Lego Gear Ratio Calculator

This tool shows possible ways to connect a given pair of gears.
Maximum error: mm

This is a web app to find sequences of Lego Technic gears that produce a given transmission ratio.

The Edit gear sequence tab allows you to enter a sequence of gears and calculate its transmission ratio.

The Fit Gears tab shows you possible ways of connecting a given pair of two gears. If the axes of the driver and follower gear are offset in two different directions, it's a 2D connection. These connections will be preferred in the Search tab over pairs of gears that can't be connected otherwise.

If you search for accurate solutions and your target ratio has a prime factor in the numerator or denominator that is not present in any of the included gears, it will search for solutions with differential gears. In this case, no solution without differential gears is possible. Click here for an example. If both the numerator and denominator contain missing prime factors, the result will contain two differentials.

If you need additional gears, check out my designs of 3D printable Lego compatible gears with custom teeth counts.

Also check out my Part Designer app that lets you design and 3D print custom Lego Technic compatible structural parts..

This app is free and open source. You can find the source code on Github.

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