SD, SE & CI Converter
Convert between standard deviation, standard error and confidence interval.
Enter your values to see the result.
Follows the Cochrane Handbook (section 6.5.2): SD = √n × SE, and SE = (upper − lower) ÷ (2 × critical value). For ratios such as odds ratios use the meta-analysis effect converter, which works on the log scale.
Continue your work
- Meta-analysis Effect Converter — Convert ratio CIs to log SEs.
- Mean, SD & SEM Calculator — Compute SD and SEM from raw data.
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Clear instructions
Find steps, examples and limitations below.
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How to use the SD, SE & CI Converter
Convert between standard deviation, standard error and confidence interval.
- 1 Choose whether you have the SD, the SE or a confidence interval.
- 2 Enter the mean, the sample size and the value you have.
- 3 Read the other two measures.
Example and practical tips
A mean of 52.3 with a 95% CI of 48.8 to 55.8 from 25 people gives an SE of 1.70 and an SD of 8.48 using the t distribution.
Further reading
Frequently asked questions
When should I use t rather than z?
The Cochrane Handbook recommends t for samples under about 60, because the interval was probably calculated with t.
Can I use this for odds ratios?
No. Ratio intervals are symmetric on the log scale, so use the meta-analysis effect converter.
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