Calculate how much fuel you need and what a trip will cost based on distance, fuel efficiency, and gas price.
US formula: Fuel needed = Distance / MPG. Cost = Fuel needed x Price per gallon.
Metric formula: Fuel needed = (Distance / 100) x L/100km. Cost = Fuel needed x Price per liter.
Example: A 300-mile trip at 25 MPG with gas at $3.50/gallon: 300/25 = 12 gallons needed. 12 x $3.50 = $42.00 total fuel cost.
Fuel costs are often the single largest variable expense when driving, whether for daily commuting or long road trips. The three factors that determine your fuel cost are distance, fuel efficiency, and the price of fuel. Understanding how these three interact helps you budget for trips, compare vehicles, evaluate whether driving is cheaper than flying, and make informed decisions about your transportation choices.
Fuel efficiency (measured in miles per gallon in the US or liters per 100 kilometers in most other countries) varies dramatically between vehicles. A compact sedan might achieve 35 MPG on the highway while a large SUV gets only 18 MPG. This means the SUV costs nearly double the fuel for the same trip. Over the course of a year, a driver covering 15,000 miles spends about $1,500 at 35 MPG versus $2,917 at 18 MPG (at $3.50/gallon) -- a difference of $1,417 annually just in fuel.
Gas prices fluctuate based on crude oil markets, refining costs, distribution expenses, and local taxes. State gas taxes in the US range from about 9 cents per gallon in Alaska to over 60 cents in California and Pennsylvania. International prices vary even more: gas costs roughly $6-8 per gallon in much of Europe due to higher taxes, while some oil-producing nations subsidize fuel to keep prices below $1 per gallon. These variations make fuel cost calculators essential for trip planning and budgeting.
| Vehicle Type | Average MPG | L/100km | Cost per 100 mi* |
|---|---|---|---|
| Compact car | 33 | 7.1 | $10.61 |
| Midsize sedan | 28 | 8.4 | $12.50 |
| SUV | 22 | 10.7 | $15.91 |
| Pickup truck | 18 | 13.1 | $19.44 |
| Hybrid | 48 | 4.9 | $7.29 |
| Motorcycle | 55 | 4.3 | $6.36 |
*At $3.50 per gallon
Maintain proper tire pressure. Under-inflated tires increase rolling resistance, reducing fuel efficiency by up to 3%. Check your tire pressure monthly and inflate to the manufacturer's recommended PSI (found on a sticker inside the driver's door jamb). Properly inflated tires also last longer and handle better.
Drive at moderate speeds. Fuel efficiency drops significantly above 50 mph. Each 5 mph over 50 is roughly equivalent to paying an extra $0.20 per gallon. Use cruise control on highways to maintain a steady speed and avoid the fuel waste of constant acceleration and braking.
Reduce excess weight and drag. Every 100 pounds of extra weight reduces fuel efficiency by about 1%. Remove roof racks when not in use -- they create aerodynamic drag that can reduce highway fuel efficiency by up to 25%. Keep your trunk clean of unnecessary heavy items.
Plan routes efficiently. Use GPS apps that optimize for the shortest or most fuel-efficient route. Combine errands into a single trip to avoid multiple cold starts, which use more fuel. A warm engine is more fuel-efficient than a cold one, so grouping trips together saves gas even if the total distance is the same.
Divide the total miles by your car's MPG to get gallons needed, then multiply by the price per gallon. For example, 500 miles at 30 MPG with $3.50 gas: 500/30 = 16.67 gallons x $3.50 = $58.33.
The average new car in the US gets about 28 MPG combined. Above 30 MPG is considered good, above 40 MPG is excellent. Hybrids typically achieve 45-55 MPG, and plug-in hybrids can exceed 100 MPGe.
Divide 235.215 by the MPG value. For example, 30 MPG = 235.215/30 = 7.84 L/100km. Conversely, divide 235.215 by L/100km to get MPG.
Yes. Aerodynamic drag increases with the square of speed, so doubling your speed quadruples the drag. Most vehicles are most fuel-efficient between 35-55 mph. Driving 70 mph instead of 55 mph can reduce fuel efficiency by 15-25%.
Generally, driving is cheaper for trips under 300 miles, especially with multiple passengers splitting the fuel cost. For trips over 500 miles, flying is usually faster and often comparable in cost for solo travelers. Between 300-500 miles, it depends on gas prices, vehicle efficiency, and airfare prices.