Mechanical Engineering Calculators
Free machine-design calculators that show the formula and the material data. Built for machine design, not a textbook — metric and imperial, no signup.
The design tool, not a widget
Wahl-corrected stress, buckling, rod-area differentials — the depth real work needs.
Embedded material data
Pick a material or a standard size; the constants are filled in and auditable.
No black box
Every result shows its formula and the standard it follows. We don’t sell parts.
Springs
Compression spring design with material data, Wahl stress and buckling.Compression Spring Calculator
Rate, Wahl-corrected stress, solid height and buckling, with built-in material data.
Spring Rate Calculator
Spring rate (spring constant) from wire size, coil diameter and material.
Extension Spring Calculator
Rate, spring index and force at extension including initial tension.
Spring Constant Calculator
Spring constant from two measured load/deflection points (Hooke’s law).
Gears
Involute gear geometry, ratios and DXF profiles.Involute Gear Calculator
Tooth geometry from module/DP and pressure angle, with a tooth-profile render and DXF export.
Gear Ratio Calculator
Gear ratio with output RPM, torque and vehicle speed from tire size.
Gear Module Calculator
Module from pitch diameter and teeth, with diametral and circular pitch.
Gear Tooth Ratio Calculator
Single- or two-stage gear-train ratio and output speed from tooth counts.
Planetary Gear Calculator
Epicyclic gear ratio for ring-, sun- or carrier-fixed arrangements.
Worm Gear Calculator
Worm drive ratio, center distance, lead angle and self-locking check.
GD&T
True Position Calculator
GD&T true position from X/Y deviation with MMC bonus tolerance and a pass/fail check.
Flatness Tolerance Calculator
Flatness (surface form) from measured points, with a pass/fail check.
Press Fit / Interference Calculator
Interference-fit contact pressure, assembly force, torque capacity and hub stress (Lamé).
Cylindricity & Runout Calculator
Runout (TIR) and cylindricity zone from indicator and diameter readings.
Coming soon: MMC Bonus Tolerance , Composite Position Tolerance , Hole & Shaft Fit
Machining
Speeds & feeds, GD&T true position, keyways and press fits.Surface Feet per Minute Calculator
Cutting speed (SFM / m·min) and diameter to spindle RPM, with cutting speeds by material.
Bore & Stroke Calculator
Engine displacement (cc / L / ci) and bore/stroke ratio from bore, stroke and cylinders.
Tap Drill Size Calculator
Tap drill diameter for any metric or unified thread at your chosen % thread engagement.
Keyway Dimension Calculator
Standard parallel key & keyway dimensions for a shaft per DIN 6885-1.
Hydraulics
Cylinder force and fluid-power math.Coming soon: Hydraulic Pump Flow & HP , Pneumatic Air Consumption
Power Transmission
Pulleys, sprockets and belts — ratios, speed and length.Pulley Calculator
Pulley ratio, driven RPM and belt speed from pulley diameters.
Sprocket Calculator
Sprocket ratio, RPM, chain speed and pitch diameters for a chain drive.
Belt Length Calculator
Two-pulley belt length and wrap angle from center distance and diameters.
Coming soon: Chain Length , Bearing Life (L10)
Fasteners
Bolt Preload & Torque Calculator
Clamp force (preload) from tightening torque and the nut factor.
Bolt Circle Coordinate Calculator
X-Y hole coordinates and spacing on a bolt circle, with a layout render.
Fillet Weld Size Calculator
Effective throat and weld capacity from leg size, length and electrode (AWS/AISC).
Sheet Metal
Guides
The formulas and standards behind the tools, explained.
27 calculators live and growing · About & methodology