p is about 0.05
P-value Calculator
Use this free p-value calculator to estimate a normal-curve p-value from a z-score, choose left-tailed, right-tailed, or two-tailed mode, and see the tail areas.
Formula steps Examples included Copy results Private history
Two-tailedp = 0.0499956522
- Left tail
- 0.9750021739
- Right tail
- 0.0249978261
- Z-score
- 1.96
Steps
- Use the standard normal curve where mean is 0 and standard deviation is 1.
- Find the left-tail area for z = 1.96.
- Double the smaller tail area for a two-tailed p-value.
- The p-value is 0.0499956522.
How to use the p-value calculator
- Choose left-tailed, right-tailed, or two-tailed mode.
- Enter the z-score from your statistics problem.
- Press Calculate p-value to see the standard-normal tail areas.
- Use the result as a quick normal-curve estimate, then check whether your assignment needs a different distribution.
Common uses
Estimate a p-value from a z-score in a statistics example.
Compare left-tailed, right-tailed, and two-tailed test choices.
See the left and right standard-normal tail areas.
Check introductory hypothesis-testing work before writing an interpretation.
Examples
p is about 0.05
p is about 0.10
Frequently asked questions
Quick answers about formulas, inputs, examples, result copying, and private in-browser history.
What does this P-value Calculator use?
It estimates p-values from a z-score using the standard normal curve. It is for z-test style examples, not every statistical test.
Which tail should I choose?
Choose right-tailed when unusually high values matter, left-tailed when unusually low values matter, and two-tailed when differences in either direction matter.
What does a smaller p-value mean?
A smaller p-value means the observed z-score is farther into the tail of the comparison curve. It does not prove a claim by itself.
Is this the same as a t-test p-value?
No. A t-test uses a t distribution and degrees of freedom. This calculator uses the standard normal distribution from a z-score.
Why is the two-tailed value doubled?
A two-tailed test counts extreme results in both directions, so it doubles the smaller tail area while keeping the result no higher than 1.
Is my z-score history private?
Yes. Recent answers stay only in your current browser tab and are not sent to a server.