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p-Value Calculator

Turns a z, t, χ² or F statistic into a p-value, one- or two-tailed, with the density curve and the rejected area drawn. The reading in words is included, because a p-value is the most misread number in statistics.

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Open p-Value Calculator and you get an answer straight away, with no account to create. Its place is under Statistics & probability; Expected value calculator and Absolute Value Equation Solver answer the questions closest to this one.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What does p-Value Calculator do?

Turns a z, t, χ² or F statistic into a p-value, one- or two-tailed, with the density curve and the rejected area drawn. The reading in words is included, because a p-value is the most misread number in statistics.

When would I actually use this?

Summarising a dataset before drawing conclusions from it, checking whether a difference between two groups is real, and putting an interval around an estimate.

What is the most common mistake?

Reading a p-value as the probability that the hypothesis is wrong. It is the probability of seeing data at least this extreme if the null were true — a different statement, and a much weaker one.

How is p-Value Calculator different from Expected value calculator?

They sit next to each other but answer different questions: Expected value calculator is the one to open when you need it to compute the expected value from a list of outcomes and their probabilities. Pick whichever matches what you're starting from — both are free.

Is there a tool for the next step?

Absolute Value Equation Solver is the closest one after this: Solve absolute-value equations like |x+3| = 5, 3|x+2| = 12 or |x+1| = |x−3| with step-by-step case analysis and exact solutions.

What else is worth having open alongside it?

Absolute Value Inequality Solver and ANOVA Calculator (One-Way) — they come up in the same task often enough to be worth a second tab.

Where do the figures come from?

Distributions and test statistics are computed from their standard definitions, not from a lookup table, so results carry more digits than a printed table would. The assumptions each test makes are stated with it.

Further reading

All guides →
ExplainerProbability Basics, With ExamplesProbability measures how likely something is, from 0 to 1. Here's the basic idea, how to combine events with AND and OR, and the complement.ExplainerA 1 % Drop Rate Does Not Mean One Hundred RunsAt 1 %, a hundred attempts give you 63.4 % — not certainty. Ninety per cent takes 230 attempts and ninety-nine takes 459, and more than a third of players are still empty-handed at a hundred.ExplainerWhat Is a Z-Score? Standard Deviations Above the MeanA z-score is z = (x − μ) / σ — how many standard deviations a value sits from the mean. Learn how to compute it, read the standard normal curve, and turn it into a percentile.ExplainerMean, Median and Mode: What's the Difference?Mean, median and mode all describe the 'middle' of your data — but answer different questions. Here's what each means, with examples and when to use which.ExplainerGeometric vs Arithmetic Mean: Which to UseThe arithmetic mean adds and divides; the geometric mean multiplies and takes a root. Learn which fits growth rates, ratios, and averages.How-toHow to Calculate Standard Deviation (Step by Step)Standard deviation measures how spread out your data is. Here's the formula, a worked example, and the difference between population and sample.