How betting odds work

Decimal odds are the standard format at Nigerian bookmakers. A decimal price is the total return for every ₦1 staked, with the stake included. Multiply your stake by the odds and you have what a winning bet pays back. Subtract the stake and you have the profit.

Odds of exactly 2.00 double your money and are called evens. Any price below 2.00 pays a profit smaller than the stake, which is why short prices need a large stake to win a small amount: ₦5,000 at 1.25 returns ₦6,250, a profit of ₦1,250.

Every price is also a statement about chance. Divide 100 by the decimal odds and you get the implied probability: how often the outcome would have to happen for the bet to break even over the long run. Odds of 2.10 imply 47.6%. Odds of 4.00 imply 25.0%.

The shorter the price, the more likely the bookmaker rates the outcome and the less it pays. Treat implied probability as the bookmaker’s price, not as a forecast: it has the bookmaker’s cut built in, as the next section shows.

A football match has three results: home win, draw, away win. Exactly one of them happens, so their true probabilities add up to 100%. The implied probabilities of a bookmaker’s three prices always add up to more. The amount above 100% is the margin, also called the overround. It is how a bookmaker earns money whichever result comes in.

Put another way, this market pays back 95.4% of the money staked on it (100 ÷ 104.8%) and the bookmaker keeps the rest. With the margin taken out in proportion, the same three prices would be 2.20, 3.56 and 3.77. No bookmaker offers those. They are the yardstick a real price is measured against.

Bookmakers rarely show the same prices for one match. Each sets its own margin, each has its own view of the teams, and each moves its prices as money comes in on one side. A bookmaker may also run a thin margin on the big leagues and a wider one on smaller competitions.

On a ₦5,000 home win the gap is ₦250: ₦10,500 against ₦10,250. These are worked examples of quoted prices, not measurements taken from the listed operators. Odds carry 20% of the editorial overall in the Betbook Table; how we rate betting sites explains the method and its limits.

Sites built for British or American customers show the same price in other formats. Fractional odds give the profit against the stake: 3/2 means ₦3 of profit for every ₦2 staked, which is 2.50 in decimal. American odds use a sign. A plus figure is the profit on a stake of 100, so +150 is also 2.50. A minus figure is the stake needed to win 100, so −200 is 1.50.

The converter prints the exact fraction. British bookmakers write some fractions in a traditional form, such as 6/4 for 3/2; the price is the same. Whatever the format, the decimal figure is the one to calculate with.

Punters use the word value for a price that implies a lower probability than the one they believe is true. If you think an outcome happens 45% of the time and the odds are 2.50, which imply 40.0%, then by your own estimate the price is in your favour.

The weak point is the estimate. Nobody knows the true probability of a football result. The bookmaker’s price already reflects a great deal of information, and the margin works against you from the first bet. A bet that looks like value can lose, and so can a long run of them. Value is a way to compare a price with your own opinion. It is not a method that produces profit, and no tipster, site or formula can promise one.

An accumulator multiplies the odds of every selection together, and every selection has to win. Four selections at 1.90 multiply to 13.0321 (1.90 × 1.90 × 1.90 × 1.90), so ₦1,000 returns ₦13,032 if all four come in.

The margins multiply too. Take a market with two equally likely outcomes. The fair price for each is 2.00; a bookmaker offers 1.90 on both, which pays 95.0% of the fair return. In an accumulator of four such legs that share applies four times: 95.0% × 95.0% × 95.0% × 95.0% = 81.5%. The same ₦1,000 at fair prices would return ₦16,000.

This is why accumulators pay large sums and lose often, and why the price on each leg matters more than a bonus added on top. More on this is in accumulator betting: how accas work. Each bookmaker’s odds score is shown in the table of Nigeria betting sites.

1. Multiply the stake by the decimal odds to get the total return.
2. Divide 100 by the odds to get the implied probability.
3. Add the implied probabilities of every outcome in a market. What is above 100 is the margin.
4. Look at the same market at more than one site: the prices, and the margins, differ.
5. In an accumulator, expect the margin on every leg to multiply.

Apply decimal prices with the accumulator return calculator. The double-chance explanation and draw-no-bet guide show why a different settlement condition changes the price.

For a price that moves during submission, read Odds Changed Before Your Bet Was Accepted.