Deck draw target probability calculator

Calculate probability of at least queried target count and target-card-count distribution with your own figures.

Your numbers

Use the units shown. Results update as you change valid inputs.

Use probability of at least queried target count and target-card-count distribution to compare changes to your inputs. The method and limits below explain the scope.

Examples

Examples

Try the starting example

Remaining deck/population size
10
Target cards remaining
3
Cards drawn without replacement
4
At-least target count to query
2
Probability of at least queried target count
0.333333
Target-card-count distribution
0: 0.166666666667; 1: 0.5; 2: 0.3; 3: 0.0333333333333; 4: 0
Expected target-card count
1.2
Target-card-count variance
0.56

Try another scenario

Remaining deck/population size
10
Target cards remaining
3
Cards drawn without replacement
4
At-least target count to query
3
Probability of at least queried target count
0.033333
Target-card-count distribution
0: 0.166666666667; 1: 0.5; 2: 0.3; 3: 0.0333333333333; 4: 0
Expected target-card count
1.2
Target-card-count variance
0.56
Calculation method

Calculation method

Probability of at least queried target count

Sum hypergeometric counts at/above the queried count.

Target-card-count distribution

choose(targets,k)×choose(nontargets,draw−k)/choose(population,draw), including zero-probability counts.

Expected target-card count

draw×targets/population.

Target-card-count variance

Finite-population variance, obtained from exact first and second count moments.

Symbols and units
a
Remaining deck/population size
b
Target cards remaining
c
Cards drawn without replacement
d
At-least target count to query

Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.

Assumptions & limits

Assumptions & limits

  • A uniform unordered draw without replacement from a supplied finite population. It does not infer card identities, shuffle quality, betting choices or an actual game’s hidden state.
Are these inputs private?

These calculations run in your browser. A shared link contains the values you choose to share. Only questions submitted to the separate AI finder are sent to OpenAI.

Further reading

OpenStax: finite probability and sampling without replacement; rules are explicit in each worksheet ↗

Background reading; this does not imply endorsement or independent review of SumFizz.

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