Z-Score Calculator
Standard score and the probability either side of it.
Z-score
1.5
1.5 standard deviations above the mean
Percentile
93.32%
Area below
0.9332
Area above
0.0668
ShowHide the working
- 1z = (x − μ) ÷ σ = (85 − 70) ÷ 10 = 1.5
- 293.32% of a normal distribution lies below this value
Formula
z = (x − μ) ÷ σHow it works
A z-score says how many standard deviations a value sits from the mean, and its percentile under a normal distribution.
Example
x = 85 with μ = 70 and σ = 10 gives z = 1.5, the 93rd percentile.
More in Statistics
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- Normal Distribution Calculator
- Correlation Calculator
- Linear Regression Calculator
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About the Z-Score Calculator
Standard score and the probability either side of it. It sits in the Statistics section of NWS Calc, a free collection of calculators that run entirely in your browser. There is no signup, no paywall and no tracking — open the page, enter your numbers, get an answer.
Frequently asked questions
- Is the Z-Score Calculator free to use?
- Yes. Every calculator on NWS Calc is completely free, with no signup, no usage limits and no ads.
- Does my data leave my device?
- No. The Z-Score Calculator runs entirely in your browser using JavaScript. Nothing you type is uploaded, logged or stored on a server.
- Can I use the Z-Score Calculator on my phone?
- Yes. The page is fully responsive and works in any modern mobile or desktop browser — there is nothing to install.
- What else is in Statistics?
- Mean, deviation, regression, probability and distributions. You can browse the full Statistics category for related calculators.