Uncertainty & Error-Bar Visualiser

Enter an estimate and its uncertainty, and see the range of values it plausibly covers. This tool shows how sample size and spread shape that range — and why overlapping error bars are not proof of no difference.

How it works

You give an estimate (a mean), how spread out the data are (a standard deviation with a sample size, or a standard error directly), and a confidence level. The standard error measures how much the estimate would wobble from sample to sample; when it comes from a sample standard deviation, the tool uses the Student-t multiplier, and when you supply a standard error directly, it uses the z multiplier. The shaded region is where the estimate plausibly lives at your chosen level — not a guarantee, just a calibrated range.