Implied probability calculator

What implied probability is

Implied probability turns betting odds into a percentage that shows how likely an outcome is, based on the odds given. It shows the bookmaker's view of an event's likelihood, and it lets you compare prices across different bookmakers.

The formulas

There is one formula for each odds format. Fractional odds are often called British odds, and they show the ratio of your stake that you win if the bet wins.

Decimal odds of 2.10 and fractional odds of 11/10 are the same price, and both imply 47.62%.

A worked example

Take the two sides of a match priced at decimal odds of 1.58 and 2.45. They imply 63.3% and 40.8%. Added together that is 104.1%, which is more than 100%. The odds include a margin, and implied probabilities are usually inflated so that the bookmaker profits.

What implied probability does not tell you

• It comes from the bookmaker's odds. Those don't always reflect true probabilities, and they are usually inflated so the bookmaker profits.
• Odds change by the minute, so an implied probability now can differ a minute later.
• Even an implied probability of 90% or more does not guarantee a return.

How this calculator works

• Odds can be typed as decimals (3.5), fractions (5/2) or evens. Fractions are converted to decimal first.
• Your estimate is optional. It must be above 0 and below 100.
• The comparison is the estimate less the implied probability, in percentage points. It states the gap and nothing more.
• Percentages are rounded to two decimal places.

Questions

What is implied probability?

Implied probability turns betting odds into a percentage that shows how likely an outcome is, based on the odds given. It shows the bookmaker's view of an event's likelihood.

How do I convert decimal odds to a percentage?

Divide 1 by the decimal odds and multiply by 100. Decimal odds of 2.10 imply 47.62%.

How do I convert fractional odds to a percentage?

Divide the denominator by the numerator plus the denominator, and multiply by 100. Odds of 11/10 imply 10 ÷ (11 + 10) × 100, which is 47.62%.

Is implied probability the real chance of winning?

Not always. Implied probabilities are based on bookmaker odds, and they don't always reflect true probabilities. They are usually inflated to make sure the bookmaker profits.

Does a high implied probability guarantee a win?

No. Even with an implied probability of 90% or more, a return is not guaranteed.

Why do the implied probabilities of a market add up to more than 100%?

Because the odds include the bookmaker's margin. Add up the implied probabilities of every outcome: the amount above 100% is the overround.