Free Automotive Calculators

Compare two tire sizes side by side. See diameter difference, width change, sidewall height, circumference, revs per mile, and speedometer error.

Calculate actual speed vs displayed speed after changing tire sizes. See error at every speed from 30 to 80 mph.

Find the correct tire pressure adjusted for temperature changes and load level. See how weather affects your PSI and TPMS threshold.

Calculate your vehicle's miles per gallon from miles driven and gallons used. Includes cost per mile and L/100km conversion.

Estimate fuel cost for any trip. Enter distance, vehicle MPG, and gas price. Includes round-trip toggle and MPG comparison table.

Calculate road trip fuel cost, split between passengers, and estimate drive time. Includes round-trip toggle and cost-per-mile breakdown.

Calculate remaining payload and max trailer weight. Includes tongue weight check and safety indicators.

Calculate the correct tongue weight for your trailer using the 10-15% rule. Check if your actual tongue weight is safe and within hitch limits.

Calculate axle gear ratio from ring and pinion teeth. See RPM at any speed, effective ratio with tire size, and compare common ratios.

Calculate engine displacement from bore, stroke, and cylinder count. Results in cubic inches, liters, and cc with bore/stroke analysis.

Estimate engine horsepower from quarter mile time, trap speed, or dyno wheel HP. Includes drivetrain loss calculator and HP tables.

Estimate real-world EV range adjusted for temperature, driving style, and efficiency. Includes charging cost and range comparison for 10 popular EVs.

Calculate EV charging cost and time for Level 1, Level 2, and DC fast charging. Compare home vs public charging costs.

Calculate how much coolant and water to drain and add for any mix ratio. Includes freeze/boil protection chart and coolant type guide.

Find oil capacity by vehicle type, track oil change intervals, and calculate DIY oil change cost. Includes oil life tracker.

Estimate brake pad lifespan from driving style, road conditions, and annual mileage. Includes replacement cost and wear tracker.

Estimate car battery lifespan based on climate, driving patterns, and electrical load. Track battery age and plan replacement.

Find the correct wiper blade size for your vehicle type. Compare conventional, beam, hybrid, and silicone wipers with price data.

Compare annual car wash costs: home wash vs automatic vs unlimited subscription vs professional detailing. Find the best value.

Estimate automotive paint and body work costs by job type, vehicle size, and extras like rust or dent repair.