🔢 Cassette Gear Range Calculator
Calculate your bike's full gear ratio range (highest to lowest) based on your chainring and cassette specs.
Three numbers from three inputs
highest ratio = chainring / smallest cog
lowest ratio = chainring / largest cog
spread = highest / lowestA 50t ring with an 11-32 cassette gives 50/11 = 4.55 at the top, 50/32 = 1.56 at the bottom, and a spread of 2.9×. Notice the chainring cancels out of the spread: 4.55 / 1.56 is the same as 32 / 11. Range is a property of the cassette alone. Changing the ring shifts every gear up or down together without widening anything.
Reading the spread
- Spread is often quoted as a percentage - 2.9× is a "291% range". An 11-34 gives 309%, an 11-42 is 382%, and a 1x mountain 10-52 reaches 520%.
- Wider costs you steps. Spread that range over the same 11 or 12 sprockets and each shift is a bigger jump, which is why an 11-28 feels smooth on a flat road and an 11-34 does not.
- Two chainrings multiply the range beyond the cassette's own. A 50/34 with 11-32 runs 1.06 to 4.55, a spread of 4.3×, at the cost of overlapping gears and front shifts.
- Check the derailleur's rated maximum cog and total capacity before fitting a bigger cassette. Exceeding it means the chain will not clear the largest sprocket.
Frequently asked questions
What gear range does a 50t chainring with an 11-32 cassette give?
1.56:1 to 4.55:1, a 2.9× spread. In the easiest gear the wheel turns about 1.6 times per pedal revolution; in the hardest, 4.5 times.
Does a bigger chainring widen my gear range?
No. It raises the top and the bottom by the same factor. Going 50t to 52t on an 11-32 moves the range to 1.63-4.73, still 2.9×. Only a different cassette changes the spread.
Which cassette do I want for climbing?
The one with the largest big cog your derailleur accepts. A 34t cog behind a 34t ring gives a 1:1 low gear, the usual target for long steep climbs; below that you want a smaller chainring rather than a bigger cassette.