Statistics & Probability Calculators
Paste a data set and get the full picture: averages, spread, quartiles and z-scores; hypothesis tests, confidence intervals and sample sizes; correlation and regression; probability distributions. Plus grade and GPA tools for students.
42 calculators
Most used
- Confidence Interval CalculatorBuild a confidence interval for a population mean or proportion from summary statistics or raw data, with the critical value, margin of error and every step.
- Final Grade CalculatorEnter your current grade and the final exam's weight to see the score you need on the final, or what your grade becomes for any final score.
- GPA CalculatorEnter letter grades and credit hours to find your semester GPA on the 4.0 scale, then add past credits to get your cumulative GPA.
- Mean, Median, Mode CalculatorEnter a list of numbers to find its mean, median, mode and range, with the sorted data and a frequency table.
- P-Value CalculatorTurn a test statistic from a z, t, chi-square or F test into its p-value, see the matching critical value, and get a plain-language verdict at your α.
- Sample Size CalculatorFind the sample size for a survey or estimate, or the number per group needed to detect a difference with a chosen power, with the formula worked out.
Descriptive statistics 15
- Coefficient of Variation CalculatorFind the coefficient of variation, the standard deviation as a percentage of the mean, and compare how variable two data sets are relative to their size.
- Descriptive Statistics CalculatorPaste a data set to get every common summary statistic in one table, from mean and standard deviation to quartiles, skewness and a histogram.
- Five Number Summary CalculatorGet the minimum, first quartile, median, third quartile and maximum of your data, plus the IQR and a box-and-whisker plot.
- Frequency Table CalculatorTurn raw numbers or text responses into a frequency table with relative and cumulative frequencies, class midpoints and a histogram or bar chart.
- Mean CalculatorPaste a list of numbers to get the arithmetic, geometric, harmonic and root-mean-square averages, with the steps for each one.
- Mean, Median, Mode CalculatorEnter a list of numbers to find its mean, median, mode and range, with the sorted data and a frequency table.
- Moving Average CalculatorSmooth a data series with a simple, exponential or weighted moving average, chart it against the raw values, and check how well it forecasts the next period.
- Outlier CalculatorFlag unusual values with three methods side by side (IQR fences, z-scores and modified z-scores) and see how much the outliers move the mean and SD.
- Quartile CalculatorFind the first, second and third quartiles, the interquartile range and the 1.5 × IQR outlier fences, with four quartile methods compared.
- Range CalculatorFind the range, minimum, maximum and midrange of a list of numbers, with the interquartile range for comparison.
- Standard Deviation CalculatorPaste a list of numbers to get the sample or population standard deviation, variance, mean and standard error, with every step.
- Standard Error CalculatorFind the standard error of a mean, a proportion or a difference in means, with a 95% interval and a table showing how the error shrinks as samples grow.
- Sum CalculatorPaste a column or list of numbers to get the total, count and average, plus a running total after each value.
- Variance CalculatorFind the sample or population variance of a data set, with a table of squared deviations and both the definition and shortcut formulas.
- Weighted Average CalculatorEnter values and their weights to get the weighted average, the sum of weights and each value's contribution, with every step shown.
Distributions & scores 5
- Normal Distribution CalculatorEnter a mean and standard deviation to find the probability below, above, between or outside values, or the cutoff for a given probability.
- Percentile CalculatorFind the value at a given percentile of your data, or the percentile rank of a particular value, using the method your software or class expects.
- Statistics FormulasA one-page reference of core statistics formulas, with every formula evaluated on a data set you can edit.
- Stem and Leaf Plot GeneratorTurn a list of numbers into a stem-and-leaf plot with a key, choosing the leaf unit and whether to split each stem.
- Z-Score CalculatorTurn a raw score into a z-score, look up its normal probabilities and percentile, or work backward from a percentile to a z-score.
Hypothesis tests & confidence intervals 8
- Chi-Square Test CalculatorTest whether counts match an expected distribution, or whether two categorical variables are related, with expected counts, cell contributions and the p-value.
- Confidence Interval CalculatorBuild a confidence interval for a population mean or proportion from summary statistics or raw data, with the critical value, margin of error and every step.
- Margin of Error CalculatorGet the plus-or-minus margin for a poll result or an average, test whether one option's lead is real, and see how sample size changes the margin.
- One-Way ANOVA CalculatorTest whether several group means differ, with a complete ANOVA table, F statistic, p-value, effect sizes and a summary of each group.
- P-Value CalculatorTurn a test statistic from a z, t, chi-square or F test into its p-value, see the matching critical value, and get a plain-language verdict at your α.
- Sample Size CalculatorFind the sample size for a survey or estimate, or the number per group needed to detect a difference with a chosen power, with the formula worked out.
- T Critical Value CalculatorLook up the critical value of Student's t for any degrees of freedom, significance level or confidence level, with a printable t-table and a shaded curve.
- T-Test CalculatorCompare a mean with a target, two independent groups, or paired measurements, and get the t statistic, p-value, confidence interval and effect size.
Probability 5
- Binomial Probability CalculatorCalculate the probability of exactly, at most, at least or between k successes in n independent trials, with the mean, SD, a bar chart and a full table.
- Birthday Paradox CalculatorCalculate the probability that at least two people in a group share a birthday, or the group size needed for any target chance, with a probability curve.
- Expected Value CalculatorFind the long-run average of a game, bet or decision from its outcomes and probabilities, with the variance, standard deviation and totals over many plays.
- Poisson Distribution CalculatorCalculate the chance of a given number of events when they happen at a known average rate, with exact and cumulative probabilities, a chart and a table.
- Probability CalculatorCombine two event probabilities with the addition, multiplication and complement rules, get conditional probabilities and see every region on a Venn diagram.
Correlation & regression 3
- Correlation Coefficient CalculatorMeasure how strongly two variables move together with Pearson's r and Spearman's ρ, plus r², significance, a confidence interval and a scatter plot.
- Covariance CalculatorFind the sample or population covariance of two variables, see every deviation product and the covariance matrix, and compare it with the correlation.
- Linear Regression CalculatorFit the least-squares line through paired data and get the equation, R², slope significance, predictions with intervals, residuals and a scatter plot.
Grades & GPA 4
- Final Grade CalculatorEnter your current grade and the final exam's weight to see the score you need on the final, or what your grade becomes for any final score.
- GPA CalculatorEnter letter grades and credit hours to find your semester GPA on the 4.0 scale, then add past credits to get your cumulative GPA.
- Grade CalculatorEnter scores and weights for each grading category to get your current weighted grade, letter grade and the score you need on what is left.
- Vote Percentage CalculatorEnter vote counts for each candidate or option to get each share of the vote, the margin of victory and whether a winning threshold was met.
Text & counting tools 2
Guides
- How to Calculate a Confidence Interval for a Mean or ProportionA confidence interval is an estimate plus or minus a margin of error. Step-by-step examples for means and proportions, critical values and sample size.
- How to Calculate a Z-Score and Turn It Into a PercentileA z-score counts how many standard deviations a value sits from the mean. Learn the formula, how to read it as a percentile and where it breaks down.
- How to Calculate Your GPA (Semester, Cumulative and Weighted)Convert grades to points, weight them by credit hours, and divide. Step-by-step semester and cumulative examples, weighted GPAs and how to raise yours.
- How to Calculate Standard Deviation by Hand (Step by Step)Five steps from raw data to standard deviation, with a fully worked example, the n − 1 rule for samples, a faster shortcut formula and grouped data.
- How to Calculate a Weighted Average (Grades, Prices and More)Multiply each value by its weight, add the products and divide by the sum of the weights. Worked examples for grades, prices, speeds and percentages.
- How to Find Quartiles and the Interquartile Range (IQR)Sort the data, split it at the median, and find the median of each half. Worked odd and even examples, outlier fences, and why methods disagree.
- Mean vs Median vs Mode: Which Average Should You Use?The mean, median and mode each answer a different question about the middle of your data. Learn how to find them and which one tells the honest story.
- What Is a P-Value? A Plain-English Explanation With ExamplesA p-value measures how surprising your data would be if nothing interesting were going on. Learn how to calculate it, read it and avoid the classic misinterpretations.