Critical Value Calculator

Find critical values for the z and t distributions at any α level (one- or two-tailed) - used for hypothesis tests and confidence intervals.

Frequently Asked Questions

What is a critical value?

The cutoff that defines the rejection region in a hypothesis test, or the multiplier in a confidence interval. Compare your test statistic to it to decide reject/fail-to-reject.

z* vs t*?

Use z* when the population SD σ is known or n is large. Use t* when σ is unknown and you estimate it from the sample.

How do α and confidence level relate?

Confidence level = 1 − α. A 95% CI corresponds to α = 0.05.

Important Disclaimer: Estimates for informational purposes only.

This calculator provides estimates for informational purposes only. Results are based on assumptions and may not reflect actual outcomes. Consult qualified professionals in relevant fields before making important decisions based on these results.