Starlight Tools directory

Statistics & Probability Calculators

18 free, browser-based tools. No account required.

Free to use
Runs in your browser
No account required

Analyze datasets, calculate probabilities, explore distributions, and plan studies with private browser-based statistics tools. Start with the Probability Calculator, Normal Distribution Calculator, Correlation Coefficient Calculator, or Mean, Median, Mode Calculator.

Yellow star mascot spotting a data outlier beyond an IQR fence

Outlier Calculator

Find potential outliers with IQR fences, z-scores, and modified z-scores, then compare agreement and download row-level results. v1.0

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$Yellow star mascot converting fractional, decimal, and percentage odds$

Odds & Probability Converter

Convert decimal, fractional, and American moneyline odds with implied probability, formulas, and optional stake returns. v1.0

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Yellow star mascot balancing probability-weighted outcomes for expected value

Expected Value Calculator

Calculate expected value, variance, standard deviation, E(X²), and every weighted contribution for discrete outcomes. v1.0

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Yellow star mascot measuring data spread around the mean

Variance Calculator

Calculate population and sample variance, standard deviation, and every squared deviation with transparent steps. v1.0

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Yellow star mascot marking percentile rank along ordered data

Percentile Calculator

Calculate percentile rank, any percentile value, quartiles, and IQR with selectable tie and interpolation methods. v1.0

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Bayes’ Theorem Calculator

Update a prior probability with evidence using likelihoods, total probability, posterior odds, and transparent calculation steps. v1.0

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Margin of Error Calculator

Calculate margin of error or required sample size for a proportion or mean, with custom confidence and finite population correction. v1.0

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Confidence Interval Calculator

Calculate intervals for means, proportions, and independent-group differences with t, z, Wilson, Welch, and Newcombe methods. v1.0

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Yellow star mascot comparing null and alternative hypotheses with a rejection region

Hypothesis Test Calculator

Run z-tests and t-tests for means and proportions with p-values, critical regions, decisions, formulas, and assumptions. v1.0

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Correlation Coefficient Calculator

Calculate Pearson r and Spearman rho with two-sided p-values, significance, confidence limits, ranks, and a scatterplot. v1.0

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Yellow star mascot shading probability beneath a normal distribution curve

Normal Distribution Calculator

Calculate normal CDFs, tails, ranges, percentiles, and critical values with z-scores and a shaded bell curve. v1.0

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Yellow star mascot arranging events for union, intersection, and conditional probability

Probability Calculator

Calculate unions, intersections, conditional probabilities, and complements with formulas, validation, and steps. v1.0

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Yellow star mascot calculating the average of 2, 4, and 6

Average (Mean) Calculator

Compute the arithmetic mean instantly, with the sum, count, minimum, maximum, range, and calculation steps. v1.0

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Yellow star mascot demonstrating mean, median, mode, and range

Mean, Median, Mode Calculator

Calculate the mean, median, mode, range, quartiles, and IQR for a set of numbers. v1.0

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Yellow star mascot measuring a z-score from the mean on a bell curve

Standard Deviation & Z-Score

Find the mean, variance, population or sample standard deviation, and per-value z-scores. v1.0

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Yellow star mascot comparing binomial trials with Poisson event rates

Binomial & Poisson Calculator

Calculate PMF, CDF, tail and range probabilities with expected value, variance, tables, and charts. v1.0

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Sample Size Calculator

Plan a two-sample t-test by solving for sample size, achieved power, or minimum detectable effect. v1.0

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Markov chain random walk tool with transition matrix and state graph

Markov Chain Calculator & Simulator

Analyze transition matrices, multi-step probabilities, stationary distributions, and simulated random walks. v1.0.0

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About These Statistics & Probability Calculators

These calculators cover descriptive statistics, probability distributions, study planning, and stochastic processes. Calculations run locally in your browser, and the tools show formulas, working, tables, or charts where useful.