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Expected value calculator

Compute the expected value from a list of outcomes and their probabilities.

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Enter Outcomes (comma-separated), Probabilities (comma-separated) and the Expected value calculator works out Expected value straight away. For instance, with Outcomes (comma-separated) = 10, 20, -5 and Probabilities (comma-separated) = 0.5, 0.3, 0.2 it returns Expected value = 10.

How to use it

  1. Enter your values: Outcomes (comma-separated), Probabilities (comma-separated).
  2. Read the result instantly: Expected value.

Frequently asked questions

What does the Expected value calculator actually compute?

It takes Outcomes (comma-separated) and Probabilities (comma-separated) and derives Expected value from them. The calculation is live as you type, so the result updates on every change.

What information do I need to provide?

2 values: Outcomes (comma-separated) and Probabilities (comma-separated). Nothing else is required — no account, no file upload.

Can you show a worked example?

With Outcomes (comma-separated) = 10, 20, -5 and Probabilities (comma-separated) = 0.5, 0.3, 0.2, the calculator returns Expected value = 10. Those figures come from running this exact tool, so you can reproduce them by entering the same values.

What happens if I enter larger values?

It moves a lot. Using Outcomes (comma-separated) = 10, 21, -5 and Probabilities (comma-separated) = 0.5, 0.32, 0.22 instead, Expected value goes from 10 to 10.62 — which is why it is worth testing a few scenarios rather than trusting a single figure.

What does it give for smaller values?

Scaled down to Outcomes (comma-separated) = 10, 20 and Probabilities (comma-separated) = 0.5, 0.3, Expected value comes out at 11. The relationship is worth checking at both ends before you rely on a single result.

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.

What is the difference between the Expected value calculator and the p-Value Calculator?

This one returns Expected value; the p-Value Calculator returns Result. That is the whole difference — open the one whose figure you need.

Is there a tool for the next step?

Coefficient of variation calculator is the closest one after this: Compute the coefficient of variation (CV) of a dataset — its relative variability.

What else is worth having open alongside it?

Correlation coefficient calculator and Geometric mean calculator — they come up in the same task often enough to be worth a second tab.

Further reading

All guides →
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.ExplainerWhat Is a Percentile? The 90th Percentile ExplainedA percentile tells you where a value ranks within a group. Learn what the 90th percentile really means and why a percentile is not the same as a percentage.How-toHow to Calculate a Weighted AverageA weighted average gives some values more influence than others. Learn the Σ(w·x) / Σw formula with grade and portfolio examples you can follow step by step.How-toHow to Find a Cube Root by HandA step-by-step guide to finding a cube root by estimation and refinement — plus how it differs from a square root and when a value stays irrational.ExplainerHow Exponents Work: Powers and the Laws of ExponentsAn exponent is repeated multiplication. Learn the laws of exponents, what negative and fractional powers mean, and why anything to the zero is one.