Cog Gear Calc

Calculate gear ratios instantly. Built for engineers, hobbyists, and mechanics — offline, no ads.

Cog is a fast, offline gear ratio calculator and reference tool for engineers, hobbyists, and mechanics.

Enter the driving and driven tooth counts plus your input RPM — Cog instantly computes the gear ratio, output RPM, and mechanical advantage with live recomputation as you type.

The Gears tab gives you a catalog of 24 real-world gear specifications across five gear types: spur, helical, bevel, planetary, and worm — each with tooth count and a plain-English use case description. Filter by type or search by name.

Save your most-used gear configurations in Setups. Name them, add notes, and recall the full ratio calculation at any time. Six example setups are included: bike gears, industrial reducers, worm drives, clock escapements, and more.

Everything works offline. No account, no ads, no tracking.

Features:

• Live gear ratio, output RPM, and mechanical advantage from driving/driven teeth + input RPM
• Speed reduction vs. speed increase summary with directional torque note
• 24-gear reference catalog: spur, helical, bevel, planetary, worm
• Filter and search the gear catalog by type or keyword
• Save named setups with notes for quick recall
• Full offline — no internet connection required