Turn 0-10 survey responses into a Net Promoter Score, with promoters, passives and detractors broken out.
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Statistics calculators that show their work
For students, researchers and analysts. Every answer comes with the formula, each step of the working and a plain-English explanation of what it means.
- Step-by-step working
- Plain-English answers
- Charts you can download
Exam scores have a mean of 70 and a standard deviation of 10. You scored 85. How unusual is that?
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Write the formula
z = x − μσ
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Substitute x = 85, μ = 70, σ = 10
z = 85 − 7010 = 1510
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Divide
z = 1.5
What it means: 85 is 1.5 standard deviations above the mean, higher than about 93% of scores. Try the z-score calculator
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Free, no sign-up
Every tool is free to use, with no account or email required.
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Every step shown
Formulas, substitutions and intermediate values, laid out like a worked solution.
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Private by design
Calculations run in your browser. Your data is never uploaded.
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Charts as PNG
Download sharp, labeled charts for reports, homework and slides.
14 free tools
Pick a tool
Each one shows the working, explains the result and lets you download the chart.
Calculators
Enter your numbers and get the answer, the formula, each step of the working and what the result means.
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Find how many standard deviations a value sits from the mean, plus its percentile.
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Find probabilities above, below or between values on a normal curve, or the value for a given percentile.
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Get the p-value from a z, t, chi-square or F statistic, one- or two-tailed, with the reasoning shown.
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Confidence intervals for a mean or a proportion, from raw data or summary statistics, with the margin of error explained.
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One-sample, two-sample and paired t-tests with the t statistic, p-value, effect size and every step shown.
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Pearson or Spearman correlation for paired data, with r², a significance test and every step shown.
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Find the mean, median, mode and range of a list of numbers, with each one worked out step by step.
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Sample or population standard deviation and variance from a list of numbers, every step written out.
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Work out how many responses you need for a given confidence level and margin of error.
Chart makers
Paste your data and download a clean, labeled chart for a report, assignment or slide.
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Paste x and y values to get a scatter plot with a trend line and correlation, ready to download.
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Enter categories and values to build a clean bar graph you can download as an image.
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Paste a list of numbers to get a histogram with sensible bins, a frequency table and a downloadable PNG.
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Make box-and-whisker plots for one or more groups, with the five-number summary and outliers marked.
How it works
From raw numbers to a result you can explain
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Enter your data
Type numbers, paste a column from Excel or Google Sheets, or start from the built-in example.
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Follow the working
See the formula, how your numbers go into it and every step to the final, highlighted answer.
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Understand and share
Read a plain-English explanation of the result, then download the chart for your report.
Why StatHow
More than just the answer
A number on its own doesn't help you check homework, explain a result to your manager or learn the method. StatHow is built to show you how the answer was reached.
| Feature | StatHow | Answer-only calculators |
|---|---|---|
| Final answer | Yes | Yes |
| Formula with every symbol explained | Yes | Rarely |
| Step-by-step working with your numbers | Yes | Rarely |
| Plain-English interpretation | Yes | Rarely |
| Downloadable chart | Yes | Rarely |
| Data stays in your browser | Yes | Varies |