Roulette bet expectation calculator

Calculate single-spin win probability and expected net result per spin with your own figures.

Your numbers

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

Choose the currency for these amounts. Changing it keeps your numbers and does not convert exchange rates.

Use single-spin win probability and expected net result per spin to compare changes to your inputs. The method and limits below explain the scope.

Examples

Examples

Try the starting example

Equally likely wheel pockets
37
Selected winning pockets
1
Stake per independent spin ($)
10
Net win payout per stake unit, excluding returned stake
35
Independent spins in scenario
100
Single-spin win probability
0.027027
Expected net result per spin ($)
-$0.27027
Single-spin net-result variance ($ squared)
3,408.035062
Expected net result across supplied spins ($)
-$27.03
Standard deviation across independent spins ($)
$583.78

Try another scenario

Equally likely wheel pockets
38
Selected winning pockets
1
Stake per independent spin ($)
10
Net win payout per stake unit, excluding returned stake
35
Independent spins in scenario
100
Single-spin win probability
0.026316
Expected net result per spin ($)
-$0.526316
Single-spin net-result variance ($ squared)
3,320.775623
Expected net result across supplied spins ($)
-$52.63
Standard deviation across independent spins ($)
$576.26
Calculation method

Calculation method

Single-spin win probability

Winning pockets/total pockets.

Expected net result per spin ($)

Stake×(p×net-win-multiple−(1−p)).

Single-spin net-result variance ($ squared)

Stake²×(net-win-multiple+1)²×p×(1−p), preserving square-dollar units.

Expected net result across supplied spins ($)

Spins×single-spin expectation.

Standard deviation across independent spins ($)

sqrt(spins×single-spin variance), assuming independent identical spins.

Symbols and units
a
Equally likely wheel pockets
b
Selected winning pockets
c
Stake per independent spin ($)
d
Net win payout per stake unit, excluding returned stake
e
Independent spins in scenario

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 supplied uniform-wheel/payout mathematical model, not actual casino terms, a profit forecast or a recommendation to gamble. Net payout excludes returned stake; loss is the stake. Variance uses squared currency units.
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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