Margin of Error Calculator
Calculate the margin of error for a sample mean at a chosen confidence level.
Calculate
Enter your values below.
Result
Margin of error
0
Formula used
MOE = z × (std dev ÷ √n)
Example: std dev 15, n=30, 95% confidence → margin of error ≈ 5.37.
How to use this calculator
- Enter Standard deviation, Sample size (n).
- Choose Confidence level.
- Press Calculate to see your result instantly.
FAQ
Frequently asked questions
What is margin of error?
The amount added and subtracted from a sample statistic to build its confidence interval.
How does sample size affect margin of error?
A larger sample size shrinks the margin of error, since it's divided by the square root of n.
How does confidence level affect margin of error?
A higher confidence level increases the margin of error, using a larger z critical value.
Where is this different from the Confidence Interval Calculator?
This shows just the margin; the Confidence Interval Calculator also applies it to a specific sample mean.