Card draw probability calculator

Find hypergeometric probabilities for drawing exactly k marked cards without replacement.

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More inputs and assumptions

Answer

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Find hypergeometric probabilities for drawing exactly k marked cards without replacement.

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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

P(k) = C(marked,k) × C(unmarked,draws − k) ÷ C(total,draws). All cards are equally likely and draws are uniformly shuffled. No game strategy, replacement, pity counter or guaranteed pack distribution is assumed.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

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Using Card draw probability calculator

Find hypergeometric probabilities for drawing exactly k marked cards without replacement.

P(k) = C(marked,k) × C(unmarked,draws − k) ÷ C(total,draws). All cards are equally likely and draws are uniformly shuffled. No game strategy, replacement, pity counter or guaranteed pack distribution is assumed.

Next: Permutation combination calculator

A worked example

Example inputs: cards in population = 52, matching cards in population = 4, cards drawn without replacement = 5, matches wanted (k) = 1. Probability of exactly k matches (%) = 29.9473635608.

Before you use the result

P(k) = C(marked,k) × C(unmarked,draws − k) ÷ C(total,draws). All cards are equally likely and draws are uniformly shuffled. No game strategy, replacement, pity counter or guaranteed pack distribution is assumed.

Example results for cards in population

These examples use Matching cards in population: 4; Cards drawn without replacement: 5; Matches wanted (k): 1. They are reference calculations, not recommended settings.

Cards in populationProbability of exactly k matches (%)
2644.4816053512
5229.9473635608
10417.0557527132
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ToolOctopus. “Card draw probability calculator.” Updated 2026-09-26. https://tooloctopus.com/card-draw-probability-calculator.

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