Z-Score Calculator
Express a value’s distance from the mean in standard deviations.
Formula
- Use the units shown beside each field.
- Results update automatically whenever you change an input.
- Displayed values use up to four decimal places, or scientific notation for very small or large numbers. Calculations use standard floating-point arithmetic; exact integer and fraction tools identify their own precision rules.
Example Calculation
- Value: 85
- Mean: 70
- Standard deviation: 10
85 is 1.5 standard deviations above a mean of 70 when σ=10.
Frequently asked questions
How do I use this calculator?
Enter value, mean, standard deviation. The result updates automatically. Use Reset to restore the example values.
What method does it use?
z = (x − μ) / σ. Follow the units and definitions shown with the inputs to apply this relationship consistently.
Why might a rounded result differ?
The calculation keeps full numeric precision internally, then rounds the displayed result. Rounding intermediate steps by hand can produce a slightly different answer.
Are my inputs saved online?
No. This calculator processes your inputs in your browser. A recently used list stores only calculator names on this device, not your entered values.
Check the assumptions and units before using this result. Read about calculation methods.