GearTeeth · mechanical

GearTeeth gear tooth ratio

Predict output shaft speed after a spur-gear tooth ratio change

TECHNICAL UTILITY · GEAR_TOOTH_RATIO

Result

Enter values to begin.

ratio=driven_teeth/driver_teeth; driven_rpm=driver_rpm·driver_teeth/driven_teeth

How to use this estimate

Compute gear ratio and driven RPM from tooth counts and driver RPM. How it works: ratio=driven_teeth/driver_teeth; driven_rpm=driver_rpm·driver_teeth/driven_teeth. Out of scope: belt/pulley diameter ratio; planetary compounds; tooth strength / AGMA rating; backlash. This is an approximate screening estimate, not a substitute for manufacturer charts or a full engineering design. Does not certify code compliance; confirm manufacturer data where it applies.

Sources, methodology, and assumptions

Methodology

ratio=driven_teeth/driver_teeth; driven_rpm=driver_rpm·driver_teeth/driven_teeth

Assumptions

External spur mesh; Integer tooth counts; No slip. This is an approximate screening estimate, not a substitute for manufacturer charts or a full engineering design.

Out of scope

belt/pulley diameter ratio; planetary compounds; tooth strength / AGMA rating; backlash

Sources

NIST SP 811 — unit consistency context (not exact formula page) — NIST
NIST dimensional / kinematics unit context — NIST

Last technically reviewed: 2026-09-11