Fractional or decimal? Make sense of the odds.

Two formats, one price

Fractional and decimal odds are different ways to express a betting price. Changing the display format does not improve the value of the price you receive.

Fractional odds

At fractional odds of 3/1, a winning £10 stake produces £30 profit plus the returned £10 stake: a £40 total return. A losing bet normally loses the £10 stake. This example is for a standard win bet and excludes special offers and deductions.

Decimal odds

The same price is 4.00 in decimal odds. Multiply the stake by 4.00 to calculate the total return on a winning bet: £10 × 4.00 = £40. The stake is included, so the profit is £30.

Converting the formats

For a fraction a/b, decimal odds are a divided by b, plus one. For example, 5/2 becomes 3.50. To go the other way, subtract one from the decimal odds and express the result as a fraction.

Odds-on prices and evens

A fraction smaller than one describes less profit than the amount staked if the bet wins. At 1/2, a £10 winning stake produces £5 profit and a £15 total return. The equivalent decimal price is 1.50. Evens is 1/1, or 2.00: £10 returns £20 in total, including the stake.

These are arithmetic examples using an ordinary cash stake. They do not recommend a stake size or make a shorter-priced selection safe. An odds-on bet can still lose the whole stake.

A quick conversion checklist

• 1/4 is 1.25: a winning £8 stake returns £10, of which £2 is profit.
• 4/5 is 1.80: a winning £10 stake returns £18, of which £8 is profit.
• 5/2 is 3.50: a winning £4 stake returns £14, of which £10 is profit.
• 7/2 is 4.50: a winning £2 stake returns £9, of which £7 is profit.

For decimal odds d and cash stake s, total winning return is s × d. Net profit is s × (d − 1). Subtract the stake once, not twice. A displayed potential return is conditional on the bet winning and on any applicable settlement adjustments.

Rounding can hide part of a price

Some fractions produce recurring decimals. For example, 10/3 converts to 4.3333… rather than exactly 4.33. A £3 winning stake at the exact fractional price returns £13; multiplying a rounded display of 4.33 gives £12.99.

Paddy Power's published explanation says its displayed decimals are rounded to two places while returns use the underlying odds and are paid to the nearest penny. Check the accepted price and the rounding terms of your own operator. A tiny display difference is not evidence that changing the format improves the bet.

Implied probability is not a prediction

The mathematical implied probability is 1 divided by decimal odds, multiplied by 100 for a percentage. The equivalent fractional formula is b ÷ (a + b) × 100. Thus 3/1, or 4.00, implies 25%; 1/2, or 1.50, implies about 66.67%.

These figures describe the price, not a measured chance of the selection winning. In a simplified two-outcome market with both outcomes at 1.80, each implies about 55.56%, for a total of about 111.11%. The amount above 100% is called the overround. This example illustrates a pricing margin; it does not predict the bookmaker's eventual profit or the true probability of either outcome.

What odds do not tell you

Odds do not guarantee an outcome. A quoted price is not an independent assessment of the true chance of winning. Sportsbook prices typically include a margin. An exchange may apply commission, so its terms can change the net result.

Read the market rules

Before placing a bet, check exactly what the selection covers and how it settles. Extra time, a withdrawal, a postponement or a dead heat may be handled differently between markets. Check the rules on the site you use.

A void selection can change the calculation entirely. In bet365's GB help, an ordinary void single returns the stake, while an accumulator with a void selection is settled using the remaining selections. Our void bets and settlement guide explains the difference with a worked example and product-specific exceptions.

Each-way bets also need separate win and place calculations, including the advertised place fraction and number of places. Free bets, deductions and exchange commission can change the result. Do not use a standard cash win-bet formula as a promise of what any of those products will pay.

Set a limit first

Understanding odds is useful, but it cannot remove the risk of losing money. Decide what you can afford to lose before betting, and avoid chasing losses. Read about deposit limits, time-outs and self-exclusion, or visit our support page if gambling is affecting you.

Does decimal 4.00 mean four pounds profit per pound?

No. It means a £4 total return for a winning £1 cash stake before any relevant adjustments. That includes the £1 stake, leaving £3 profit.

Can I compare two prices just by converting them?

Only if they cover the same outcome on the same settlement basis. A price for the result after normal time is not interchangeable with a price to qualify for the next round. Check the market name and terms before comparing the numbers.

For a researched operator example, our Paddy Power review links its current betting rules and explains the limits of this desk-based review.