Timing Pulley/Belt sizing software

What's currently available for calculating pulley spacing/belt sizing?

Or, if somebody happens to have some already installed, and willing to run a few calcs, I currently have a 10:20 L(3/8" pitch) setup linked with a 150L (40tooth 15"/381mm) belt.
I'm wanting to change to a 16:20 set-up, and need to know the difference in centre distance between the pulleys using the existing belt, and the next commonly availble size up which would appear to be a 187L (50tooth) belt.

Thanks!

Try my spreadsheet:

http://www.mycncuk.com/forums/machin...t-lengths.html

Changethe 'Belt pitch' to 9.525mm and it'll work.

Thanks for that.

15mm nearer for the same belt, or 30+mm for the longer belt. I'll need to do some measuring in the morning.

Edit: Ooops ! wrong thread, please ignore.

https://sdp-si.com/eStore/CenterDistanceDesigner