Impact-Site-Verification: 1fce05f2-a6cf-4f31-8ca1-aaddc332516c

Z-Score Calculator

Standardize a value with z = (x − μ)/σ and see an approximate percentile under a normal curve.

Clear formulas
Educational steps
Detail breakdown

Z-score and approximate percentile from mean and standard deviation you enter.

Limitation: Educational statistics.

Jump to calculator · Sources & review

How to Use the Z-Score Calculator

Z-score and approximate percentile from mean and standard deviation you enter.

1

Open the Z-Score calculator and read field labels.

Match the mode

Educational statistics.

What It Calculates

Z-score and approximate percentile from mean and standard deviation you enter.

Worked Examples

One SD above mean

Inputs

value:80
mean:75
sd:5

Result

z = 1

≈84th percentile.

At the mean

Inputs

value:75
mean:75
sd:5

Result

z = 0

50th percentile approx.

Below mean

Inputs

value:70
mean:75
sd:5

Result

z = −1

≈16th percentile.

Check your mode

Educational statistics.

Frequently Asked Questions

Yes. Results keep the precision shown on the page unless the engine requires integers.

Still have questions about this calculation?

Try the Calculator

Formulas

Standard definitions with assumptions noted below.

Formula

z ​=​ ​(​x − μ​)​​/​σ

Scientific Background

Standard statistics definitions with assumptions stated on-page. Educational only—not professional certification.

Sources & review

Z-Score Calculator documents the references behind its formulas and assumptions. Always treat results as educational estimates, not personalized professional advice.

Last reviewed

July 22, 2026

  • Free Calculator Hub methodology

    Free Calculator Hub

    /methodology

See our methodology and corrections policy.