efficiency and price combinations against the same distance. Toggle US or Metric so distance, efficiency, and price labels stay consistent.

Enter distance, efficiency, and pump price. Mark Round trip when you will return on the same route. Split by passengers when riders share fuel. Results update live with volume needed, total cost, cost per mile or km, and a chart of costs at nearby efficiency levels.

What fuel cost means

Fuel cost is the money spent on gasoline or diesel for a given distance. It excludes tolls, parking, maintenance, and time. EPA and DOE trip tools use the same core distance and efficiency idea when estimating trip fuel spending.

How to calculate fuel cost manually

1. Measure one way distance. 2. Double it for a round trip if needed. 3. Divide by MPG (or apply the metric liter formula). 4. Multiply by price. Worked example: 300 miles, 28 MPG, $3.50/gal. Gallons = 300 ÷ 28 ≈ 10.714. Cost = 10.714 × 3.50 ≈ $37.50. Cost per mile = 3.50 ÷ 28 ≈ $0.125.

Commute budgeting

Daily miles = 2 × one way. Daily cost = (daily miles ÷ MPG) × price. Weekly ≈ daily × 5. Annual ≈ daily × work days. Example: 25 mile one way, 50 miles/day, 28 MPG, $3.50. Gallons/day ≈ 1.786. Cost/day ≈ $6.25. At 240 days ≈ $1,500 per year for fuel alone.

US versus metric

US drivers usually enter miles, MPG, and dollars per gallon. Metric drivers enter kilometers, L/100km, and price per liter. Conversions use 1 mile = 1.609344 km and 1 US gallon = 3.785411784 liters. The MPG to L/100km factor 235.215 is the common planning conversion used with US gallon based MPG.

Finding your real MPG

Window sticker and fueleconomy.gov ratings are laboratory style estimates. Real MPG often runs lower with cold weather, highway speed, cargo, hills, and short trips. Track a few fill ups: miles driven ÷ gallons purchased = personal MPG.

Comparing two vehicles

Compare mode runs the same distance through vehicle A and vehicle B. Savings equal cost A minus cost B. A higher MPG car saves more gallons on long trips. The MPG illusion matters: improving from 15 to 20 MPG saves more fuel than improving from 30 to 35 MPG over the same miles.

Common mistakes

Using one way miles for a round trip budget
Mixing MPG with liters per 100 km without converting
Ignoring that city MPG and highway MPG differ
Comparing only sticker MPG when prices or fuels differ
Forgetting passengers when splitting trip cost

Practical scenarios

Road trip planners estimate tank fills. Commuters compare driving cost to transit. Families choose which car to take. Fleet managers sanity check route fuel spend. Travelers convert a metric rental car rating into trip cost at local pump prices.

When this calculator is useful

Use it for vacation routes, weekly commute budgets, vehicle choice on a shared trip, and quick cost per mile checks before you drive.

When this calculator may not be enough

It does not route maps, traffic delays, hybrid battery effects, or EV kWh pricing. For official EPA vehicle ratings and map based trips, use the DOE and EPA tools at fueleconomy.gov. For full driving cost including depreciation, check a separate cost of ownership estimate.

How to interpret your result

Hero cost is total fuel spend for the active mode. Fuel needed is gallons or liters. Per distance is cost per mile or km. Commute metrics show daily, weekly, and annual fuel spend. Compare mode reports savings versus vehicle B.

Price and efficiency sensitivity

Cost scales linearly with price and distance. Cost falls as MPG rises, but not linearly in the same way people expect. Chart bars show how nearby efficiency values change the same trip’s fuel bill.

Diesel, E85, and hybrids

Enter the pump price and efficiency that match the fuel you actually use. Hybrid EPA ratings still feed the same formula. Plug in hybrids need separate electric and gas legs if you want a blended trip cost.

City versus highway ratings

EPA labels often list city, highway, and combined MPG. Use combined for mixed routes. Prefer highway MPG for long interstate trips and city MPG for stop and go commuting so the fuel volume estimate tracks the drive you actually take.

Limitations

Estimates assume steady efficiency and a single fuel price. Real trips vary with speed, load, weather, and idling. Results are planning aids, not pump guarantees.

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Use local pump prices and your measured MPG for the most realistic budget. Sticker MPG is often optimistic in daily driving.

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DOE and EPA publish vehicle fuel economy data and a trip cost tool at fueleconomy.gov. Unit factors for the US gallon and mile follow NIST based SI conversions.

Frequently Asked Questions

How do you convert MPG to L/100km?

Divide 235.215 by MPG to get L/100km. Divide 235.215 by L/100km to get MPG. Example: 30 MPG ≈ 7.84 L/100km.

How do I estimate commute fuel cost?

Open Commute mode, enter one way distance, efficiency, price, and work days per year. The calculator doubles the one way distance for each work day, then scales to weekly and annual fuel cost.

Where do I find my car MPG?

Use the EPA window sticker, the owner manual, or fueleconomy.gov. For personal MPG, divide miles driven by gallons added across several fill ups.

Does round trip double the cost?

Yes when you return the same distance at the same efficiency and price. Check Round trip to double distance before the fuel math runs.

How accurate is the estimate?

The arithmetic is exact for the numbers you enter. Accuracy versus the pump depends on real MPG, traffic, weather, and price changes along the route.

Can I compare two cars?

Yes. Compare mode uses the same trip distance for vehicle A and vehicle B so you can see cost difference and which option saves more fuel money.

Sources & References

U.S. DOE / EPA Fuel Economy: fueleconomy.gov
DOE / EPA Fuel Economy Trip Calculator: fueleconomy.gov/trip/
NIST SI conversions (mile, US gallon to liter) used for unit consistency: NIST SP 811