Use this engineering calculation for a transparent preliminary estimate or independent arithmetic check when geometry, materials, loads, operating conditions, and units are defined consistently.

Driver Teeth

Required integer input.

Driven Teeth

Required integer input.

Ideal simple external-gear speed reduction ratio from driven and driver tooth counts; excludes idlers and losses. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Reduction Ratio

The resulting reduction ratio returned as a number.

• Gear ratios describe ideal kinematics. Tooth counts, module, pressure angle, center distance, backlash, undercut, strength, efficiency, lubrication, alignment, dynamics, and service factor determine a workable transmission.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check assumptions against drawings, measurements, current material data, and the applicable design code. Apply required load combinations and safety factors, then obtain qualified review and testing for consequential designs.

• Chain Drive Speed Ratio

  Ideal driven-to-driver chain sprocket speed ratio from integer tooth counts.

• Belt Drive Speed Ratio

  Ideal no-slip driven-to-driver pulley speed ratio from pitch diameters.

• Worm Gear Ratio

  Ideal worm gear reduction ratio from wheel tooth count divided by worm starts.