Guide

Betting odds explained

Updated 12 November 2026 · 4 min read

Betting odds are a price: they say what a winning bet returns and, turned round, how likely the bookmaker thinks the result is. The same price can be written three ways: decimal (2.50), fractional (3/2) and American (+150). With decimal odds you multiply your stake by the price to get your total return, so 10 at 2.50 returns 25, a profit of 15.

What odds tell you

Odds are the price of a bet. A bookmaker quotes a number for each possible result, and that number says two things at once: how much a winning bet pays, and how likely the bookmaker thinks the result is. The shorter the price, the likelier the result; the longer the price, the less likely it is.

A price of 2.00 pays back double your stake if you win. It is the price of a coin toss: the bookmaker is saying the result is about 50 % likely. A price of 5.00 pays five times your stake and says the result is about 20 % likely.

The three odds formats

Decimal, fractional and American odds are three ways of writing the same price. Which one you see depends on where you are: decimal is used across Europe, Africa, Australia and Canada, fractional is the traditional British and Irish style, and American odds are used in the United States. The table shows the same prices in all three, with the chance each one implies.

The same price in three formats
Decimal	Fractional	American	Implied chance
1.25	1/4	-400	80 %
1.50	1/2	-200	66.7 %
1.91	10/11	-110	52.4 %
2.00	1/1 (evens)	+100	50 %
2.50	3/2	+150	40 %
3.00	2/1	+200	33.3 %
5.00	4/1	+400	20 %

Decimal odds

Decimal odds are the simplest to use. Multiply your stake by the odds to get your total return, stake included. The profit is the return less the stake.

Return = stake × odds.
Profit = stake × (odds - 1).
10 at 2.50 returns 25: a profit of 15.

Decimal odds are never below 1.00. A price of 1.00 would return only your own stake; the shortest prices bookmakers offer sit just above it.

Fractional odds

Fractional odds show the profit compared with the stake. 3/2 (said "three to two") means you win 3 for every 2 you stake. Your total return is the profit plus your stake back.

Profit = stake × (top ÷ bottom).
5/2 on a stake of 10: a profit of 25 and a total return of 35.
To get decimal odds, divide the fraction and add 1: 5/2 is 2.5, plus 1 is 3.50.

"Evens" means 1/1: you win what you stake. A price such as 1/4 is odds-on, which means the result is favoured: you must stake 4 to win 1.

American odds

American odds are written with a plus or a minus sign, and the number is measured against 100.

A plus number (+150) is the profit on a stake of 100: 100 at +150 wins 150. In decimal that is 1 + 150 ÷ 100 = 2.50.
A minus number (-150) is the stake needed to win 100: staking 150 wins 100. In decimal that is 1 + 100 ÷ 150 = 1.67.

Minus numbers mark the favourite and plus numbers the underdog. -110, which you will see on many US point-spread and total bets, is about 1.91 in decimal, which implies a chance of 52.4 %.

Turning odds into a chance

A price implies a chance: divide 1 by the decimal odds. At 2.50 the implied chance is 1 ÷ 2.50 = 40 %. At 1.25 it is 80 %. This is the number to set beside your own view of the result: if you think a result is likelier than the price implies, the price is worth a look. Implied probability and fair price shows how.

A bookmaker's prices for all the results of a match add up to more than 100 %. The extra is the bookmaker's margin. How to read football odds works an example.

Questions

What do odds of 2.50 mean?

Decimal odds of 2.50 mean a winning bet returns 2.50 for every 1 staked: a stake of 10 returns 25, a profit of 15. The price implies a chance of 40 %, because 1 divided by 2.50 is 0.40.

Which odds format is best?

None: they are the same price written three ways, so the format changes nothing about what a bet pays. Decimal is the easiest to calculate with, which is why most betting tools, ours included, work in it. Dawn Odds can show prices in whichever format you prefer.

What does +150 mean in betting?

It is an American price: a winning bet of 100 profits 150. In decimal odds that is 2.50, and it implies a chance of 40 %.

What does -110 mean?

You must stake 110 to win 100, which is decimal odds of about 1.91 and an implied chance of 52.4 %. It is the usual price on both sides of an even US bet, and the two sides' implied chances add up to 104.8 %: the extra is the bookmaker's margin.

How do I convert fractional odds to decimal?

Divide the top by the bottom and add 1. 5/2 is 2.5 + 1 = 3.50, and 1/4 is 0.25 + 1 = 1.25.