You're not the only one. I recently took up running and didn't particularly like any of the existing running pace calculators, so I made my own: https://calcubest.com/health/runningpace

And then kinda realized that there were others I wanted to have, and a few I thought others might want, so I added more.

A calculator is simple enough that it's fun to work on one when I need a break from something more complex but want to be able to do something other than doom scrolling. So now every couple of weeks I add another one.