Z-score Calculator
🎲 Statistics & probability. Use the z-score formula to find z-score, value x, mean μ, standard deviation σ: pick the value you want, type the others, and the answer updates as you go.
How many standard deviations a value is from the mean.
Pick the ○ next to the value you want to find, fill in the others, and it solves as you type.
What each letter means
| Quantity | Unit |
|---|---|
| z-score | no unit |
| Value x | no unit |
| Mean μ | no unit |
| Standard deviation σ | no unit |
Worked example
Find the z-score when Value x = 130, Mean μ = 100, Standard deviation σ = 20.
Using z = (x - μ)/σ: z-score = 1.5.
Frequently asked questions
What is the formula for z-score?
z = (x - μ)/σ. How many standard deviations a value is from the mean.
What do the letters stand for, and what units are used?
z-score, Value x, Mean μ, Standard deviation σ.
How do you calculate z-score?
Put the values into z = (x - μ)/σ. For example, with Value x = 130, Mean μ = 100, Standard deviation σ = 20, z-score = 1.5.
Can I solve for a different value?
Yes. In the calculator above, pick the circle next to any value (z-score, value x, mean μ, standard deviation σ) and fill in the others: it rearranges the formula for you.
