Automotive Calculators — Engine, Fuel, Tires, EV & Loan Tools
55+ free automotive calculators covering engine performance, fuel economy, wheels & tires, electric vehicles, and vehicle financing. From estimating horsepower and quarter-mile times to comparing tire sizes and calculating loan payments — instant, accurate results for every automotive need.
Calculator Categories
Engine & Performance (10)
Horsepower, torque, displacement, compression ratio, carburetor CFM, quarter mile, gear ratio & more.
Fuel Economy (9)
Gas mileage (MPG), fuel cost, fuel savings, cost per mile, MPG ↔ L/100km converter & more.
Wheels & Tires (8)
Tire size calculator, tire comparison, speedometer error, wheel offset, bolt pattern & more.
EV Calculators (22)
EV vs gas comparison, charging cost & time, range estimator, tax credit eligibility, battery degradation & more.
Vehicle Loan Calculators (7)
Auto loan, car lease, lease vs buy, motorcycle, boat, RV, and ATV loan payment calculators.
🔧 Engine & Performance Calculators
Engine Horsepower Calculator
Calculate engine horsepower using RPM & torque, quarter-mile elapsed time, or trap speed methods. Supports HP, kW, and PS conversions.
★★★★★Engine Torque Calculator
Calculate engine torque from horsepower and RPM. Convert between lb-ft, Nm, and kg-m. See the torque curve relationship.
★★★★★Engine Displacement Calculator
Calculate engine displacement (CID/cc/L) from bore, stroke, and number of cylinders. Compare common engine configurations.
★★★★☆Engine Compression Ratio Calculator
Calculate engine compression ratio from swept volume and clearance volume. Understand the impact on power and fuel octane requirements.
★★★★☆Carburetor CFM Calculator
Calculate the correct carburetor size in CFM for your engine using displacement, RPM, and volumetric efficiency.
★★★★☆0–60 & Quarter Mile Calculator
Estimate quarter-mile elapsed time and trap speed from vehicle weight and horsepower. Calculate 0-60 mph time.
★★★★★Horsepower-to-Weight Ratio Calculator
Calculate power-to-weight ratio in HP/ton, lb/HP, and HP/liter. Compare your vehicle's performance potential against common benchmarks.
★★★★☆Gear Ratio Calculator
Calculate overall gear ratio, RPM at speed, and speed at RPM from transmission gear, differential ratio, and tire size.
★★★★☆Top Speed Estimator
Estimate a vehicle's theoretical top speed from horsepower, weight, drag coefficient, and frontal area.
★★★★☆Dyno Correction Factor Calculator
Calculate SAE J1349, DIN 70020, and STD dyno correction factors from temperature, barometric pressure, and humidity.
★★★★☆⛽ Fuel Economy Calculators
Gas Mileage Calculator
Calculate your vehicle's gas mileage (MPG) from distance traveled and fuel used. See cost per mile and metric equivalents.
★★★★★Fuel Cost Calculator
Calculate the fuel cost for any trip distance based on your vehicle's MPG and current gas price. Compare regular, mid-grade, and premium.
★★★★★Fuel Savings Calculator
Compare annual fuel costs between two vehicles. See how much you'd save by switching to a more fuel-efficient car.
★★★★★Cost Per Mile Calculator
Calculate the true all-in cost per mile including fuel, insurance, maintenance, depreciation, and financing.
★★★★★Fuel Injector Flow Rate Calculator
Calculate required fuel injector flow rate (lb/hr or cc/min) based on target horsepower, BSFC, number of injectors, and duty cycle.
★★★★☆Fuel Tank Range Calculator
Calculate how far you can drive on a full tank or remaining fuel based on your vehicle's MPG and tank size.
★★★★☆Annual Fuel Cost Calculator
Calculate your total annual fuel expenditure based on yearly miles driven, vehicle MPG, and local fuel price.
★★★★☆MPG Improvement Savings Calculator
Calculate how much money you save by improving your vehicle's fuel economy from one MPG to another over a year.
★★★★☆🛞 Wheels & Tires Calculators
Tire Size Calculator
Decode any tire size (P-metric, LT-metric, flotation) into actual dimensions — diameter, width, sidewall height, circumference, and revolutions per mile.
★★★★★Tire Size Comparison Calculator
Compare two tire sizes side by side — diameter difference, width difference, speedometer error, and fitment compatibility.
★★★★★Tire Size Conversion Calculator
Convert tire sizes between P-metric (225/55R17), inches (28×10.50R15), and metric (750-16) formats.
★★★★☆Speedometer Error Calculator
Calculate speedometer error caused by changing tire sizes. See your actual speed vs. displayed speed at any indicated speed.
★★★★★Speedometer Gear Calculator
Calculate the correct speedometer driven gear tooth count for mechanical speedometers after changing tire size or axle ratio.
★★★★☆Wheel Offset Calculator
Calculate wheel offset (ET), backspacing, and track width change when switching to different wheels. Ensure safe fender clearance.
★★★★★Tire Pressure Adjustment Calculator
Calculate the correct tire pressure adjustment for temperature changes, load variations, and altitude. PSI and bar units supported.
★★★★☆Bolt Pattern / PCD Calculator
Calculate Pitch Circle Diameter (PCD) from number of bolts and measurement between them. Find compatible wheel bolt patterns.
★★★★☆💡 Why Use Our Automotive Calculators?
Whether you're building a high-performance engine, shopping for the right tires, planning a road trip on a budget, or financing your next vehicle — these automotive calculators give you the precise numbers you need. Every tool provides instant results with both US and metric units displayed inline, so you never have to convert manually.
Our engine calculators use industry-standard formulas (SAE J1349, Roger Huntington's ¼-mile method) and include preset data for popular engines. Fuel economy tools compare costs across vehicles and project multi-year savings. Tire calculators decode P-metric notation, flag speedometer errors, and verify fitment safety — all in real time as you type.
Automotive Calculator FAQ
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