Gear Ratio & RPM Calculator
Calculate driver/driven gear ratio, output RPM, and torque multiplier.
Last reviewed by the myCalculator Editorial Team
Input Parameters
Calculation Results
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Formula & How Gear Ratio & RPM Calculator Works
The gear ratio is the number of teeth on the driven gear divided by the teeth on the driving gear. A 12-tooth driver turning a 36-tooth driven gear gives a ratio of 3:1. The driven gear turns at one-third of the speed and delivers three times the torque, less friction losses. In a compound train you multiply the ratios of each stage. Cyclists use the ratio to choose gears, and engineers use it to match a motor's speed to a load. Higher ratios give more torque and less speed, while lower ratios give more speed and less torque. Efficiency is typically 90% or higher for a good gear mesh, so allow for a small loss.
- Enter Driver Gear Teeth (Input): Input your target parameter value.
- Enter Driven Gear Teeth (Output): Input your target parameter value.
- Enter Input Motor Speed (RPM): Input your target parameter value.
- Apply Formula: Calculate using
Gear Ratio = Teeth (Driven) / Teeth (Driver). - Review Results: View exact computed answers, metrics, and worked mathematical proofs.
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Are you using our calculation results for a university assignment, research paper, or academic report? Use the auto-generated citations below to accurately reference this tool in your bibliography.
MyCalculator.com.au. (2026). Gear Ratio & RPM Calculator. Retrieved October 24, 2026, from https://www.mycalculator.com.au/calculators/engineering/gear-ratio
MyCalculator.com.au. (2026) 'Gear Ratio & RPM Calculator'. Available at: https://www.mycalculator.com.au/calculators/engineering/gear-ratio (Accessed: 24 October 2026).
Frequently Asked Questions (FAQs)
What is mechanical advantage in gear systems?
The factor by which a gear system multiplies output torque relative to input.
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Authoritative Standards & Verified Reference Citations
Calculations and mathematical logic on this page are grounded in published statutory rules, regulatory standards, and official government data published by the following bodies:
Australian Standards including AS/NZS 3000 (Wiring Rules), AS 3600 (Concrete Structures), and AS 4100 (Steel Structures).
Accreditation and technical guidelines for civil, structural, mechanical, and electrical engineering.
Dedicated Australian home loans, borrowing capacity, mortgage repayments & refinance modeling.