Statistics calculators

Probability, sampling, and descriptive statistics made readable.

Means, medians, standard deviations, confidence intervals, and sample size planning — with formulas and worked examples for each tool.

Calculators

103

Topics: All Descriptive (29) Probability (35)

Statistics

Paired Samples Difference t-Test Calculator

Calculates the t-statistic for a paired t-test from the mean difference, standard deviation of differences, and sample s...

basic

14,018 4.3 1 min

Statistics / Probability

Poisson Distribution Probability Calculator

Calculates Poisson probabilities: P(X=k) = e^(−λ)·λᵏ/k!, and the cumulative P(X≤k) by summing from 0 to k. Used for coun...

basic

21,876 4.3 1 min

Statistics

Poisson PMF / CDF Expected Value Calculator

Calculates Poisson probability mass function P(X = k) and cumulative distribution P(X ≤ k) for a given rate λ and event...

basic

21,493 5.0 1 min

Statistics / Probability

Minimum Detectable Effect from Sample Size and Alpha Calculator

Calculates the minimum detectable effect MDE = (z_α + z_β) × √(2σ²/n), where z_α is the critical value and z_β correspon...

basic

18,218 4.1 1 min

Statistics / Descriptive

Weighted Mean from Values and Frequencies Calculator

Calculates x̄_w = Σ(w_i · x_i) / Σw_i for up to six value/weight pairs. Used in grade calculations, portfolio returns, a...

basic

6,501 5.0 1 min

Statistics

Cohen's d Standardised Effect Size Calculator

Calculates Cohen's d standardised effect size between two groups from their means and pooled standard deviation.

basic

2,284 4.5 1 min

Statistics

Z-Test One-Proportion Significance Calculator

Calculates the z-statistic for a one-sample proportion test comparing an observed sample proportion against a known or h...

basic

1,889 4.5 1 min

Statistics / Descriptive

Interquartile Range from Q1 and Q3 Calculator

Calculates IQR = Q3 − Q1. Also computes the lower and upper fences for outlier detection: lower = Q1 − 1.5×IQR, upper =...

basic

23,837 4.1 1 min

Statistics

Normal Distribution CDF Area & Percentile Calculator

Calculates the cumulative area under the normal curve (P(X ≤ x)) and the percentile rank for a value x given mean μ and...

basic

16,748 4.9 1 min

Statistics / Probability

A/B Test Required Sample Size Calculator

Calculates the sample size per variant needed for an A/B test: n ≈ 2 × [z_α/2 + z_β]² × p̄(1−p̄) / (p₁−p₂)², using the p...

basic

13,299 4.8 1 min

Statistics

Exponential Distribution λ PDF & CDF Calculator

Calculates the PDF, CDF, mean, and variance of an exponential distribution from rate parameter λ at a given value x.

basic

10,944 4.4 1 min

Statistics / Probability

Multinomial Coefficient for Three Groups Calculator

Calculates the multinomial coefficient n!/(n₁!·n₂!·n₃!) and the probability of each outcome when items are drawn from a...

basic

5,028 4.9 1 min

Statistics

Sample Size for Proportion Study Calculator

Calculates the minimum sample size needed to estimate a proportion with a specified margin of error and confidence level...

basic

722 4.0 1 min

Statistics

Weibull Shape-Scale Reliability Calculator

Calculates Weibull reliability R(t), failure probability, hazard rate, and MTTF from shape parameter β and scale paramet...

basic

24,985 4.6 1 min

Statistics

Chi-Square Independence Test Calculator

Calculates the chi-square statistic for a 2×2 contingency table to test for independence between two categorical variabl...

basic

21,983 4.2 1 min

Statistics / Probability

Bayesian Posterior from Beta Prior and Binomial Likelihood Calculator

Updates a Beta(α, β) prior with n trials and k successes to get the posterior Beta(α+k, β+n−k). Returns posterior mean,...

basic

21,784 4.1 1 min

Statistics

Confidence Interval for Proportion Calculator

Calculates the confidence interval for a population proportion from sample proportion, sample size, and chosen confidenc...

basic

15,757 4.4 1 min

Statistics / Descriptive

Normal Distribution Z-Score and Percentile Calculator

Calculates z-score z = (x − μ)/σ and approximate one-tailed percentile using the rational approximation of the standard...

basic

13,249 5.0 1 min

Statistics / Probability

Pearson Chi-Square from Contingency Table Calculator

Calculates χ² = Σ(O−E)²/E from observed and expected frequencies in up to a 4-cell (2×2) contingency table, and indicate...

basic

807 4.0 1 min

Statistics / Probability

Expected Value of a Discrete Distribution Calculator

Calculates the expected value E[X] = Σ xᵢ·P(xᵢ) and variance Var[X] = Σ(xᵢ−μ)²·P(xᵢ) for a discrete probability distribu...

basic

24,909 4.2 1 min

Statistics

Pearson r Correlation Strength Calculator

Calculates the Pearson product-moment correlation coefficient r and r² from summary statistics (means, standard deviatio...

basic

23,816 4.4 1 min

Statistics / Probability

Type II Error Rate (Beta) from Power Calculator

Calculates type II error rate β = 1 − power, type I error rate α, and the four outcomes of a hypothesis test with their...

basic

21,866 4.4 1 min

Statistics / Probability

Erlang B and C Queueing Theory Calculator

Calculates the Erlang B formula for call blocking probability and Erlang C for probability of queuing in a M/M/c telepho...

basic

18,221 4.8 1 min

Statistics

Statistical Power & Type II Error Calculator

Calculates the statistical power of a one-sample z-test from effect size, sample size, and significance level.

basic

5,509 4.2 1 min

Showing 49 to 72 of 103 results

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Means, medians, standard deviations, confidence intervals, and sample size planning — with formulas and worked examples for each tool.

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Statistics calculators

Paired Samples Difference t-Test Calculator

Poisson Distribution Probability Calculator

Poisson PMF / CDF Expected Value Calculator

Minimum Detectable Effect from Sample Size and Alpha Calculator

Weighted Mean from Values and Frequencies Calculator

Cohen's d Standardised Effect Size Calculator

Z-Test One-Proportion Significance Calculator

Interquartile Range from Q1 and Q3 Calculator

Normal Distribution CDF Area & Percentile Calculator

A/B Test Required Sample Size Calculator

Exponential Distribution λ PDF & CDF Calculator

Multinomial Coefficient for Three Groups Calculator

Sample Size for Proportion Study Calculator

Weibull Shape-Scale Reliability Calculator

Chi-Square Independence Test Calculator

Bayesian Posterior from Beta Prior and Binomial Likelihood Calculator

Confidence Interval for Proportion Calculator

Normal Distribution Z-Score and Percentile Calculator

Pearson Chi-Square from Contingency Table Calculator

Expected Value of a Discrete Distribution Calculator

Pearson r Correlation Strength Calculator

Type II Error Rate (Beta) from Power Calculator

Erlang B and C Queueing Theory Calculator

Statistical Power & Type II Error Calculator