Car Calculators & Converters

Convert power figures between kilowatts, mechanical horsepower (BHP/HP) and metric horsepower (PS) in either direction.

Convert torque figures between newton-metres (Nm) and pound-feet (lb-ft) in either direction.

Work out a car’s power-to-weight ratio in BHP per tonne, with kW per tonne shown alongside, and compare two cars side by side.

Work out total engine displacement in cc, litres and cubic inches from bore, stroke and cylinder count, with an optional comparison setup.

Compare the cost of a modification against the power it gains — total cost, BHP gained, percentage increase and cost per BHP, with up to three options side by side.

Compare an original and proposed tyre size side by side — sidewall, diameter, circumference, ride-height change and speedometer effect, with a scaled diagram.

Compare original and proposed wheel widths, offsets and spacers to see how far the wheel moves outward and how inner clearance changes.

Estimate road speed from engine RPM — or engine RPM from road speed — using tyre size, gear ratio and final drive, with an optional multi-gear comparison table.

Convert pressure between bar, PSI and kPa in either direction — handy for tyre pressures and turbo boost readings.

Convert between UK MPG, US MPG and L/100 km, or work out your real-world fuel economy from distance and fuel used.

Estimate the fuel cost of a journey from distance, fuel economy and fuel price, with a return-trip option and per-person cost splitting.

Compare the estimated annual fuel costs of two cars (with an optional third) from your annual mileage, each car’s economy and fuel price, with a clear bar chart.

Plan a complete track-day budget with an itemised breakdown, contingency, and per-session and per-track-minute costs — with direct or calculated fuel.