This is a calculator for normal distribution related things, just modify one number and all the other numbers will update as you type. Calculations are done with JS double-precision floats, I don't guarantee its accuracy past 7 standard deviations.
Also known as the z-score.
The fraction of things with a value less than the Z-score or X sigma.
The percentage of things with a value less than the Z-score.
One in X things will have a value greater than the threshold.
The Z-score represented as an IQ.
This was hacked together in 2 hours by Tristan Hume, the source is on Github. File an issue or email me with any requests/bugs.