Betting Odds Calculator
Enter any fractional odds to calculate the probability, decimal equivalent, and potential winnings.
Disclosure: Tablet Betting is operated by Winners Media Limited and may receive compensation from listed brands. Read full disclosure.
Common Betting Odds
These are the standard fractional odds used by UK bookmakers. Click any to see the full calculation.
Odds On (shorter than evens)
Evens to 3/1
Medium Odds (4/1 to 11/1)
Long Odds (12/1 and above)
How Fractional Odds Work
Fractional odds like 5/1 (said “five to one”) tell you the profit relative to your stake. At 5/1, you win 5 for every 1 you bet. A £10 bet at 5/1 wins £50 profit plus your £10 stake back, so £60 total.
Odds on bets like 1/2 mean you risk more than you win. A £10 bet at 1/2 wins £5 profit. These are short-priced favourites where the bookmaker thinks the outcome is likely.
For a full guide to odds formats including decimal and American odds, see our betting odds explained page.
Reading horse racing odds
Racing is where fractional odds still do most of the work. A racecard prints prices like 7/2 or 11/4 rather than decimals, and the shape of the market tells you as much as any individual price. The shortest price in the race is the favourite. If two runners share the shortest price they are joint favourites, and a field with no clear favourite usually means the race is genuinely open rather than that the bookmakers have not made their minds up.
Prices move between the morning and the off. An early price is the bookmaker’s first opinion, taken before most of the money has gone on. Starting price, often shown as SP, is the price returned at the moment the race begins. A horse that shortens from 6/1 to 7/2 has been backed heavily; one that drifts from 6/1 to 10/1 has not. Neither movement tells you the result, but it does tell you where the money went.
Working out what a racing bet returns
The arithmetic is the same as any other sport. Divide the first number by the second to get the profit per unit staked, then add the stake back to get the total return. At 7/2, a 10 stake returns 35 profit plus the 10 back, so 45 in total. The calculator above does this for any fraction, including the awkward ones a racecard throws up like 8/13 or 4/11.
Two racing-specific wrinkles catch people out.
The first is each way. An each way bet is two bets of equal size: one for the win and one for a place. The place part is settled at a fraction of the win odds, commonly a fifth or a quarter depending on the number of runners and the type of race. So a 10 each way bet costs 20, not 10, and the place return is calculated on the reduced fraction rather than the full price.
The second is a withdrawn runner. If a horse is pulled out after the market has formed, the remaining prices are too generous, because the money that was on the non-runner has nowhere to go. Rather than reprice every bet, the industry applies a fixed deduction to winning bets struck at the old prices. That is Rule 4, and the amount taken off depends on the withdrawn horse’s price at the time. Our guide to Rule 4 deductions sets out the full table.
Why the prices never add up to 100 per cent
Convert every price in a race to its implied probability and add them together. The total always comes to more than 100 per cent. That excess is the overround, sometimes called the margin, and it is how a bookmaker makes money whatever wins.
The maths is straightforward. Implied probability is 1 divided by the decimal price, or in fractional terms the denominator divided by the sum of both numbers. A price of 3/1 implies 25 per cent. A price of evens implies 50 per cent. Work through a card, total the percentages, and subtract 100. A competitive two-runner market might come to 104 or 105 per cent. A twenty-runner handicap can run well past 120 per cent, because every extra runner is another chance to build margin in.
This matters for a practical reason rather than an academic one. The overround is the clearest way to compare one bookmaker with another on the same race. Two firms showing different prices on the same horse are both making a margin; the one with the lower total is taking less out of the race. Big televised races carry the tightest margins because that is where the competition is. Small midweek cards carry the widest.
Odds and probability are not predictions
An implied probability is derived from a price, and that price is set to balance a book, not to forecast a result. A horse at 4/1 is not guaranteed to win one race in five. What the price tells you is the return on offer if it does win, and roughly how the market rates its chance after the margin has been added. Treat the percentage as a translation of the price, not a tip.
If you want the full breakdown of fractional, decimal and American formats, our betting odds explained guide works through each one. For combining several selections into one bet, see the accumulators guide.
