[nritchie]

Here (https://uncertainty.nist.gov/) is another similar Monte Carlo-style calculator designed by the statisticians at NIST. It is intended for propagating uncertainties in measurements and can handle various different assumed input distributions.

[filiph]

I think I was looking at this and several other similar calculators when creating the linked tool. This is what I mean when I say "you'll want to use something more sophisticated".

The problem with similar tools is that of the very high barrier to entry. This is what my project was trying to address, though imperfectly (the user still needs to understand, at the very least, the concept of probability distributions).