Type odds into any box and the other three update as you go, along with what your stake returns. Fractional, decimal, moneyline and implied probability.
7/4, 2.75, +175 and 36.36% are the same bet. The format is a habit rather than a difference: UK bookmakers grew up on fractions, exchanges quote nothing but decimals, and American sportsbooks count in hundreds. Work in whichever one you think in and let the converter handle the rest.
| Format | This bet | What it's telling you |
|---|---|---|
| Fractional | 7/4 | £7 profit for every £4 staked |
| Decimal | 2.75 | £1 comes back as £2.75 |
| Moneyline | +175 | A 100 stake wins 175 |
| Probability | 36.36% | The price says roughly one time in three |
Read it as profit per stake: 7/4 pays seven for every four you put on. What trips people up is the flip at evens. Once a selection is odds-on the larger number moves to the right, so 2/5 means risking £5 to make £2. Larger figure first means the selection is against you, larger figure second means it's favourite, and 1/1 in the middle is evens.
Your stake comes back on top of the fraction. A £10 bet at 7/4 makes £17.50 and hands your tenner back, so £27.50 hits the account. Fractions quote the profit only, which is the whole reason a fraction looks smaller than the decimal sitting next to it.
Decimal is the entire return with your stake already in it, so there's one sum and no adding back. £10 at 2.75 returns £27.50 and you're done.
It's also the only format you can compare at speed. Is 6/4 better than 13/8? You have to stop and think. Written as 2.50 against 2.62, you already know. That's why exchanges quote nothing else, why every lay stake formula on this site expects decimal, and why the display setting buried in your bookmaker account is worth the two minutes.
American odds, built around a stake of 100. A plus number is the profit on that 100, so +175 wins 175. A minus number is what you have to risk to make 100, so -140 means putting up 140 to win a hundred. The sign flips at evens, which is +100, and like fractions it quotes profit rather than the full return.
You'll mostly meet it on US sports, where both sides of a two-way market are usually priced at -110. That symmetry isn't generosity, and the next section is what it costs.
Divide 100 by the decimal odds and you get the implied probability, which is the chance the price is quoting. 2.75 implies 36.36%. 1.40 implies 71.43%.
Add up a whole market and it comes to more than 100%, and the surplus is the bookmaker's cut. Take a match priced 2.20, 3.40 and 3.30:
| Outcome | Decimal | Implied probability |
|---|---|---|
| Home | 2.20 | 45.45% |
| Draw | 3.40 | 29.41% |
| Away | 3.30 | 30.30% |
| Total | 105.17% |
Nothing has three possible outcomes and a 105% chance of happening. The extra 5.17% is the overround, also called the margin or the vig, and it's the bookmaker's edge written into every price on the board. Bet into that market at random and you lose about a fiver in every hundred over time, with no skill involved either way.
Those -110 American lines work out the same. Two sides at -110 is 52.38% each, 104.76% in total. Same trick, different notation.
Add a market up before you bet into it. Football match odds usually land somewhere between 102% and 105%, which is tight. A twenty-runner handicap can pass 120%, which is not the same game at all, whatever the racing post says about the favourite. And if a book ever totals under 100%, somebody has mispriced something. That's an arb, and it rarely survives the afternoon.
A betting exchange sits at the other end of this. There's no margin in the price, just commission on winnings, so an exchange book hovers near 100%. That's what makes exchange odds the reference point for whether a bookmaker's price is any good, and it's the number our oddsmatcher compares everything against.
Every price on the standard bookmaker ladder, with what a £10 stake comes back as. Type in the box to filter it.
| Fractional | Decimal | £10 returns | Probability | Moneyline |
|---|---|---|---|---|
| 1/5000 | 1.00 | £10.00 | 99.98% | -500000 |
| 1/1000 | 1.00 | £10.01 | 99.90% | -100000 |
| 1/500 | 1.00 | £10.02 | 99.80% | -50000 |
| 1/200 | 1.00 | £10.05 | 99.50% | -20000 |
| 1/100 | 1.01 | £10.10 | 99.01% | -10000 |
| 1/66 | 1.01 | £10.15 | 98.51% | -6600 |
| 1/50 | 1.02 | £10.20 | 98.04% | -5000 |
| 1/33 | 1.03 | £10.30 | 97.06% | -3300 |
| 1/25 | 1.04 | £10.40 | 96.15% | -2500 |
| 1/20 | 1.05 | £10.50 | 95.24% | -2000 |
| 1/16 | 1.06 | £10.63 | 94.12% | -1600 |
| 1/14 | 1.07 | £10.71 | 93.33% | -1400 |
| 1/12 | 1.08 | £10.83 | 92.31% | -1200 |
| 1/10 | 1.10 | £11.00 | 90.91% | -1000 |
| 1/9 | 1.11 | £11.11 | 90.00% | -900 |
| 1/8 | 1.12 | £11.25 | 88.89% | -800 |
| 1/7 | 1.14 | £11.43 | 87.50% | -700 |
| 1/6 | 1.16 | £11.67 | 85.71% | -600 |
| 2/11 | 1.18 | £11.82 | 84.62% | -550 |
| 1/5 | 1.20 | £12.00 | 83.33% | -500 |
| 2/9 | 1.22 | £12.22 | 81.82% | -450 |
| 1/4 | 1.25 | £12.50 | 80.00% | -400 |
| 2/7 | 1.28 | £12.86 | 77.78% | -350 |
| 3/10 | 1.30 | £13.00 | 76.92% | -333.33 |
| 1/3 | 1.33 | £13.33 | 75.00% | -300 |
| 7/20 | 1.35 | £13.50 | 74.07% | -285.71 |
| 4/11 | 1.36 | £13.64 | 73.33% | -275 |
| 2/5 | 1.40 | £14.00 | 71.43% | -250 |
| 4/9 | 1.44 | £14.44 | 69.23% | -225 |
| 9/20 | 1.45 | £14.50 | 68.97% | -222.22 |
| 1/2 | 1.50 | £15.00 | 66.67% | -200 |
| 8/15 | 1.53 | £15.33 | 65.22% | -187.50 |
| 11/20 | 1.55 | £15.50 | 64.52% | -181.82 |
| 4/7 | 1.57 | £15.71 | 63.64% | -175 |
| 3/5 | 1.60 | £16.00 | 62.50% | -166.67 |
| 8/13 | 1.61 | £16.15 | 61.90% | -162.50 |
| 5/8 | 1.62 | £16.25 | 61.54% | -160 |
| 13/20 | 1.65 | £16.50 | 60.61% | -153.85 |
| 4/6 | 1.66 | £16.67 | 60.00% | -150 |
| 7/10 | 1.70 | £17.00 | 58.82% | -142.86 |
| 5/7 | 1.71 | £17.14 | 58.33% | -140 |
| 8/11 | 1.72 | £17.27 | 57.89% | -137.50 |
| 3/4 | 1.75 | £17.50 | 57.14% | -133.33 |
| 4/5 | 1.80 | £18.00 | 55.56% | -125 |
| 5/6 | 1.83 | £18.33 | 54.55% | -120 |
| 17/20 | 1.85 | £18.50 | 54.05% | -117.65 |
| 20/23 | 1.86 | £18.70 | 53.49% | -115 |
| 9/10 | 1.90 | £19.00 | 52.63% | -111.11 |
| 10/11 | 1.90 | £19.09 | 52.38% | -110 |
| 19/20 | 1.95 | £19.50 | 51.28% | -105.26 |
| 20/21 | 1.95 | £19.52 | 51.22% | -105 |
| 1/1 | 2.00 | £20.00 | 50.00% | +100 |
| 21/20 | 2.05 | £20.50 | 48.78% | +105 |
| 11/10 | 2.10 | £21.00 | 47.62% | +110 |
| 23/20 | 2.15 | £21.50 | 46.51% | +115 |
| 6/5 | 2.20 | £22.00 | 45.45% | +120 |
| 5/4 | 2.25 | £22.50 | 44.44% | +125 |
| 13/10 | 2.30 | £23.00 | 43.48% | +130 |
| 11/8 | 2.37 | £23.75 | 42.11% | +137.50 |
| 7/5 | 2.40 | £24.00 | 41.67% | +140 |
| 29/20 | 2.45 | £24.50 | 40.82% | +145 |
| 3/2 | 2.50 | £25.00 | 40.00% | +150 |
| 6/4 | 2.50 | £25.00 | 40.00% | +150 |
| 31/20 | 2.55 | £25.50 | 39.22% | +155 |
| 8/5 | 2.60 | £26.00 | 38.46% | +160 |
| 13/8 | 2.62 | £26.25 | 38.10% | +162.50 |
| 17/10 | 2.70 | £27.00 | 37.04% | +170 |
| 7/4 | 2.75 | £27.50 | 36.36% | +175 |
| 9/5 | 2.80 | £28.00 | 35.71% | +180 |
| 15/8 | 2.87 | £28.75 | 34.78% | +187.50 |
| 19/10 | 2.90 | £29.00 | 34.48% | +190 |
| 2/1 | 3.00 | £30.00 | 33.33% | +200 |
| 21/10 | 3.10 | £31.00 | 32.26% | +210 |
| 85/40 | 3.12 | £31.25 | 32.00% | +212.50 |
| 11/5 | 3.20 | £32.00 | 31.25% | +220 |
| 9/4 | 3.25 | £32.50 | 30.77% | +225 |
| 23/10 | 3.30 | £33.00 | 30.30% | +230 |
| 12/5 | 3.40 | £34.00 | 29.41% | +240 |
| 5/2 | 3.50 | £35.00 | 28.57% | +250 |
| 13/5 | 3.60 | £36.00 | 27.78% | +260 |
| 27/10 | 3.70 | £37.00 | 27.03% | +270 |
| 11/4 | 3.75 | £37.50 | 26.67% | +275 |
| 14/5 | 3.80 | £38.00 | 26.32% | +280 |
| 29/10 | 3.90 | £39.00 | 25.64% | +290 |
| 3/1 | 4.00 | £40.00 | 25.00% | +300 |
| 16/5 | 4.20 | £42.00 | 23.81% | +320 |
| 13/4 | 4.25 | £42.50 | 23.53% | +325 |
| 10/3 | 4.33 | £43.33 | 23.08% | +333.33 |
| 100/30 | 4.33 | £43.33 | 23.08% | +333.33 |
| 17/5 | 4.40 | £44.00 | 22.73% | +340 |
| 7/2 | 4.50 | £45.00 | 22.22% | +350 |
| 18/5 | 4.60 | £46.00 | 21.74% | +360 |
| 15/4 | 4.75 | £47.50 | 21.05% | +375 |
| 19/5 | 4.80 | £48.00 | 20.83% | +380 |
| 4/1 | 5.00 | £50.00 | 20.00% | +400 |
| 17/4 | 5.25 | £52.50 | 19.05% | +425 |
| 9/2 | 5.50 | £55.00 | 18.18% | +450 |
| 19/4 | 5.75 | £57.50 | 17.39% | +475 |
| 5/1 | 6.00 | £60.00 | 16.67% | +500 |
| 11/2 | 6.50 | £65.00 | 15.38% | +550 |
| 6/1 | 7.00 | £70.00 | 14.29% | +600 |
| 13/2 | 7.50 | £75.00 | 13.33% | +650 |
| 7/1 | 8.00 | £80.00 | 12.50% | +700 |
| 15/2 | 8.50 | £85.00 | 11.76% | +750 |
| 8/1 | 9.00 | £90.00 | 11.11% | +800 |
| 17/2 | 9.50 | £95.00 | 10.53% | +850 |
| 9/1 | 10.00 | £100.00 | 10.00% | +900 |
| 19/2 | 10.50 | £105.00 | 9.52% | +950 |
| 10/1 | 11.00 | £110.00 | 9.09% | +1000 |
| 11/1 | 12.00 | £120.00 | 8.33% | +1100 |
| 12/1 | 13.00 | £130.00 | 7.69% | +1200 |
| 14/1 | 15.00 | £150.00 | 6.67% | +1400 |
| 16/1 | 17.00 | £170.00 | 5.88% | +1600 |
| 18/1 | 19.00 | £190.00 | 5.26% | +1800 |
| 20/1 | 21.00 | £210.00 | 4.76% | +2000 |
| 22/1 | 23.00 | £230.00 | 4.35% | +2200 |
| 25/1 | 26.00 | £260.00 | 3.85% | +2500 |
| 28/1 | 29.00 | £290.00 | 3.45% | +2800 |
| 30/1 | 31.00 | £310.00 | 3.23% | +3000 |
| 33/1 | 34.00 | £340.00 | 2.94% | +3300 |
| 35/1 | 36.00 | £360.00 | 2.78% | +3500 |
| 38/1 | 39.00 | £390.00 | 2.56% | +3800 |
| 40/1 | 41.00 | £410.00 | 2.44% | +4000 |
| 45/1 | 46.00 | £460.00 | 2.17% | +4500 |
| 50/1 | 51.00 | £510.00 | 1.96% | +5000 |
| 55/1 | 56.00 | £560.00 | 1.79% | +5500 |
| 60/1 | 61.00 | £610.00 | 1.64% | +6000 |
| 66/1 | 67.00 | £670.00 | 1.49% | +6600 |
| 70/1 | 71.00 | £710.00 | 1.41% | +7000 |
| 80/1 | 81.00 | £810.00 | 1.23% | +8000 |
| 90/1 | 91.00 | £910.00 | 1.10% | +9000 |
| 100/1 | 101.00 | £1010.00 | 0.99% | +10000 |
| 150/1 | 151.00 | £1510.00 | 0.66% | +15000 |
| 200/1 | 201.00 | £2010.00 | 0.50% | +20000 |
| 250/1 | 251.00 | £2510.00 | 0.40% | +25000 |
| 500/1 | 501.00 | £5010.00 | 0.20% | +50000 |
| 750/1 | 751.00 | £7510.00 | 0.13% | +75000 |
| 1000/1 | 1001.00 | £10010.00 | 0.10% | +100000 |
| 5000/1 | 5001.00 | £50010.00 | 0.02% | +500000 |
| 10000/1 | 10001.00 | £100010.00 | 0.01% | +1000000 |
Two notes on the numbers. The decimal column is cut off at two places rather than rounded, because that's how a bookmaker prints it: 4/6 displays as 1.66, not 1.67. The returns column is worked out from the fraction itself, so 4/6 actually pays £16.67 on a tenner. That penny gap isn't a rounding error at our end, it's the difference between the price displayed and the price settled, and it's why we never round a back price up.
The overround is why picking winners doesn't work for almost anybody. You aren't only beating the result, you're beating the result plus five per cent, every bet, forever. Get the outcome right slightly more often than the market and you still finish behind.
The promotions are the exception, because a free bet has no margin in it. It's marketing spend rather than a priced-up market, so it's the one corner of a bookmaker's book where the numbers point at you. Matched betting is the technique for collecting them.
The mechanic is short. Back a selection at the bookmaker, lay the same selection at an exchange, and every result is covered. On an ordinary qualifying bet that costs you pennies, and it unlocks the promotion. Repeat it with the free bet and most of the face value converts to cash: a £10 free bet usually comes out somewhere around £7.50 to £8, with nothing riding on the score.
Nobody is being robbed here. Bookmakers know precisely what this costs them and pay it anyway, because most people who claim an offer stay for the normal-priced bets afterwards. That's the part the 105% is waiting for.
If you want to try it, our no-risk matched betting guide covers the concept and a first offer end to end. The oddsmatcher finds the selections where back and lay sit closest together, the matched betting calculator does the lay stake sums, and every live offer we've priced sits on the betting offers page.
Because that's how a bookmaker prints it. The exact value is 1.6667 and the display is cut off rather than rounded, which also keeps a back price from ever looking better than it is. Settlement still uses the fraction, so a tenner at 4/6 pays £16.67, which is the figure in the returns column of the table.
Odds are an opinion with a margin added, and both halves vary between firms. The same runner can be 2.50 in one place and 2.75 in another, which is why it pays to look at more than one before placing anything. An exchange price is the useful reference because it carries no margin.
No, it's always the more optimistic of the two, because the bookmaker's margin is baked in. In a 105% book every price overstates the true chance by roughly its share of that surplus. Strip the margin out and you land closer to an honest number, which is what the exchange price is doing.
An exchange charges commission on winnings instead of building a margin into the price, so its book sits near 100% rather than 105%. That's why exchange odds are usually a bit bigger, and why a bookmaker price sitting close to the exchange lay price is a good one.
Decimal, and it isn't close. Every lay stake, qualifying loss and free bet calculation is written in decimal, exchanges quote nothing else, and one bad conversion halfway through a bet is how people end up unbalanced with money on one side.
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