Fuel Cost Calculator

About the Fuel Cost Calculator

A fuel cost calculator estimates the total fuel expense for any trip based on distance, vehicle fuel efficiency, and current fuel price — and can compare running costs between any two vehicles to show which is cheaper to operate over any given period. Whether you are planning a road trip and want to budget for petrol, comparing the annual fuel cost of two vehicles before a purchase, calculating commute costs for a car allowance, or evaluating the economics of a fuel-efficient vehicle upgrade, this tool gives you precise, accurate cost estimates. It works with both imperial inputs (miles per gallon, price per gallon in USD or GBP) and metric inputs (litres per 100 km, price per litre in CAD, AUD, or EUR) and includes an annual cost projection based on your typical weekly mileage. The calculator is used by millions of drivers across the USA, UK, Canada, and Australia every time fuel prices fluctuate and driving economics need reassessment.

How It Works

Fuel cost formula (MPG): Cost = (Distance / MPG) x Price per gallon. Example: 450-mile road trip, 32 MPG vehicle, $3.45/gallon: Fuel cost = (450 / 32) x $3.45 = 14.06 gallons x $3.45 = $48.52. Metric formula (L/100km): Cost = (Distance / 100) x Fuel consumption (L/100km) x Price per litre. Example: 700 km trip, 7.5 L/100km, $1.65/L: Cost = (700/100) x 7.5 x $1.65 = 7 x 7.5 x $1.65 = $86.63. Annual fuel cost: Cost per km x annual kilometres. Vehicle comparison: annual savings from upgrading from 25 MPG to 38 MPG for a 15,000-mile/year driver at $3.50/gallon = (15,000/25 - 15,000/38) x $3.50 = (600 - 394.7) x $3.50 = 205.3 gallons x $3.50 = $718.55 saved per year.

Tips & Best Practices

• ✓Tyre pressure: every 1 PSI below the recommended pressure reduces fuel economy by approximately 0.2%. Monthly tyre pressure checks are one of the lowest-effort ways to maintain optimal fuel economy.
• ✓Speed versus fuel economy: most petrol vehicles achieve peak fuel efficiency around 50-55 mph. Above 65 mph, aerodynamic drag increases significantly — driving 75 mph instead of 65 mph typically reduces fuel economy by 10-15%.
• ✓Air conditioning impact: AC increases fuel consumption by 5-25% depending on ambient temperature and vehicle size. On short city trips in hot weather, opening windows below 45 mph is more efficient; at highway speeds, AC is more efficient than the aerodynamic drag of open windows.
• ✓Cold weather effect: fuel economy drops 15-25% in cold weather (below 20°F) primarily due to engine warm-up time, increased idling, and higher rolling resistance from cold tyres and lubricants.
• ✓Hypermiling techniques: smooth acceleration and braking, anticipating traffic flow, coasting to stops, and maintaining highway speeds with cruise control can improve real-world fuel economy by 10-20% versus aggressive driving.
• ✓Ethanol blends: E10 (10% ethanol) reduces fuel economy by approximately 3-4% compared to pure petrol because ethanol has lower energy density. E85 (85% ethanol) reduces economy by 25-30%.
• ✓Roof racks and cargo carriers: an empty roof rack adds 2-8% drag penalty; a loaded cargo box adds 10-25% depending on size and vehicle. Remove roof accessories when not in use.
• ✓Regular maintenance: a tuned engine (clean air filter, fresh spark plugs, correct oil viscosity) runs at optimal efficiency. A clogged air filter alone can reduce fuel economy by up to 10%.

Who Uses This Calculator

Road trip planners budgeting petrol expenses before departure. Commuters calculating monthly fuel costs to compare against public transport alternatives. Fleet managers estimating vehicle operating expenses for budget planning. Car buyers comparing total-cost-of-ownership between efficient and less efficient vehicles. Tax filers calculating vehicle expense deductions based on actual fuel costs versus the standard mileage rate.