Betting Odds Calculator – Convert Odds and Work Out Payouts
One price, three ways of writing it. Type odds in whichever format your bookmaker shows — American like -150, decimal like 1.667, or fractional like 2/3 — and see the other two formats, the implied probability hiding inside the price, and exactly what a winning stake pays back: profit and total payout, to the cent.
Your odds
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What the price means
The same price, three ways
A favourite’s price
Negative odds mark the favourite — the profit is smaller than the stake, because the outcome is priced as more likely than not. At -150, a $100 stake wins $66.67 of profit.
- Every odds format is a probability wearing a different coat — convert the price to its implied probability and any two prices compare on one honest scale.
- The stake coming back to you is never profit — profit and total payout are shown as two separate numbers, to the cent.
- A price is not a prediction — the implied probability is the chance the price assumes, to hold against your own judgement of the outcome.
See the chance
The marker sits at the implied probability — the share of the time this outcome would need to happen for the price to be exactly fair. Past the halfway line, the price calls it more likely than not.
At 60.00%, odds of -150 sit on the favourite’s side of the line — the price says this is more likely to happen than not.
The one idea underneath all of it
Every odds format is a probability wearing a different coat, with a price tag attached. Convert the price to its implied probability and you can compare any two bookmakers, any two sports, any two formats on one honest scale — and you can see the margin the bookmaker built in, because the implied probabilities of every outcome in a market add up to more than 100 percent.
Pairs well with this calculation
Odds are probability and percentages in disguise — these three do the underlying sums.
Probability Calculator
The chance of one event, or several combined — the maths the implied percentage comes from.
Percentage Calculator
Clean percentage arithmetic — the same sums that sit underneath implied probability.
Fraction Calculator
Add, simplify and convert fractions — the arithmetic behind fractional odds.
Odds, converted in three steps
Start from your format
Type the odds exactly as your bookmaker shows them, into the matching box. The other two boxes convert instantly, so a price never has to be transcribed or converted by hand — the likeliest place for a costly slip.
Read the implied probability
The big number is the chance the price assumes. Hold it against your own judgement of the outcome. That gap — your estimate versus the price’s — is the entire story of whether a price is generous or short.
Add your stake
Enter what you would put down and read the profit and the total payout as two separate numbers, to the cent. The stake coming back to you is never profit, and this is where that stays impossible to confuse.
How the betting odds calculator works
American → decimal: positive, 1 + odds ÷ 100 · negative, 1 + 100 ÷ |odds| · implied % = 100 ÷ decimal
A favourite. Odds of -150. Decimal: 1 + 100/150 = 1.667. Implied probability: 100 / 1.667 = 60.00%. Fractional: 1.667 − 1 = 0.667, written as the fraction 2/3. A $100 stake profits 100 × 2/3 = $66.67 and pays out $166.67 in total.
An underdog. Odds of +200. Decimal: 1 + 200/100 = 3.00. Implied probability: 100 / 3.00 = 33.33%. Fractional: 3.00 − 1 = 2, written as 2/1. A $50 stake profits 50 × 2 = $100.00 and pays out $150.00 in total.
Starting from a fraction. Odds of 5/2. Decimal: 1 + 5/2 = 3.50. American: (3.50 − 1) × 100 = +250. Implied probability: 100 / 3.50 = 28.57%. The fraction is the profit ratio itself — five units of profit for every two units staked.
Profit and payout. Two multiplications finish every conversion. Profit is the stake times everything above 1 in the decimal odds: stake × (decimal − 1). Payout is the stake times the whole decimal figure: stake × decimal. The difference between the two results is always exactly your stake, which is the built-in check on the arithmetic.
How the fraction is found. Turning decimal odds back into a fraction means subtracting 1 and writing what remains as the simplest fraction: 1.909 − 1 = 0.909, which is 10/11 — the familiar -110 price. This page finds it by continued fractions, allowing denominators up to 100, so the fraction shown is the nearest clean one to the exact figure, and common bookmaker prices come out exact.
Going deeper
Each format grew up somewhere different, and each tells the same truth in a different accent. Fractional odds are the oldest, from British and Irish racing: they quote the profit ratio directly, so 5/2 reads aloud as “five to two” — five units of profit against two staked. They suit racing because prices there were struck between people, in words, long before screens.
American odds, the moneyline, are built around a standard $100. A negative number says what you must stake to win $100; a positive number says what a $100 stake wins. Decimal odds, standard in Europe, Australia and Canada and near-universal online, quote the total return instead: stake included, one clean multiplier. Nothing about the underlying bet changes between the three — only what the number puts in front of you first: profit, stake, or total return.
Convert every outcome in a market to its implied probability and add them up. If the prices were perfectly fair, the total would be exactly 100%. In a real market it never is. A two-sided contest priced at -110 both ways implies 52.38% + 52.38% = 104.76%. The extra 4.76% — the overround — is the bookmaker’s cushion, spread across every runner.
That cushion is why conversion matters. A price can only be generous relative to the true chance, and the implied probability is the price translated into the same units as your judgement. Spot a price implying 40% for something you rate a genuine 50% chance and the arithmetic is in your favour on paper; mistake a short price for a good one and the margin quietly collects. The calculator cannot tell you the true chance — nobody can — but it makes sure the price’s side of the comparison is never the part you get wrong.
One price, three readings: favourite and underdog side by side
The same price means the same thing in every format — only what the number puts in front of you first changes. Both rows below were run through this page’s own calculator.
| American odds | Decimal odds | Fractional odds | Implied probability | Profit on $100 | Total payout on $100 |
|---|---|---|---|---|---|
| −150 (favourite) | 1.667 | 2/3 | 60.00% | $66.67 | $166.67 |
| +200 (underdog) | 3.00 | 2/1 | 33.33% | $200.00 | $300.00 |
The favourite row is the page’s default: odds of −150 mean the outcome is priced as more likely than not, and the number is the stake that would win $100 of profit — put down $150 to win $100, so a $100 stake wins $66.67 and pays out $166.67 in total. The conversion runs: decimal = 1 + 100/150 = 1.667; implied probability = 100 / 1.667 = 60.00%; fractional = 1.667 − 1 = 0.667, written as 2/3. The underdog row is the mirror: odds of +200 mean a $100 stake wins $200, so decimal = 1 + 200/100 = 3.00, implied probability = 100 / 3.00 = 33.33%, and fractional = 3.00 − 1 = 2, written as 2/1. A $50 stake on the underdog would profit $100.00 and pay out $150.00 — the same price, half the stake, half the money, exactly as linearity requires.
The stake experiment on the favourite row makes the profit-versus-payout distinction unmissable. At −150, a $100 stake profits $66.67 and pays out $166.67; halve the stake to $50 and the profit halves to $33.33 while the payout becomes $83.33. The difference between profit and payout is always exactly the stake — $166.67 − $66.67 = $100.00, and $83.33 − $33.33 = $50.00 — which is the built-in check on the arithmetic: if your profit and payout ever differ by anything other than your stake, something was mistyped. The stake coming back to you is never profit, and this page keeps the two numbers in separate rows precisely so that stays impossible to confuse. Any “winnings” figure that includes the stake is a payout, not a profit, and comparing payouts across bets without subtracting stakes is comparing different things.
The margin hiding inside every price
Convert every outcome in a market to its implied probability and add them up. If the prices were fair — if they reflected true chances with no margin — the total would be exactly 100%. It never is. Price both sides of an even contest at −110 and each side implies 52.38% (100 / 1.909, since −110 converts to decimal 1.909), giving a total of 104.76%. The extra 4.76% is the overround: the cushion built into the prices, and the reason the odds on offer are always a little worse than the fair odds on every side of a market. The page’s own FAQ states this figure, and it is the most important number for anyone reading prices seriously — because it means the market, taken as a whole, implies more than certainty. No selection in that market can be “good value” against the fair odds without first overcoming the margin, and the margin is the bookmaker’s edge, collected quietly on every bet regardless of who wins.
The practical reading of implied probability follows from the margin, not from any promise. The big number on this page is the chance the price assumes: hold it against your own judgement of the outcome, and the gap between your estimate and the price’s is the entire story of whether a price is generous or short. If you judge an outcome at 50% and the price implies 33.33% (as +200 does), the price is generous relative to your judgement — and if you judge it at 25%, the same price is short. Neither reading is a prediction and neither is a system: the price is a market’s opinion with a margin inside it, your judgement is an opinion without one, and the gap between opinions is information, not income. No combination of conversions, stakes or formats changes the margin or manufactures an edge; the calculator converts prices, it does not improve them. Bet only what you can afford to lose, and treat any price — however generous it looks against your judgement — as a price for an uncertain outcome, not as money waiting to be collected.
Starting from a fraction, and finding fractions from decimals
Fractional odds are the profit ratio itself, which makes them the most direct format to reason from. Odds of 5/2 read aloud as “five to two”: five units of profit for every two units staked. The conversion is: decimal = 1 + 5/2 = 3.50; American = (3.50 − 1) × 100 = +250; implied probability = 100 / 3.50 = 28.57%. The fraction tells you the profit before any conversion — a $20 stake at 5/2 profits $50.00 (20 × 5/2) and pays out $70.00 — which is why fractional odds suit racing, where prices were struck between people, in words, long before screens. The reverse direction, turning decimal odds back into a fraction, means subtracting 1 and writing what remains as the simplest fraction: 1.909 − 1 = 0.909, which is 10/11 — the familiar −110 price. This page finds the fraction by continued fractions, allowing denominators up to 100, so the fraction shown is the nearest clean one to the exact figure, and common bookmaker prices come out exact. When the fraction looks unfamiliar, it is usually the nearest clean fraction to an awkward decimal, not an error — check the decimal and the implied probability, which are exact, before doubting the fraction.
Three formats, three homes — and one truth
Each format grew up somewhere different, and each tells the same truth in a different accent. Fractional odds are the oldest, from British and Irish racing: they quote the profit ratio directly. American odds, the moneyline, are built around a standard $100: a negative number says what you must stake to win $100, a positive number says what a $100 stake wins. Decimal odds, standard in Europe, Australia and Canada and near-universal online, quote the total return instead: stake included, one clean multiplier. Nothing about the underlying bet changes between the three — only what the number puts in front of you first: profit, stake, or total return. The most common conversion error is not arithmetic but format confusion: treating a decimal figure as a profit ratio (forgetting the stake inside it), or treating an American negative as a loss rather than a stake-to-win-$100. Type the odds exactly as your bookmaker shows them, into the matching box, and let the other two boxes convert — the likeliest place for a costly slip is transcribing or converting by hand, and this page exists so you never have to.
Evens, heavy favourites, and why no price is a lock
Two more prices complete the education this page gives: the even-money price where profit equals stake, and the heavy favourite where the price implies near-certainty — and shows why near-certainty is still not certainty.
| American odds | Decimal odds | Fractional odds | Implied probability | Profit on $100 | Total payout on $100 |
|---|---|---|---|---|---|
| +100 (evens) | 2.00 | 1/1 | 50.00% | $100.00 | $200.00 |
| −900 (heavy favourite) | 1.111 | 1/9 | 90.00% | $11.11 | $111.11 |
Evens is the hinge the whole American system swings on. At +100, a $100 stake wins $100 of profit and pays out $200 in total — profit equals stake, decimal odds are exactly 2.00, fractional odds are 1/1, and the implied probability is exactly 50.00%. Every negative price is a favourite priced above evens (more likely than not, profit smaller than stake) and every positive price above +100 is an underdog priced below evens (less likely than not, profit larger than stake). The American system’s $100 standard makes that hinge visible: negative numbers answer “what must I stake to win $100?”, positive numbers answer “what does $100 win?”, and +100 is the one price where both questions have the same answer. If you ever lose track of which side of evens a price sits on, convert it: decimal above 2.00 means underdog, below 2.00 means favourite, exactly 2.00 means evens — the decimal figure never lies about the side, because it is the total return multiplier and 2.00 is the doubling point.
The heavy favourite row is the responsible-framing row, and it deserves slow reading. At −900 the price implies a 90.00% chance: decimal 1.111, fractional 1/9, profit $11.11 on a $100 stake, payout $111.11. Ninety percent sounds like a lock, and it is not — it is nine wins in ten, which means one loss in ten, and the loss on a $100 stake at −900 is not $11.11 but $100.00, because a losing favourite’s stake does not come back. The asymmetry is the whole risk story of heavy favourites: nine wins of $11.11 total $99.99, and one loss of $100.00 wipes them out — before the margin is even counted. That arithmetic is not an argument for or against betting on favourites; it is the reason “90% chance” must never be read as “certain”, and why staking a large amount to win a small profit needs the same sober judgement as any other bet. The calculator converts the price exactly; it cannot tell you whether the 90% is right, and no price, however short, converts uncertainty into income.
Reading a full market, not just one price, is where the overround stops being an abstraction. Take an illustrative three-outcome market whose prices imply 45%, 35% and 25% — three figures that add to 105%, so the overround is 5%. No outcome’s implied probability can be taken at face value until that 5% is acknowledged: if the margin were removed proportionally, the fair chances would be roughly 42.86%, 33.33% and 23.81% (each implied figure divided by 1.05), and every selection’s price is shorter than its fair chance by that same proportion. The proportional removal is an illustration of the method, not a claim about any real market — real margins are not spread evenly, and bookmakers shade popular outcomes more heavily than obscure ones — but it shows the direction and the size of the adjustment. A market with a 5% overround pays out, on average, 95 cents of fair value per dollar staked across all outcomes, before anyone’s judgement enters the picture. That is the headwind every selection faces, and it is why “finding value” means finding a gap between price and judgement larger than the margin, not merely finding a price you like.
Stake discipline belongs in the same section, because the size of the stake is the one risk control the calculator cannot set for you. A flat stake — the same amount on every bet, whatever the price — makes losses predictable: ten losing $100 stakes cost $1,000, no matter what the prices were. A stake that grows after losses to “win it back” does the opposite: it concentrates risk exactly when judgement is most likely to be clouded, and a short run of losses at growing stakes can cost more than a long run at flat ones. No staking plan changes the margin, the implied probabilities or the outcomes; the only thing a plan changes is the shape of your own wins and losses over time. The responsible shape is the boring one: decide the stake before you look at the price, keep it small relative to what you can afford to lose, and never let a single outcome — however short its price, however certain it feels — carry money you cannot afford to lose. The calculator will convert the price exactly, whatever you stake; the staking decision is yours, and it deserves more care than the conversion.
A final discipline for reading any price: separate the price from the outcome it prices. The implied probability is the market’s opinion with a margin inside it, expressed as a percentage; your judgement is your opinion, expressed however you like; and the outcome is a fact that has not happened yet. Conversions move cleanly between the three formats because they are three writings of one price. Nothing moves cleanly between a price and a fact — that gap is what betting is, and it is why the only honest use of this calculator is to read prices clearly, compare them fairly, and stake only what you can afford to lose on an outcome that might not go your way.
Pari-mutuel betting: the pool sets the price
Horse racing, and some other markets, use a different pricing system from the fixed-odds sportsbook: pari-mutuel betting, in which the bettors bet into a pool, the operator takes a percentage, the takeout, and the remainder is divided among the winning bettors in proportion to their stakes. No bookmaker takes the other side, and no bookmaker sets the odds. The odds are determined by the pool, and they fluctuate as the money arrives, until the betting closes. The bettor does not know the final odds when the bet is placed; the odds at the moment of placing are the pool’s state at that moment, and the final odds are the pool’s verdict when it closes.
A hypothetical example, labelled as such, shows the arithmetic. Suppose a win pool holds $100,000, the takeout is 18 percent, and $20,000 is staked on the winning horse. The distributable pool is $82,000, and the payout per $1 staked on the winner is $4.10, decimal odds of 4.10, profit $3.10 per $1. If $40,000 had been staked on the winner, the payout would be $2.05, profit $1.05. The same horse, the same race, and the payout halves because the pool’s money doubled on it. The figures are invented, and the takeout rate varies by jurisdiction and by bet type, but the mechanism is the mechanism of every pari-mutuel pool: the price is the pool, the pool is the crowd, and the house’s profit is the takeout, earned whatever the outcome. The companion guide on how betting odds are calculated explains the pari-mutuel system alongside fixed odds, and the distinction between betting against the crowd and betting against the house.
Live odds: the line that never stops moving
Live odds, or in-play odds, are the line in motion, updated continuously as the event unfolds, by the bookmaker’s trading system, informed by the score, the time remaining, the momentum, and the money arriving. The live line moves faster than the pre-match line, because the information arrives faster: a goal, a touchdown, a sending-off, or an injury moves the price in seconds, and the bookmaker’s system must move the price before a bettor can exploit the stale one. The system’s speed is the bookmaker’s defence, and the bettor’s opportunity is the system’s lag: a price that has not yet moved to reflect an event the bettor has seen, on a faster feed, is a price with value, and the professional live bettor’s edge is often a faster picture, not a better model.
The live market’s margin is wider than the pre-match margin, because the bookmaker’s uncertainty is greater and the system’s speed costs money, and the wider margin raises the break-even rate on every live bet. The live market also suspends: at moments of high uncertainty, a penalty, a video review, or a goal under review, the bookmaker suspends the market and reopens it when the outcome is known, and a bet placed during a suspension is void. The suspension is the defence against the bettor who knows the outcome before the price moves, and it is a necessary part of the live market’s operation. The calculator on this page converts the live price as it converts any price, and the conversion is the same in play as before the match: the implied probability, the payout, and the break-even rate, computed from the odds as they stand. The speed is the market’s. The arithmetic is the calculator’s. The judgement is the bettor’s, and it must be made at the market’s speed. If gambling stops being fun, help is available at 1-800-GAMBLER, free and confidential.
Frequently asked questions
What do odds of -150 mean?
They mean the outcome is priced as a favourite. The number is the stake that would win $100 of profit: at -150 you put down $150 to win $100, and a winning bet pays out $250 in total. The same price is 1.667 in decimal odds and 2/3 in fractional odds, and it carries an implied probability of 60.00% — the bookmaker’s price says the outcome is more likely to happen than not.
How do I convert American odds to decimal odds?
For positive odds, divide by 100 and add 1: +200 becomes 1 + 200/100 = 3.00. For negative odds, divide 100 by the size of the number and add 1: -150 becomes 1 + 100/150 = 1.667. The decimal figure is the total return for each unit staked, with the stake itself included, which is why multiplying it by your stake gives the total payout directly.
What is implied probability?
Implied probability is the chance an outcome would need for the odds to be exactly fair, worked out as 100 divided by the decimal odds. Odds of 1.667 imply 100 / 1.667 = 60.00%. If you believe the true chance is higher than the implied probability, the price is generous on paper; if you believe it is lower, the price is short. It is a property of the price, not a prediction of what will happen.
How much does a $100 bet at +200 pay?
It pays $300 in total: $200 of profit plus your $100 stake back. In decimal terms +200 is 3.00, so the payout is the stake multiplied by the decimal odds — 100 × 3.00 = $300. Only the $200 is winnings; the rest is your own money returning to you.
What is the difference between profit and payout?
Profit is the winnings alone, on top of your stake. Payout is everything that comes back, stake included. At -150 with a $100 stake the profit is $66.67 while the payout is $166.67. Confusing the two is the most common odds mistake: a payout of $166.67 sounds bigger than it is until you remember that $100 of it was yours to begin with.
Why do the implied probabilities in a market add up to more than 100%?
Because of the bookmaker’s margin, called the overround. Price both sides of an even contest at -110 and each side implies 52.38%, giving a total of 104.76%. The extra 4.76% is the cushion built into the prices, and it is why the odds on offer are always a little worse than the fair odds on every side of a market.
Why do implied probabilities add up to more than 100%?
Because of the bookmaker’s margin, called the overround. Price both sides of an even contest at −110 and each side implies 52.38%, giving a total of 104.76%. The extra 4.76% is the cushion built into the prices — the reason the odds on offer are always a little worse than the fair odds on every side. A market whose implied probabilities summed to exactly 100% would have no margin in it, and bookmakers do not offer those.
Is a price with a lower implied probability better value?
Only relative to your own judgement, never on its own. A price implying 33.33% (like +200) is generous if you judge the outcome at 50%, and short if you judge it at 25% — the same price, opposite readings. The gap between the price’s implied probability and your estimate is the whole story of whether a price is generous or short. No price is good value in isolation, and no conversion creates value that the price and your judgement together do not already contain.
What is the difference between profit and payout, exactly?
Profit is stake × (decimal − 1); payout is stake × decimal. The difference between them is always exactly your stake, because the payout returns your stake along with the profit. At −150 on a $100 stake, the profit is $66.67 and the payout is $166.67 — and $166.67 − $66.67 = $100.00, your stake. If any two figures you are comparing differ by anything other than the stake, one of them was mistyped or mislabelled.
Can converting odds help me win?
No. Converting a price between American, decimal and fractional formats changes how the price is written, not what it is worth — and it does nothing to the overround built into the market. This calculator converts prices exactly so you can read them clearly and compare them honestly; it does not improve them, predict outcomes, or create an edge. Treat every price as a price for an uncertain outcome, and never stake more than you can afford to lose.
What is pari-mutuel betting?
A system, used in horse racing, in which bettors bet into a pool, the operator takes a percentage called the takeout, and the remainder is divided among the winners in proportion to their stakes. The odds are set by the pool, not by a bookmaker, and they fluctuate until betting closes. There is no bookmaker taking the other side.
Do live odds work the same as pre-match odds?
The conversion is the same, but the market is faster and the margin is wider. Live odds move continuously with the score, the time remaining, and the money, and the market suspends at moments of high uncertainty. A price taken live must be judged at the market’s speed, and the wider margin raises the win rate needed to break even.
What is a round robin bet?
A set of parlays covering the combinations of a group of selections, so that some return is paid if not all the selections win. Three selections by twos is 3 parlays; four selections by twos is 6 and by threes is 4; five selections by twos and by threes is 10 each. The total stake is the stake per parlay times the number of parlays.
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