Our Automotive Calculators help drivers, enthusiasts, mechanics, engineers, and vehicle owners quickly calculate fuel costs, mileage, electric vehicle running costs, tyre fitment, gear ratios, engine performance, and power or torque conversions. Whether you're planning a road trip, comparing vehicle specifications, upgrading wheels, or tuning a performance car, our free online automotive tools provide fast, accurate, and easy-to-understand results.
Estimate fuel costs for any journey using distance, fuel efficiency and fuel prices.
Estimate fuel costs and HMRC mileage claims for business and personal journeys.
Compare fuel and electricity costs to see how much you could save by driving an electric vehicle.
Calculate HP per tonne and kW per tonne to compare the performance of cars, motorcycles, and electric vehicles.
Convert instantly between Horsepower (HP), Metric Horsepower (PS), and Kilowatts (kW).
Convert torque between Newton metres (Nm), pound-feet (lb-ft), pound-inches (lb-in), and kilogram-metres (kg·m).
Compare tyre sizes, rolling diameter, sidewall height, circumference, and speedometer difference.
Compare wheel width, offset (ET), and tyre fitment to see inner and outer clearance changes.
Calculate gear ratios, final drive ratios, wheel speed, and torque multiplication for any drivetrain.
Automotive calculators simplify many common vehicle-related calculations that would otherwise require complex formulas, conversion tables, or specialist software. They help estimate running costs, compare vehicle performance, analyse drivetrain specifications, calculate wheel fitment, and convert engineering units used throughout the automotive industry.
Our calculators support the most common measurement systems used across the United Kingdom, Europe, North America, Australia, and international motorsport.
Our automotive calculators are useful for a wide variety of everyday driving, maintenance and performance tasks, including:
Modern vehicles use many different measurement systems depending on the manufacturer and country. Engine power may be quoted in HP, PS, or kW, while torque may appear in Nm or lb-ft. Tyres, wheels and drivetrain components also require careful calculations to ensure compatibility and performance.
Our calculators remove the guesswork by performing accurate calculations instantly, helping you make informed decisions whether you're maintaining a family car, modifying a performance vehicle or comparing electric and petrol running costs.
A 250-mile journey in a car averaging 45 MPG with petrol costing £1.45 per litre.
A performance car produces 650 PS.
Vehicle Power: 500 HP
Vehicle Weight: 1,600 kg
Can I use these calculators for motorcycles?
Yes. Most calculators work equally well for motorcycles, cars, vans, trucks and electric vehicles.
Why do European manufacturers use PS instead of HP?
PS (Pferdestärke) is the traditional metric horsepower used throughout much of Europe and remains common in manufacturer specifications.
Will changing tyre size affect my speedometer?
Yes. Larger or smaller tyre diameters can change your speedometer reading and gearing. Our Tyre Size Calculator helps estimate the difference before changing tyres.
Can I compare EV and petrol running costs?
Yes. Our EV vs Petrol Running Cost Calculator estimates the difference in energy costs based on your mileage and local electricity and fuel prices.
Why use a Wheel Offset Calculator?
Changing wheel width or offset affects suspension clearance, brake clearance and how far the wheel sits inside or outside the wheel arch. Calculating these changes before purchasing new wheels helps avoid expensive mistakes.
Simple Calculator is an independent family-run project focused on creating practical online tools that are fast, accurate and easy to use. Every automotive calculator is built using recognised engineering formulas and industry-standard conversion factors, with responsive designs that work perfectly on desktop, tablet and mobile devices.
You may also find our Financial Calculators, Unit Converters, Scientific Calculators, and Everyday Calculators useful.
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Last Updated: August 2026