Automotive tools & calculators

Free calculators for car owners, mechanics and technicians. Everything runs in your browser.

Wheels & tires

Tire Size CalculatorCompare two tire sizes: diameter, sidewall, circumference and speedometer error.Tire Pressure ConverterConvert tire pressure between PSI, bar, kPa and kgf/cm², with cold vs hot guidance.Wheel Offset & Fitment CalculatorSee how a new wheel's width and offset (ET) change inner clearance and outer poke.

Running costs

Fuel Consumption CalculatorConvert MPG and L/100km, and work out trip and yearly fuel costs.Vehicle ComparisonCompare engines, fuel economy and CO2 of any two vehicles from the EPA database.Car Depreciation CalculatorEstimate a car's value over time and the cost of depreciation per year.

Diagnostics

VIN DecoderDecode a 17-character VIN: manufacturer, model year, check digit and NHTSA data.

Engine

Horsepower & Torque Converterhp, kW and PS; Nm and lb-ft; power from torque and RPM; power-to-weight.Engine Displacement CalculatorEngine size from bore, stroke and cylinders, plus compression ratio.

Drivetrain

Gear Ratio & Speed CalculatorVehicle speed at any RPM in every gear, from gear ratios, final drive and tire size.

Fluids

Coolant Mix CalculatorHow much coolant to drain and replace with concentrate to reach a target mix.

Workshop

Torque Unit ConverterConvert Nm, lb-ft, lb-in and kgf·m for torque wrench settings.

Electrical

Automotive Electrical & Wire Gauge CalculatorOhm's law, watts to amps, wire size by voltage drop and fuse size estimates.EV Charging Time & Cost CalculatorHow long an electric car takes to charge on AC or DC, and what it costs.Car Battery Runtime & Charging CalculatorHow long a battery runs a load, and how long it takes to recharge.

Maintenance

Car Maintenance Schedule CalculatorSee which service items are due or overdue from your odometer and last service.

Towing

Towing & Payload CalculatorCheck tongue weight, payload, combined weight and towing capacity against your vehicle's limits.

Diagnostics databases

OBD2 Code LookupMeaning, causes and diagnosis for generic trouble codes.Warning Light LookupWhat dashboard warning lights mean and what to do.Tire Size ChartDimensions and equivalent sizes for common tires.