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Betting Calculators

Convert odds, see the probability a price implies, measure a bookmaker's margin, check the value you got against the closing line, split an arbitrage stake and price an accumulator. Type in any format: 2.10, 11/10, evens or +110.

Odds converter

Decimal
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Fractional
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American
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Implied probability
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Decimal odds are the return per unit staked, stake included: fractional 11/10 is 11 ÷ 10 + 1 = 2.10. American odds quote the profit on 100 (+110) or the stake needed to win 100 (-110). Implied probability is 100 ÷ decimal odds, so 2.10 implies 47.6%. A fraction shown here is the nearest price UK bookmakers quote.

Margin and fair odds

Enter a bookmaker's prices on every outcome of one market. Leave the draw empty for a two-way market.

OutcomePriceImpliedFair chanceFair odds
Implied total
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Margin
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Payout
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The implied probabilities of a market add up to more than 100%; the excess is the margin (overround) and 100 ÷ total is the payout. Fair chance divides each implied probability by the total, and fair odds are 100 ÷ fair chance. Example: 2.10, 3.40 and 3.60 imply 47.6% + 29.4% + 27.8% = 104.8%, a 4.8% margin and a 95.4% payout; the fair home price is 2.20. Every odds grid on this site shows the payout per bookmaker worked out this way.

Closing line value

The price you took, and the price your selection closed at just before the start. Add the closing prices of the other outcomes to measure against the fair closing price, with the margin removed.

CLV against the closing price
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Closing margin
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Fair closing price
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CLV against fair close
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CLV = price taken ÷ closing price - 1. Taking 2.20 on a selection that closed at 2.00 is +10%. Against the fair closing price (the closing market with its margin removed, here 2.08 when the other outcomes closed at 3.60 and 3.80) it is +5.7%: that is the figure to track, because a bet only beats the market when its value clears the margin. One bet proves nothing; a record of positive CLV over many bets is the strongest sign of a good price. The closing prices of every match on this site are kept after the game, bookmaker by bookmaker, on its match page.

Arbitrage stakes

The best price on each outcome, usually from different bookmakers, and the total you want to stake. Leave the third price empty for a two-way market.

OutcomePriceStakeReturns
Implied total
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Profit
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When the implied probabilities of the best prices add up to less than 100%, staking each outcome in proportion to its implied probability returns the same amount whichever wins: stake × implied ÷ total. At 2.10 and 2.05 the total is 96.4%, so £100 goes £51.80 and £48.20 for a return of about £103.70 and a profit of 3.7%. Above 100% there is no arbitrage, only the margin. Bookmakers restrict accounts that bet this way, prices move while you place the legs, and a voided leg leaves the other one open. The sure bets page lists the arbitrages open at the bookmakers you can use.

Accumulator

The price of each leg and your stake. Add up to ten legs.

Legs
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Combined odds
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Implied chance
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Returns
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Profit
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Accumulator odds are the decimal prices multiplied together: 1.50 × 1.80 × 2.00 × 1.60 = 8.64, so £10 returns £86.40. Every leg has to win, and the implied chance of that is 100 ÷ 8.64 = 11.6%. Each leg carries the bookmaker's margin, so the margin compounds: four legs at 5% each keep about 19% of the fair return. The betting guides cover accumulators, each-way bets and the main markets.

Betting calculator FAQ

How do I convert fractional odds to decimal odds?
Divide the first number by the second and add one. 11/10 is 11 ÷ 10 + 1 = 2.10. Evens is 1/1, so 2.00. Decimal odds include your stake: a £10 bet at 2.10 returns £21, of which £11 is profit.
What is the implied probability of a price?
Divide 100 by the decimal odds. A price of 2.50 implies a 40% chance; 1.50 implies 66.7%. Across all the outcomes of a market the implied probabilities add up to more than 100%: the extra is the bookmaker's margin.
What is the bookmaker's margin, or overround?
The amount by which the implied probabilities of every outcome add up to more than 100%. A 1X2 market at 2.10, 3.40 and 3.60 implies 47.6% + 29.4% + 27.8% = 104.8%, a margin of 4.8%. The payout is the reverse: 100 ÷ 104.8 = 95.4% of stakes returned over the long run. Fair odds are the prices with that margin removed.
What is closing line value (CLV)?
The difference between the price you took and the price the market closed at just before kick-off, as a percentage. Taking 2.20 on a selection that closed at 2.00 is +10% CLV. Measured against the fair closing price (the margin removed), closing line value is the most reliable sign that a bet was priced well, because the closing line is the sharpest price the market produces. A positive CLV does not make any single bet a winner.
How are arbitrage (sure bet) stakes worked out?
Take the best price on each outcome from different bookmakers. If their implied probabilities add up to less than 100%, splitting the stake in proportion to those probabilities returns the same amount whichever outcome wins. At 2.10 and 2.05 on a two-way market the implied total is 96.4%, so £100 split £51.80 and £48.20 returns about £103.70 either way. Bookmakers can limit or close accounts that bet this way, and a voided leg leaves the other open.
How are accumulator odds worked out?
Multiply the decimal odds of every leg. Four selections at 1.50, 1.80, 2.00 and 1.60 give 1.5 × 1.8 × 2.0 × 1.6 = 8.64, so £10 returns £86.40. Every leg must win, and the implied chance of that is 100 ÷ 8.64 = 11.6%. The bookmaker's margin is taken on every leg, so it compounds: four legs at a 5% margin each cost about 19% of the fair return.

These calculators show what the arithmetic of a price is. They do not predict results. 18+, please gamble responsibly: BeGambleAware.org.