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On this page
- Odds Converter and Implied Probability Calculator
- How do fractional odds work?
- How do decimal odds work?
- What are American (moneyline) odds?
- Odds conversion table
- What do odds-on and odds-against mean?
- What are each-way place odds?
- What does SP mean in betting?
- Odds and free bets
- Current sports offers
- Frequently asked questions
- Staying in control
- Sources checked
Last checked 21 October 2026 by Tom Perkins. Calculations checked by us against the rules cited below.
Fractional odds show winnings relative to stake (5/1 means £5 profit per £1). Decimal odds show the total return per £1 including stake (5/1 is 6.0). American odds show profit on £100 (+500) or the stake needed to win £100 (−200). They all describe the same price.
How do fractional odds work?
Traditional in UK and Irish racing. The first number is the winnings for a stake of the second number. At 5/2 a £2 stake wins £5, and you also get your stake back. Odds-on prices such as 1/2 pay less than the stake: £10 at 1/2 wins £5. “Evens” (1/1) doubles your money.
Return = stake × (numerator ÷ denominator) + stake. £10 at 5/2 returns £10 × 2.5 + £10 = £35.
How do decimal odds work?
Used by exchanges and offered by most UK bookmakers as a display setting. Return = stake × decimal odds. £10 at 3.5 returns £35, the same as 5/2. To convert fractional to decimal, divide and add 1: 5/2 → 2.5 + 1 = 3.5.
What are American (moneyline) odds?
Positive numbers show profit on a 100 stake: +250 = 5/2. Negative numbers show how much to stake to win 100: −200 = 1/2. You will see them on US sports and boxing/UFC coverage.
Odds conversion table
| Fractional | Decimal | American | Implied probability |
|---|---|---|---|
| 1/5 | 1.20 | -500 | 83.3% |
| 1/4 | 1.25 | -400 | 80.0% |
| 1/3 | 1.33 | -300 | 75.0% |
| 1/2 | 1.50 | -200 | 66.7% |
| 4/6 | 1.67 | -150 | 60.0% |
| 4/5 | 1.80 | -125 | 55.6% |
| 10/11 | 1.91 | -110 | 52.4% |
| Evens (1/1) | 2.00 | +100 | 50.0% |
| 11/10 | 2.10 | +110 | 47.6% |
| 6/5 | 2.20 | +120 | 45.5% |
| 5/4 | 2.25 | +125 | 44.4% |
| 6/4 | 2.50 | +150 | 40.0% |
| 7/4 | 2.75 | +175 | 36.4% |
| 2/1 | 3.00 | +200 | 33.3% |
| 9/4 | 3.25 | +225 | 30.8% |
| 5/2 | 3.50 | +250 | 28.6% |
| 3/1 | 4.00 | +300 | 25.0% |
| 7/2 | 4.50 | +350 | 22.2% |
| 4/1 | 5.00 | +400 | 20.0% |
| 5/1 | 6.00 | +500 | 16.7% |
| 6/1 | 7.00 | +600 | 14.3% |
| 8/1 | 9.00 | +800 | 11.1% |
| 10/1 | 11.00 | +1000 | 9.1% |
| 14/1 | 15.00 | +1400 | 6.7% |
| 20/1 | 21.00 | +2000 | 4.8% |
| 33/1 | 34.00 | +3300 | 2.9% |
| 50/1 | 51.00 | +5000 | 2.0% |
| 100/1 | 101.00 | +10000 | 1.0% |
Implied probabilities are rounded. Implied probability explained shows how they are worked out and why they add up to more than 100% across a market.
What do odds-on and odds-against mean?
- Odds-against (longer than evens, e.g. 3/1): winnings exceed the stake.
- Odds-on (shorter than evens, e.g. 4/6): winnings are less than the stake.
- Favourite: the shortest price in the market. A joint favourite shares that price.
What are each-way place odds?
Place odds are a fraction of the win odds, which is how each-way bets pay out when your selection only places. At 10/1 with 1/5 odds a place, the place part is paid at 2/1 (3.0 in decimal). The fraction and the number of places are set by the race or market terms, so check them on the bet slip.
What does SP mean in betting?
If you take SP rather than a fixed price, the bet is settled at the official starting price returned when the race starts. Best Odds Guaranteed is a promotion some bookmakers offer on racing, which pays the better of your price and SP; its terms vary by operator.
Odds and free bets
Most free bets don’t return the stake, so a £10 free bet at 3.0 returns £20, not £30. Offers also set minimum odds, often in fractional and decimal. See free bets and how to claim free bets.
Current sports offers
The offers below are for new customers aged 18+ at UKGC-licensed bookmakers. Each one has its own terms, minimum odds and expiry, so read them before you opt in. Our free bets page explains how tokens work.
New customers. Min £5 deposit. First bet only: min £5 single/each-way at odds 1/1+ within 30 days of registration. 3 x £10 Free Bets (singles/each-way, excl. virtuals), expire after 30 days. Free Bet stakes not returned. Neteller and Skrill deposits excluded. No wagering on Free Bet winnings stated.
Promo code:
AB5G30Three separate £10 Free Bets, usable on singles and each-way.Full T&Cs
New Sky Betting and Gaming customers 18+ only (previous Sky Bet, Vegas, Casino, Bingo or Poker account holders excluded). Register, add card details and make a minimum £5 deposit. Your first bet must be a single or each-way bet of at least £5 on any Sky Bet market at odds of 1/1 or greater; accumulated smaller stakes do not count and only your first bet counts. Staking requirement must be met within 30 days of registration. Rewards: three £10 Free Bet tokens, usable on any single or each-way market excluding virtuals, not with any other offer. Free Bets expire 30 days after crediting, are non-withdrawable and stakes are not included in returns. One claim per customer. Customers depositing with Neteller or Skrill do not qualify. Offer may differ if you arrive via another link. Sky Bet General Promotion Terms apply.
New customers. Opt in at sign-up. Deposit £10+ and place a £10+ bet at odds 1/1+ within 7 days (excl. virtuals, esports, non-UK/IE racing). 4 x £10 Free Bets: 2 for football accas (4+ legs), 2 for sports multiples (2+ legs), valid 7 days. Free Bet stake not returned.
Rewards credited on settlement of one £10 qualifying bet, win or lose.
Full T&Cs
New BetMGM customers 18+. Select the Sports Welcome Offer at sign-up. Deposit at least £10 and place at least £10 on a qualifying bet within 7 days of registration: min odds Evens 1/1 (2.0); each-way bets need £10 each way (£20 total); Bet Builder total odds must be 1/1+. Excludes virtual sports, esports and non-UK/IE horse racing. Free Bets, Profit Boosts, Odds Boosts, void, cashed-out, partially cashed-out and system bets do not qualify. Not with other offers. On settlement you get 4 x £10 Free Bets: 2 x £10 on football accas (4+ selections) and 2 x £10 on sports multiples (2+ selections), selected via the betslip checkbox. Free Bets expire after 7 days; stake not included in winnings. Once per household/computer/IP. Operated by LeoVegas Gaming plc (UKGC 39198). General and promotional T&Cs apply.
New customers. Opt in at sign-up. Deposit £10+ and place a £10+ bet at odds 1/1+ within 7 days (excl. virtuals, esports, non-UK/IE racing). 4 x £10 Free Bets: 2 for football accas (4+ legs), 2 for sports multiples (2+ legs), valid 7 days. Free Bet stake not returned.
Same LeoVegas offer structure as BetMGM, with UK/IE racing allowed for the qualifier.
Full T&Cs
New BetUK.com customers 18+. Opt in by selecting the Sports Welcome Offer at sign-up. Deposit at least £10 and place at least £10 on a qualifying bet within 7 days of registration: min odds Evens 1/1 (2.0); each-way needs £10 each way; Bet Builder total odds 1/1+. Excludes virtual sports, esports and non-UK/IE horse racing. Free Bets, Profit/Odds Boosts, void, cashed-out, partially cashed-out and system bets do not qualify. Once only; not with other offers. On settlement: 2 x £10 Free Bets on football accas (4+ selections) and 2 x £10 on sports multiples (2+ selections). Unused Free Bets expire after 7 days; stake not included in winnings. Operated by LeoVegas Gaming plc (UKGC 39198). General Promotional and General T&Cs apply.
Frequently asked questions
What does 11/10 mean? You win £11 for every £10 staked, plus your stake back. In decimal it is 2.10.
Is 4/6 or 4/5 shorter? 4/6 (1.67) is shorter, meaning the bookmaker rates it more likely, than 4/5 (1.80).
What does 100/30 mean? It equals 10/3, or 4.33 in decimal.
Why do UK bookmakers still use fractions? Fractions are the tradition in UK racing. Most bookmakers let you switch to decimal in settings.
Do odds tell me the chance of winning? They imply a probability, but that includes the bookmaker’s margin. See our implied probability guide.
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Staying in control
Set a deposit limit before your first deposit, decide your budget in advance and never chase losses. Calculators show what a bet could return; they do not make any outcome more likely. You can self-exclude from all online gambling sites licensed in Great Britain for free with GamStop, and many banks let you block gambling payments. The National Gambling Helpline (0808 8020 133) is free, confidential and open 24 hours a day. See our responsible gambling page.
Sources checked
- Conversion maths verified with our unit-tested converter
Affiliate disclosure: onlinebetfree.co.uk may receive a commission if you open an account through links on this page. This does not affect the offers we list or how we describe them, and it never changes the terms an operator gives you.
18+ only. Please gamble responsibly. For free, confidential support visit BeGambleAware.org or call the National Gambling Helpline on 0808 8020 133.