By Zencalcy Editorial TeamLast reviewed About us
Work out the gear ratio your drivetrain gives you by dividing the chainring teeth by the cassette cog teeth. A higher ratio means a bigger, harder gear, while a lower ratio means an easier gear for climbing. The result also shows what the ratio means as metres of development.
Find the ratio between your chainring and cassette teeth.
gear ratio = chainring teeth ÷ cassette cog teeth
The development note uses a 700c wheel with a rolling circumference of about 2.105 m, so metres of development = ratio × 2.105. A different tyre or wheel size shifts that figure.
| Symbol | Meaning |
|---|---|
| chainring | Teeth on the front chainring currently in use. |
| cog | Teeth on the rear cassette cog currently in use. |
A 50 tooth chainring with an 11 tooth cog gives 50 ÷ 11 = 4.55, a big gear for fast flat riding. The same chainring with a 28 tooth cog gives 50 ÷ 28 = 1.79, a much easier gear for climbing.
Gear ratio is the number of teeth on the front chainring divided by the number of teeth on the rear cog, so a fifty tooth chainring paired with a fifteen tooth cog gives a ratio of about 3.33. That number is the count of rear wheel revolutions produced by one full turn of the pedals, which makes it the simplest way to describe how hard a gear is.
Multiplying the ratio by the wheel circumference gives development, the actual distance the bike moves per pedal revolution. A road wheel with its tyre often measures close to 2.1 metres around, so a ratio of 3.33 develops roughly seven metres each crank turn. Development is more useful than a bare ratio because two bicycles with identical ratios but different wheel sizes travel different distances.
A larger chainring or a smaller rear cog raises the ratio and makes the gear harder to push but faster at any given cadence. Shifting to a smaller ring or a larger cog lowers the ratio, easing the effort and raising cadence for the same road speed.
Close ratio cassettes keep the steps between gears small so cadence changes little between shifts, while wide range cassettes trade that smoothness for a very low climbing gear and a very high descending gear. Comparing ratios and development shows where those steps fall and whether a cassette suits the terrain you actually ride.
Continue with the Bike Speed Calculator, Chain Length Calculator, or the Cycling Cadence Calculator — or browse more cycling tools and all sports calculators.
A higher ratio is a harder gear. Each pedal turn moves you further, which suits flat ground and speed, but it takes more force to push.
Every result is computed locally in your browser from the formulas shown above. Nothing you type is uploaded, logged, or stored, and no account is required.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
Free calculator · No signup
Free calculator · No signup
Free calculator · No signup
Free calculator · No signup
Free calculator · No signup
Free calculator · No signup
Content updated: September 2026