📊

Free online statistics calculators

T-scores, z-scores, percentile ranks, weighted averages, standard deviation, correlation, chi-square tests, confidence intervals, sample size, Cronbach's alpha, SPSS output explained — 15 education and statistics tools for homework, theses and surveys, with the formulas shown.

Tools15 tools

📏T-score calculatorConvert a raw score to a T-score (mean 50, SD 10)🔢Z-score calculatorConvert a raw score to a standard (Z) score 📊PR percentile rank calculatorPercentile rank from below-count and tied-count ⚖️Weighted average calculatorValue/weight rows to a weighted average 🏅Class rank percentile calculatorPercentile from a class rank and total count 🔄Normalized score converterLinearly rescale a raw score to a target mean/SD 📉Standard deviation calculatorSample and population standard deviation 💯Percentage calculatorX% of Y, what percent, and percent change 🧪Cronbach's Alpha calculatorScale reliability from a respondents x items matrix 🔍SPSS result interpreterStructured fields for t-test/ANOVA output, plain-language readout 🆔UUID generatorGenerate one or more random v4 UUIDs 📈Correlation calculatorPearson correlation coefficient between two paired data sets 🔲Chi-square test calculatorChi-square test of independence for a contingency table 📐Confidence interval calculatorConfidence interval for a sample mean 🎯Sample size calculatorRequired sample size to estimate a proportion

Which tool for the job?

How many survey responses do I need? → Sample size calculator
95% confidence and a 5% margin are common; the smaller the population, the closer the sample gets to the whole population.
Is my questionnaire scale reliable? → Cronbach's Alpha calculator
An alpha of 0.7+ is usually acceptable; reverse-score negatively worded items first.
Are two categorical variables related? → Chi-square test calculator
For example gender and preference; treat results with care when any expected count is below 5.
Compare scores from different subjects → Z-score calculator
Z-scores put different means and spreads on one scale; for a 50-centred scale, use the T-score calculator.
I can't read my SPSS output → SPSS result interpreter
Paste the output for a plain-language reading of p-values and effect sizes — your research question still decides what it means.

FAQ

Can I use these for a thesis or research report?

Yes, as a calculator and a cross-check; for formal work, make sure the method fits your research design and keep your data and working.

Is what I type stored anywhere?

No. The text and numbers you enter are processed in your browser and never sent to our servers.

Are these tools free? Do I need an account?

Yes, completely free with no usage limits, and no sign-up or login. Signing in with Google is optional and only keeps a record of the tools you've used.

See all tools →