Mechanical Engineering Calculators

Calculators for mechanical and manufacturing work: power transmission, fastener torque, belt drives and threading. Each tool documents the formula and the friction or material factors it assumes.

• Gear Ratio CalculatorCalculate gear ratio from teeth counts, with output RPM and torque including mesh efficiency. Supports single-stage and explained multi-stage use.
• Torque to Power CalculatorConvert torque and RPM to mechanical power in kW, hp and lb·ft. Includes the exact formulas and the difference between shaft, brake and rated power.
• Bolt Torque CalculatorCalculate tightening torque for metric bolts by grade and size, with preload at 75% of proof load and dry or lubricated friction. Includes the K-factor model.
• Belt Length CalculatorCalculate open-belt length from two pulley diameters and center distance, with speed ratio. Classical V-belt/flat-belt geometry, metric and imperial output.
• Tap Drill CalculatorCalculate tap drill size for metric threads at any thread engagement percentage, with the standard 75% recommendation and nearest drill bit size.
• Pulley RPM CalculatorCalculate driven pulley RPM from diameters and driver speed, with belt speed check. For V-belt and flat-belt drives using pitch diameters.
• Hydraulic Cylinder CalculatorCalculate hydraulic cylinder force from bore, rod and pressure, for both extend and retract strokes. kN and lbf, with the annulus area explained.
• Gear Geometry CalculatorCalculate spur gear geometry from module and tooth count: pitch, outside and root diameters, circular pitch and tooth depth. ISO module system.
• Metal Weight CalculatorCalculate the weight of steel, aluminum, stainless, brass and other metals in round bar, square bar, plate and tube shapes. kg and lb.
• Engine Displacement CalculatorCalculate engine displacement in cc, liters and cubic inches from bore, stroke and cylinder count. Per-cylinder volume included.
• Compression Ratio CalculatorCalculate static compression ratio from swept volume, chamber volume, gasket volume and piston dome/dish. Essential engine building math.
• Spring Rate CalculatorCalculate compression spring rate from wire diameter, coil diameter and active coils. N/mm and lbf/in, with spring index guidance.
• Torque Wrench Extension CalculatorCorrect torque wrench settings when using extensions or crowfoot wrenches in line with the handle. Get the reduced setting that hits the target.
• Pump Power CalculatorCalculate pump hydraulic and shaft power from flow, head and efficiency. Water horsepower, brake horsepower and motor sizing in kW and hp.
• Chain Length CalculatorCalculate roller chain length from sprocket teeth and center distance, in pitches, links, mm and inches. Recommends even link counts.
• Bearing Life CalculatorCalculate ball or roller bearing L10 life from dynamic load rating, applied load and speed. Hours, revolutions and years at the duty point.