Dice Probability Calculator
Find the exact chance of a target sum with identical fair dice.
Open toolPoisson Probability Calculator
Calculate P(X = k) for a Poisson event count. Nonnegative λ and whole k.
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Enter the inputs, then select Calculate.
Your result
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How Poisson Probability Calculator works
Calculate P(X = k) for a Poisson event count.
Nonnegative λ and whole k. Assumes independent events at a constant rate; returns a point probability, not a cumulative probability. Finite real inputs; output uses up to 12 significant digits. Floating-point results may be rounded.
How to use Poisson Probability Calculator
Follow the labelled inputs.
Enter expected event count λ
Replace the example with expected event count λ. The field labels specify the expected format and units.
Input and settings
Tool result
Run, review and save
Select Calculate. Review the calculated result, then copy it or download the result text.
Review the details
Examples and uses for Poisson Probability Calculator
Check the supplied example
The starting example produces 0.180447044315. Calculate P(X = k) for a Poisson event count.
Use your own inputs
Read the labels for expected event count λ and exact event count k. Nonnegative λ and whole k.
Record a reviewed result
Copy the calculated result into your notes. Keep the formula and assumptions with it if someone else needs to reproduce the calculation.
How to read the result
Read the units and assumptions with the output.
Calculate P(X = k) for a Poisson event count.
Nonnegative λ and whole k. Assumes independent events at a constant rate; returns a point probability, not a cumulative probability. Finite real inputs; output uses up to 12 significant digits. Floating-point results may be rounded.
Supported input and limits
Check the stated scope before you run it.
Nonnegative λ and whole k. Assumes independent events at a constant rate; returns a point probability, not a cumulative probability. Finite real inputs; output uses up to 12 significant digits. Floating-point results may be rounded.
The input stays in this browser. Copy result and Download save the same displayed text.
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Open toolPoisson Probability Calculator: common questions
Answers about using Poisson Probability Calculator and understanding its results.
What assumptions and input limits apply?
Nonnegative λ and whole k. Assumes independent events at a constant rate; returns a point probability, not a cumulative probability. Finite real inputs; output uses up to 12 significant digits. Floating-point results may be rounded.
How can I save the output?
Use Copy result to copy the displayed text, or Download to save it as a text file. The tool runs in your browser and does not require an account.
Calculate with your input
Check the calculated result, then copy or download it.