📊 Statistics
P-Value Calculator
The p-value is the probability of seeing a result at least this extreme if the null hypothesis were true. It is not the probability that the null hypothesis is correct, and it says nothing about how large the effect is. This calculator uses a z-test, which assumes you know the population standard deviation or have a large sample.
How it works
Sample mean
Hypothesised mean
Standard deviation
Sample size
Test type
P-value
Z statistic
One-tailed p-value
Two-tailed p-value
Standard error
Frequently asked questions
How do I use the P-Value Calculator?
Fill in the fields above — the result recalculates instantly as you type. Everything runs in your browser, so the values you enter are never collected or stored.
Is this calculator free?
Yes. It is completely free, requires no account, and works on phones, tablets and desktops.