What is the formula for converting odds to implied probability?

For decimal odds, divide 1 by the odds and multiply by 100. For fractional odds written a/b, divide b by (a + b) and multiply by 100. Decimal 26.0 and fractional 25/1 both give 3.85 per cent.

Why do implied probabilities in a golf market add up to more than 100 per cent?

Because the prices carry a built-in margin. A market summing to exactly 100 per cent would leave nothing for the layer, so the total always sits above it, and the excess is that margin rather than an error.

Does implied probability tell you a player's real chance of winning?

No. It tells you what the price is, expressed as a percentage, with the margin already inside it. A model's own probability for the same player is a separate estimate, and the two frequently disagree.

How do you work out implied probability for the place part of an each-way bet?

The place half is settled at a fraction of the win odds, commonly a fifth, so you convert the place price rather than the win price. Converting the win price and treating it as the place chance is the most common mistake.

← Blog · Method · 19 August 2026 · 6 min read

How do you convert golf odds into implied probability?

Divide one by the decimal odds and multiply by 100. That is the whole formula. The interesting part is what implied probability does not tell you, and why a golf outright market always adds up to more than 100 per cent.

By Doug Dinwiddie. Founder of ProPlace. Former DP World Tour caddie.

To convert decimal odds into implied probability, divide 1 by the odds and multiply by 100. Decimal odds of 26.0 give 1 / 26 = 0.0385, or 3.85 per cent. For fractional odds written a/b, implied probability is b / (a + b), multiplied by 100, so 25/1 is 1 / 26 again, the same 3.85 per cent.

ProPlace is a statistical research product, not a tipster service and not a bookmaker. 18+ | BeGambleAware.org

A conversion table for the prices you actually see in golf

Fractional	Decimal	Implied probability
Evens (1/1)	2.00	50.00%
4/1	5.00	20.00%
10/1	11.00	9.09%
16/1	17.00	5.88%
25/1	26.00	3.85%
40/1	41.00	2.44%
80/1	81.00	1.23%
150/1	151.00	0.66%

Golf outright prices sit at the long end of that table. A full field means most of the market is priced somewhere between roughly 1 and 5 per cent, and small differences in price down there move the implied number by very little in absolute terms while changing it a great deal in relative terms. 80/1 against 40/1 is a bit over one percentage point in absolute terms, and exactly half the implied chance.

Why the percentages add up to more than 100

Convert every player in a full outright field and add the results together, and the total comes out above 100 per cent. It has to. A market that summed to exactly 100 would leave the layer nothing at all, and the excess above 100 is the margin built into the prices.

That is precisely why implied probability is not the same thing as probability. It is the price with the margin already inside it, and a set of prices is a commercial position rather than a considered estimate of what each player is going to do.

The each-way complication

An each-way bet is two bets, and the place half is settled at a fraction of the win odds, so the implied probability of the win half and the implied probability of the place half are different numbers taken from the same price. Converting the win price and assuming it describes the place bet is the most common way people get this wrong. Each-way betting in golf, explained walks through the mechanics and the place terms.

What we use it for

The conversion is only useful as a comparison. A model produces its own probability for a player finishing high. The market produces an implied probability from its price. When the two disagree, that disagreement is the thing worth reading.

It is a difference of opinion rather than the discovery of a mistake. The market is not obliged to be wrong for the model to be interesting, and neither number is a forecast that anybody has to accept. We write about that gap in the gap between model probability and market consensus and in finding value on the PGA Tour with model versus consensus.

Doing it quickly in your head

For a price of X/1, the implied percentage is roughly 100 divided by (X + 1).
A useful anchor: 100/1 is just under 1 per cent, so anything longer than that is a sub-one-per-cent proposition however it is dressed up.

The conversion takes a second. The judgement about whether the resulting number means anything takes considerably longer, and that is the part worth spending time on.

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Doug Dinwiddie. Founder of ProPlace. Former DP World Tour caddie.

Frequently asked questions

What is the formula for converting odds to implied probability?: For decimal odds, divide 1 by the odds and multiply by 100. For fractional odds written a/b, divide b by (a + b) and multiply by 100. Decimal 26.0 and fractional 25/1 both give 3.85 per cent.
Why do implied probabilities in a golf market add up to more than 100 per cent?: Because the prices carry a built-in margin. A market summing to exactly 100 per cent would leave nothing for the layer, so the total always sits above it, and the excess is that margin rather than an error.
Does implied probability tell you a player's real chance of winning?: No. It tells you what the price is, expressed as a percentage, with the margin already inside it. A model's own probability for the same player is a separate estimate, and the two frequently disagree.
How do you work out implied probability for the place part of an each-way bet?: The place half is settled at a fraction of the win odds, commonly a fifth, so you convert the place price rather than the win price. Converting the win price and treating it as the place chance is the most common mistake.