Analyze Benford's Law Fraud Detector Online
Test whether a numeric column follows Benford's first-digit law — chi-squared conformity verdict, expected-vs-observed chart, and the rows driving the deviation. Use Benford's Law Fraud Detector in your browser with no signup, no daily limit, and no backend processing for tool input.
Problem
You need to understand a dataset or payload before deciding what to clean, transform, or export.
What to do
Analysis gives a fast first pass on quality and structure. Use the findings to decide whether the data is ready or needs more cleanup.
- 1Load the dataset or payload into Benford's Law Fraud Detector.
- 2Review counts, types, warnings, and summaries.
- 3Use the findings to clean, validate, visualize, or export the data.
Use the browser tool
Benford's Law Fraud Detector tests whether the leading digits of a numeric column follow the distribution that naturally occurring numbers tend to follow — about 30% starting with 1, falling away to under 5% starting with 9. It reports a chi-squared conformity verdict, charts expected against observed, and lists the rows driving the deviation. It is a screening tool used in forensic accounting and audit: a failed test is a reason to look closer, never evidence of anything on its own.
People also ask
- Why should 1 be the leading digit 30% of the time?
- Because many real quantities grow multiplicatively and span several orders of magnitude. Under that kind of growth a value spends longer between 1 and 2 than between 8 and 9, so leading 1s accumulate. Formally the expected proportion is log10(1 + 1/d).
- Which data should not be tested?
- Anything assigned rather than measured or accumulated — invoice numbers, ids, postcodes, phone numbers — and anything with imposed bounds, like values capped at an approval limit. These fail the test for entirely innocent reasons.
- Does failing the test mean fraud?
- No. It means the digit distribution is not Benford. That is a prompt to look at why, and the most likely answer is that this data was never expected to conform.