Gear Ratio Calculator

Teeth/speed/torque + multi-stage

Quick Answer

Gear Ratio Calculator: Teeth/speed/torque + multi-stage. Gear Ratio Calculator uses standard science & engineering formulas to compute accurate results instantly.

Driver teeth z₁

Driven teeth z₂

Input speed n₁ (rpm)

Stage ratios (optional, comma)

Total gear ratio i

3.000 : 1

Speed reduction — output torque × 3.00 (before efficiency loss)

Single-stage i3.000

Output speed n₂483.33 rpm

Output rps8.056 r/s

Calculation steps

1Single stage i = z₂/z₁ = 60/20 = 3.000
2i > 1 = speed reduction (torque × 3.00, ignoring efficiency); i < 1 = speed increase
3Output speed n₂ = n₁ / i = 1450 / 3.000 = 483.33 rpm

Real-world ratios

Bicycle	前 42T / 后 11-34T → i = 0.32-3.8
Car 1st gear	i ≈ 3.5-4.5，低速大扭矩
Car 5th (overdrive)	i ≈ 0.7-0.8，高速省油
Gearmotor	i = 10-100 单级蜗轮/行星
Watch movement	i = 60 严格定比
Wind turbine	i ≈ 90-100（增速箱）

Power is conserved (minus efficiency): speed and torque trade off through the ratio. Typical efficiencies per stage: spur/helical gears 98-99%, worm gears 70-90% (self-locking below ~50%), belt/chain 95-98%. For multi-stage reducers multiply the ratios; for belt drives substitute pulley pitch diameters for tooth counts — i = D₂/D₁. Watch for minimum tooth count (z ≥ 17 for standard 20° gears to avoid undercutting).

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How to Use

Enter known quantities: fill values and confirm units in the Gear Ratio Calculator.
Instant solution: unknowns solve live with the formula shown transparently.
Use constant/material tables: standard physical constants and material data are listed on this page.
Compare conditions: change inputs to compare scenarios.

Key Points

Gear Ratio Calculator is a free online science & engineering tool — open and use, no sign-up.
All calculations run locally in your browser; your data never leaves the device.
Key capability: Teeth/speed/torque + multi-stage.
Results come with formulas and reference tables so you can verify every number.

Formula & How It Works

Gear Ratio Calculator formula

Gear Ratio Calculator uses standard science & engineering formulas to compute accurate results instantly.

FAQ

How do I use the Gear Ratio Calculator?

Open the page and fill in the input fields — results update automatically. Teeth/speed/torque + multi-stage.

Are the results accurate?

Yes. Standard formulas and conversion factors are used and verified.

Is it free? Do I need to sign up?

Completely free. No registration, login or download required.

Does it work on mobile?

Yes. The responsive design works on phones, tablets and desktops.

Is my data saved?

No. Everything runs locally in your browser.

Related Guides

Source & Updates

Based on CODATA recommended constants and standard physics formulas. Last updated: 2025-07

Last updated: 2026-08-05

Formulas and content on this page are reviewed by the YiJianSuan team. For reference only — official sources prevail.

Cite this page: YiJianSuan. Gear Ratio Calculator[EB/OL]. https://www.yijiansuan.com/en/c/science/gear-ratio

Results provided by this tool are for reference only and do not constitute professional advice.

Real-world ratios

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How to Use

Key Points

Formula & How It Works

FAQ

Related Tools

Related Guides

Source & Updates

Real-world ratios