Originally Posted by ThermionicScott

If I wanted to replicate the gear range I currently had, with the IGH, I would plug in my chainrings and cogs to a gear calculator like this:

Bicycle Gear Calculator

Click on the "Compare two Setups" button, and then select one of the IGH options in the Gearing pulldown menu. Then, you can pick the chainring and cog combo that would replicate your current gearing best.

So, for example: Bicycle Gear Calculator