It originally ran on Windows Mobile, since almost nobody used computers for DJing back then, but I'm posting a Windows version here, since almost all of us use some kind of DVS system that runs on computers.
It's really simple to use. Input the original BPM on the left text box, and the target BPM on the right one. Press "Calculate" or Enter, and Calculate will turn in the amount of pitch you need to change, to get to the target BPM. Results are rounded on two decimals.
This was compiled some time ago for personal use, thats why it doesn't have any "About" info, or link back to this site. Please don't rip off my work and pose it as yours.
Requires some version of .NET framework, i think it's compiled with 2.0, but install the latest anyway.