How to use this betting tool
- Enter the requested market values and stake.
- Select the applicable line, method or settlement assumption.
- Choose Calculate and review the result, supporting figures and limitation note.
#101 · Odds Probability & Margin Tool
Positive EV Threshold Calculator
Find the minimum win probability needed to produce a chosen positive expected-value edge at given decimal odds. Calculations run locally in your browser. break-even point before risking a stake.
Calculator
Odds, probability and target edge%
%
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What this tool calculates
It solves p × decimal odds − 1 = target EV for p, then compares that threshold with your own estimated win probability.
Required probability = (1 + target EV) ÷ decimal odds; estimated EV = probability × odds − 1.
Expected value depends entirely on the quality of your probability estimate and does not guarantee a winning bet.
Worked example
At 2.10 odds and a 5% target edge, the required probability is 50.00%. A 52% estimate implies 9.20% EV.
| Decimal odds | 2.10 |
|---|---|
| Target EV | 5% |
| Required probability | 50.00% |
Tips and limitations
- Confirm the odds format and market settlement rules before relying on the result.
- Keep more precision in inputs; rounding is applied only for display.
- This calculator explains arithmetic and does not predict results or recommend a bet.
FAQ
What probability do I need for a 5% betting edge?
Divide 1.05 by the decimal odds and convert the result to a percentage.
How do I know if a bet is positive EV?
Your estimated probability multiplied by decimal odds must be greater than 1 after allowing for your target edge.
Does positive expected value mean the bet will win?
No. EV describes a long-run average under an assumed probability, not the outcome of one bet.
Should I use bookmaker implied probability for EV?
Not by itself. Bookmaker odds include margin and do not necessarily equal a fair probability.
Why is my required probability above 100%?
That can happen when the requested target return is impossible at the entered odds.
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Calculation reference
| Input | User-entered values |
|---|---|
| Method | Required probability = (1 + target EV) ÷ decimal odds; estimated EV = probability × odds − 1. |
| Output | Required probability |
| Processing | Browser only |
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