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Expected value calculator

Weight possible outcomes by their probabilities.

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Expected value calculator processes your input in this browser. Inputs and results are excluded from analytics. Recent tools save tool names, visit counts and last-visit times. Saved tools store only their names. Draft saving is optional and stays on this device; delete saved text with the draft controls. Loading text from a URL is optional and contacts that server; its URL and your IP address are visible to the server. An optional “Use in” action keeps a handoff in this tab. The next tool removes it on arrival and ignores it if more than a minute has passed.

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Spaces separate values; 1,000 is one value.

Answer

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Expected value = sum of each outcome × its probability. Variance weights squared distances from that expectation.

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Precision and calculation record
Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.
Saved scenario
Save the current answer, then change an input to compare. This clears when you leave.
Formula and assumptions
Outcomes must cover all mutually exclusive possibilities; their probabilities must add to one. Expected value is a long-run average, not a guaranteed result.
In a list, use spaces, new lines, semicolons, or commas followed by a space. A comma between groups of three digits is a thousands separator.
Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.
Scratch calculator
Use +, −, ×, ÷, parentheses and %. A percentage is divided by 100. This does not change the main tool.
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Links include your inputs and settings. Anyone with the link can see them, so leave out private text. Files and generated results are left out; random draws run again.
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Updated 
Using Expected value calculator
Expected value = sum of each outcome × its probability. Variance weights squared distances from that expectation.
Outcomes must cover all mutually exclusive possibilities; their probabilities must add to one. Expected value is a long-run average, not a guaranteed result.
Next: Standard error calculator
A worked example
With outcomes = -10, 20, probabilities = 0.6, 0.4, the expected value is 2.
Next: Statistics calculator
Before you use the result
Outcomes must cover all mutually exclusive possibilities; their probabilities must add to one. Expected value is a long-run average, not a guaranteed result.
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ToolOctopus. “Expected value calculator.” Updated 2026-09-26. https://tooloctopus.com/expected-value-calculator.
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