Board-game exploding dice calculator

Calculate resolved terminal-score probabilities within expansion and unresolved probability mass beyond expanded rolls with your own figures.

Your numbers

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

Use resolved terminal-score probabilities within expansion and unresolved probability mass beyond expanded rolls to compare changes to your inputs. The method and limits below explain the scope.

Examples

Examples

Try the starting example

Fair die sides
6
Explode on any face at/above this value
6
Maximum EXTRA rolls expanded before unresolved tail
2
At-least total score query
20
Resolved terminal-score probabilities within expansion
1: 0.166666666667; 2: 0.166666666667; 3: 0.166666666667; 4: 0.166666666667; 5: 0.166666666667; 7: 0.0277777777778; 8: 0.0277777777778; 9: 0.0277777777778; 10: 0.0277777777778; 11: 0.0277777777778; 13: 0.00462962962963; 14: 0.00462962962963; 15: 0.00462962962963; 16: 0.00462962962963; 17: 0.00462962962963
Unresolved probability mass beyond expanded rolls
0.00463
Unbounded expected score under stated repeating rule
4.2
Lower bound for queried at-least probability
0
Upper bound for queried at-least probability
0.00463

Try another scenario

Fair die sides
6
Explode on any face at/above this value
6
Maximum EXTRA rolls expanded before unresolved tail
0
At-least total score query
20
Resolved terminal-score probabilities within expansion
1: 0.166666666667; 2: 0.166666666667; 3: 0.166666666667; 4: 0.166666666667; 5: 0.166666666667
Unresolved probability mass beyond expanded rolls
0.166667
Unbounded expected score under stated repeating rule
4.2
Lower bound for queried at-least probability
0
Upper bound for queried at-least probability
0.166667
Calculation method

Calculation method

Resolved terminal-score probabilities within expansion

Sum fair-roll sequence counts ending on a nonexploding face, using a common exact denominator.

Unresolved probability mass beyond expanded rolls

Probability every expanded roll explodes; do not silently renormalize resolved scores.

Unbounded expected score under stated repeating rule

E(single fair roll)/(1−explosion probability), requiring at least one nonexploding face.

Lower bound for queried at-least probability

Resolved successes plus unresolved branches already at/above target, since future rolls are positive.

Upper bound for queried at-least probability

Resolved successes plus all unresolved mass; this is a rigorous bound, not a fitted tail.

Symbols and units
a
Fair die sides
b
Explode on any face at/above this value
c
Maximum EXTRA rolls expanded before unresolved tail
d
At-least total score 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 repeating additive exploding-die model with an explicitly expanded finite prefix and visible unresolved tail. Bounds concern one die chain, not a sum of several chains; no Monte Carlo sampling is used.
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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