Computes areas (probabilities) under a normal curve. With the mean at 0 and SD at 1, the boundary is a z-score.
The buttons above the chart choose which area is shaded and reported:
The calculator works in both directions — edit whichever value you know:
You can also drag the boundary line(s) directly on the chart. The banner beside the buttons reports the current area.
Set Mean (μ) and SD (σ) to match your distribution. Leaving them at 0 and 1 gives the standard normal, so the boundary reads as a z-score.
New to this tool? Walk through it step by step.