Everyday calculator
Fuel Cost Calculator, Trip Cost by Distance, MPG & Gas Price
Estimate fuel costs for any trip based on distance, fuel efficiency, and gas price. Compare cost per mile and total round-trip expenses.
How CalcMesh estimates fuel cost
Trip fuel cost equals distance divided by fuel economy, multiplied by the price per unit of fuel. For example, a 300-mile trip at 30 miles per gallon and $3.50 per gallon costs $35.00.
We compute total and per-mile cost from your inputs; real consumption varies with speed, load and terrain, which we discuss in our methodology.
Tips to Improve Fuel Efficiency
- Maintain tire pressure: Under-inflated tires increase rolling resistance and can reduce efficiency by 3% or more.
- Drive smoothly: Avoid rapid acceleration and hard braking. Aggressive driving can lower MPG by 15-30% on highways.
- Optimal speed: Most cars are most efficient at 45-65 mph. Every 5 mph over 50 mph is roughly like paying an extra $0.30 per gallon.
- Reduce idling: Idling uses a quarter to a half gallon per hour. Turn off the engine if you'll be stopped for more than a minute.
- Regular maintenance: Clean air filters, fresh oil, and proper tune-ups help your engine run efficiently.
- Lighten the load: Every 100 lbs of extra weight reduces MPG by about 1%.
MPG vs L/100km
The US uses Miles Per Gallon (MPG) where higher is better. Most of the world uses Liters per 100 Kilometers (L/100km) where lower is better. The conversion formula is: L/100km = 235.215 / MPG.
| MPG | L/100km |
|---|---|
| 20 MPG | 11.8 L/100km |
| 30 MPG | 7.8 L/100km |
| 40 MPG | 5.9 L/100km |
| 50 MPG | 4.7 L/100km |
When to Use This Calculator
- Road trip planning: Budget total fuel costs before a long drive across multiple states.
- Vehicle comparison: See annual fuel cost difference between a 22 MPG SUV vs 35 MPG sedan at 15,000 miles/year.
- Commute costs: Calculate monthly fuel expense for a daily work commute to factor into budgeting.
Real-World Examples
Example 1, Road trip: 1,200-mile round trip, 28 MPG vehicle, $3.50/gallon. Fuel needed: 42.9 gallons. Total cost: $150. Cost per mile: $0.125.
Example 2, Annual commute: 30 miles/day, 250 days/year = 7,500 miles. At 22 MPG and $3.50/gallon: $1,193/year. Switching to a 35 MPG hybrid saves $455/year.
Limitations & Assumptions
- Uses a single MPG figure, actual efficiency varies between city and highway driving.
- Gas price is entered manually, check current local prices at GasBuddy or AAA.
- Does not account for tolls, EV charging costs, or hybrid electric-mode miles.
Data Sources
MPG/L/100km conversion formula: 235.215 (derived from unit analysis). Fuel efficiency guidance from US Department of Energy fueleconomy.gov and EPA test cycle data. Speed-efficiency curve per DOE Oak Ridge National Laboratory vehicle analysis.
Note: Actual fuel costs depend on driving conditions, vehicle maintenance, and real-time fuel prices. This calculator provides estimates only.
Methodology & Assumptions
This calculator implements standard formulas drawn from primary-source authorities. Values are point-in-time estimates; consult a licensed professional for high-stakes decisions. See the per-input definitions and source citations below.
How this works
Computations are deterministic and run client-side, no inputs leave your
browser. Formulas are derived from
standard published formulas for the calculator's domain (mortgage,
taxes, energy, conversions, etc.). When the underlying agency publishes
updated rates or thresholds we refresh defaults and update the page's
lastmod timestamp.
| Input | Default | Source / authority |
|---|---|---|
| All inputs | Domain-typical defaults | Editorial methodology, CalcMesh 2026 |