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SCIENCE LAB
Compute a 90%, 95%, or 99% confidence interval for a dataset mean using the t-distribution with a small-bias z approximation.
WHAT THIS DOES
Runs entirely in your browser.
/tools/confidence-interval-calculatorconfidence-interval-calcv4.0.0LOCAL · LOCAL RUNIMPLEMENTED — This workbench is functional in the current release.Presets for this workbench
No preset yet. A preset stores the values in this form — never the result — and only for workbenches that run entirely in your browser.
Collections
Saved on this device only. Turn on sync to carry them to another device.
BATCH / ONE VALUE PER LINE
Up to 200 lines, one at a time, in this browser. Each line takes the place of values and everything else stays as you set it. Nothing is uploaded, and the row limit is not exceeded silently.
METHOD / LOCAL RUN
CI = mean ± z × (sample stddev / √n). Uses fixed z-values: 1.645 (90%), 1.96 (95%), 2.576 (99%).
Boundary: Normal-distribution approximation. Not exact for very small samples (n < 30).
The calculation or transformation runs in your browser using the values entered above. No input is sent to UtilityForge for this tool.
EXAMPLES / LOCAL RUN FIXTURES
FAQ
No. The confidence interval calculator runs entirely locally.
The workbench states the exact method behind every result — the formula or procedure this page runs — so you can verify the computation instead of trusting a black box.
No. This workbench runs in the page: Values (comma-separated), Confidence level are read by the code your browser already downloaded, and UtilityForge receives neither the values nor the result.
Normal-distribution approximation. Not exact for very small samples (n < 30).
RELATED TOOLS
LOCAL — Runs entirely in your browser.
COMMON USE CASES / SOURCE NOTE
Last reviewed:
Source information: Local mean/stddev plus fixed z-value; not a substitute for statistical software.