AbraCalc

Math & Statistics Calculators

24 tools in this collection — free, instant, and private in your browser.

Statistics and mathematics calculators help you make sense of data, quantify uncertainty, and solve counting problems without wading through tables or manual computation. They are useful for students learning probability and descriptive statistics, researchers checking sample sizes, and anyone who needs a quick numerical answer with a clear explanation of the method.

Descriptive statistics tools such as the Mean, Median, and Mode Calculator, Average Calculator, and Range and Midrange Calculator summarise a dataset in a few key numbers. For a deeper picture of spread and distribution, the Quartiles and IQR Calculator, Coefficient of Variation Calculator, and Percentile Rank Calculator extend the analysis. The Geometric Mean and Harmonic Mean calculators are appropriate when data represent rates, ratios, or proportions rather than simple additive quantities.

Probability tools cover both discrete and continuous distributions. The Binomial Probability Calculator handles yes/no trial scenarios with a fixed number of attempts, the Poisson Probability Calculator models rare events over a fixed interval, and the Normal Distribution Calculator gives cumulative and tail probabilities for bell-curve problems. For counting problems, the Permutation Calculator (nPr) answers ordered-selection questions and the Combination Calculator (nCr) answers unordered ones.

Inferential tools are available for common tasks in research and quality control. The Confidence Interval Calculator and Margin of Error Calculator quantify how precisely a sample reflects a population. The Correlation Coefficient Calculator measures linear association between two variables. The Population Growth Calculator applies exponential or logistic growth models.

Choose the tool that matches your type of data and your question. If you are summarising a list of numbers, start with the Mean/Median/Mode or Average tools. If you are testing a probability model, move to the distribution calculators. If you need to count arrangements, reach for the Permutation or Combination tool.

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ToolWhat it does
Average CalculatorCalculate the mean, sum, and count of a comma-separated list of numbers.
Average of Numbers CalculatorCalculate the arithmetic mean (average) of up to five numbers. See the sum and count as well.
Binomial Probability CalculatorCalculate the exact binomial probability P(X = k) for n trials with probability p.
Coefficient of Variation CalculatorCalculate the coefficient of variation (CV) — standard deviation as a percentage of the mean.
Combination Calculator (nCr)Calculate the number of combinations of n items taken r at a time (nCr).
Confidence Interval CalculatorCalculate the confidence interval for a population mean from sample data.
Correlation Coefficient CalculatorCalculate the Pearson correlation coefficient (r) between two lists of numbers.
Geometric Mean CalculatorCalculate the geometric mean of a list of positive numbers.
Harmonic Mean CalculatorCalculate the harmonic mean of a list of positive numbers.
Margin of Error CalculatorCalculate the margin of error for a survey proportion given sample size and confidence level.
Mean, Median, and Mode CalculatorCalculate the mean, median, and mode of a list of numbers.
Normal Distribution CalculatorCalculate the cumulative probability Φ(z) for a standard normal distribution.
Percentile Rank CalculatorFind the percentile rank of a value within a dataset.
Permutation Calculator (nPr)Calculate the number of permutations of n items taken r at a time (nPr).
Poisson Probability CalculatorCalculate the Poisson probability P(X = k) for a given rate λ and count k.
Population Growth CalculatorModel continuous population growth using P(t) = P₀·e^(rt). Enter starting population, growth rate and years to see final population, doubling time and a growth chart.
Quartiles and IQR CalculatorCalculate Q1, Q2 (median), Q3, and the interquartile range (IQR) from a list of numbers.
Range and Midrange CalculatorCalculate the range and midrange of a list of numbers.
Sample Size CalculatorCalculate the required sample size for estimating a population proportion.
Standard Deviation CalculatorCalculate sample and population standard deviation from a list of numbers.
Standard Error CalculatorCalculate the standard error of the mean (SEM) from the standard deviation and sample size.
Variance CalculatorCalculate sample and population variance from a list of numbers.
Weighted Mean CalculatorCalculate the weighted mean (weighted average) from values and their weights.
Z-Score CalculatorCalculate the z-score (standard score) of a data point given the mean and standard deviation.

Frequently asked questions

What is the difference between the Average Calculator and the Mean, Median, and Mode Calculator?
The Average Calculator is streamlined for quickly finding the arithmetic mean of a set of numbers. The Mean, Median, and Mode Calculator computes all three measures of central tendency together, which is more useful when you want a complete picture of where the centre of your data lies.
When should I use the Geometric Mean instead of the regular average?
Use the geometric mean when your values represent multiplicative quantities such as growth rates, percentage changes, or financial returns. Averaging those values arithmetically gives a misleading result; the geometric mean correctly captures the compound effect.
How do I enter data into these calculators?
Most tools accept a comma-separated or space-separated list of numbers pasted directly into a text field. Some tools, such as the Confidence Interval Calculator, ask for summary statistics like sample size, mean, and standard deviation instead of raw data.