What is implied probability in betting?

100 divided by decimal odds. Includes bookmaker margin so true probability is always lower.

A value bet is where bookmaker odds imply lower probability than the true probability. Positive edge = good value.

How do I calculate betting edge?

Edge (%) = (True probability × Decimal odds - 1) × 100. Example: 50% probability at 2.50 = +25% edge.

Is this calculator useful for matched betting?

For pure matched betting, no. Probability analysis is most useful for value betting where you identify underpriced selections.

Percentage Calculator - Fast, Free and Simple

About

Use this calculator to answer common percentage questions in seconds, like finding a discount, working out a share of a total, or measuring how much a value has moved up or down. It is also useful for quick sanity checks when comparing prices, margins, or performance. SharkBetting builds practical calculators that help you make clearer, more informed decisions.

FAQ

A percentage tells you how many parts out of 100 something represents. It is a simple way to describe a share, a rate, or a change. For example, 25 out of 100 equals 25%.

Most of the time you can use: (part ÷ whole) × 100. Example: if 20 out of 50 apples are red, 20 ÷ 50 = 0.4, and 0.4 × 100 = 40%.

Percentages make it easy to compare things on the same scale, whether you are looking at discounts, fees, growth, or performance over time. They are also common in betting and trading where you want to think in rates and risk rather than raw numbers.

Use: ((new − old) ÷ old) × 100. Example: from 80 to 100 is ((100 − 80) ÷ 80) × 100 = 25%.

A betting percentage calculator converts between odds, implied probability, and edge percentage. It shows whether a bookmaker price represents positive expected value by comparing the implied probability in the odds against your true probability estimate.

Implied Probability vs True Probability

Implied probability formula

100 ÷ Decimal odds. Example: 2.50 → 40% implied probability

Edge formula

Edge (%) = (True probability × Decimal odds − 1) × 100

50% true prob at 2.50 = (0.50 × 2.50 − 1) × 100 = +25% edge. Positive = good value bet.

Common Mistakes with Probability

✕
Confusing implied with true probability. Implied probability includes the bookmaker margin (vig). It is always higher than the true probability for the same selection.
✕
Treating a high implied probability as a good bet. 90% implied at 1.11 may be worse value than 40% implied at 2.50, depending on true probability in each case.