How to use the P-value Calculator
Estimate p-value from z statistic, probability, left z bound with the P-value Calculator. It includes Two-sided P-value, Left-tailed P-value, Right-tailed P-value, Area from center to Z, Central probability, Probability between bounds workflows, so choose the one that matches the values you actually know. Use it to check the arithmetic while keeping the displayed method and entered values with your work.
Step by step
- For the P-value, enter z statistic, probability, left z bound, right z bound. Keep each value in the unit displayed beside its field.
- Review the selected P-value workflow and inputs, then read p-value in the result panel.
- Change one P-value assumption at a time to compare scenarios. Use Reset to restore this tool's worked example values.
How the calculation works
Converts between Z statistics and left-tail, right-tail, center, bounded, or two-sided standard-normal probabilities.
Worked example
In the P-value worked example, z statistic 1.96, probability 0.05, left z bound -1, right z bound 1 produces p-value of 0.04999565. Two-sided P-value: Converts between Z statistics and left-tail, right-tail, center, bounded, or two-sided standard-normal probabilities. Review the displayed units before comparing the result.
Understanding the result
The P-value reports p-value. Use it to check the arithmetic while keeping the displayed method and entered values with your work. The result depends on the entered values, selected mode, and displayed mathematical assumptions.
How to check the answer
Check the P-value answer by substituting p-value back into the stated relationship. Test a simple value such as zero, one, or an equal pair, then confirm that sign, scale, units, and rounding match Converts between Z statistics and left-tail, right-tail, center, bounded, or two-sided standard-normal probabilities.
Common questions
What does the P-value calculate?
Estimate p-value from z statistic, probability, left z bound with the P-value Calculator.
Which P-value inputs have the biggest effect?
p-value responds directly to z statistic, probability, left z bound, right z bound. Change one input while holding the others constant to see its effect.
Is the P-value result exact?
The result depends on the entered values, selected mode, and displayed mathematical assumptions. Recheck z statistic, probability, left z bound and use p-value only for a decision where that level of precision is appropriate.