Decimal prices of 2.00 and 4.00 have reciprocals of 50% and 25%. These are often called implied probabilities. They express a price as a percentage; they do not establish the objective chance of a match outcome.
Start with one formula
Reciprocal percentage = 1 / decimal price × 100
| Price | Calculation | Percentage |
|---|---|---|
| 2.00 | 1 / 2.00 | 50% |
| 2.50 | 1 / 2.50 | 40% |
| 4.00 | 1 / 4.00 | 25% |
These are separate fictional examples, not outcomes to add together for one fixture. Compare prices only when the outcome and settlement basis match.
Why a complete set can exceed 100%
Now imagine a single fictional market with three mutually exclusive outcomes covering all possibilities: A at 2.00, B at 3.50 and C at 4.00.
Their reciprocals are 50%, about 28.57% and 25%. The unrounded sum is about 103.57%. Its excess over 100% is about 3.57 percentage points. That overround is not a direct measurement of realised profit.
A proportional calculation
Dividing each reciprocal by the unrounded total produces approximately 48.28%, 27.59% and 24.14%. Display rounding makes these add to 100.01%.
This method scales every outcome proportionally. It is one comparison method, not proof of the true probabilities or the only possible adjustment.
Percent versus percentage points
A change from 50% to 55% is 5 percentage points. Relative to the initial 50%, the increase is 5 / 50 = 10%. Specify which measure you mean.
Before comparing numbers
Check the fixture, outcome, observation time and settlement rules. Do not mix in-play with pre-match observations or label a simple conversion as an established real-world chance.
All values here are educational examples, not recommendations for a match or a return. Continue with reading price movements.
▶
▶
▶