One betting price can wear three disguises—and a tiny typo can change its meaning completely.
At one sportsbook, a selection appears at +150; elsewhere, the same price is shown as 2.50 or 3/2. All three mean a $100 stake produces $150 profit and a $250 total return, with an implied probability of 40%.
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Small reading errors have large consequences. Changing +150 to -150 raises the implied probability from 40% to 60%. Reversing 3/2 into 2/3, or treating decimal odds as profit rather than total return, similarly distorts the calculation. Odds conversion prevents those format mismatches by expressing the same price in familiar notation. It does not improve the price, uncover an edge, or turn a poor wager into a good one; it simply makes comparison and calculation safer.
Convert any quoted price instantly
Select the format of the quoted price, enter the value, and run the conversion. The calculator returns matching American, decimal, fractional, Hong Kong, Indonesian, and Malay odds, together with the market’s implied probability.
For example, American +150 converts to decimal 2.50, fractional 3/2, Hong Kong 1.50, Indonesian 1.50, Malay -0.67, and an implied probability of 40%. These are different notations for the same price—not different betting offers.
Entering odds correctly
Signs matter in formats that use them:
- American: enter
+150or-200. A positive number shows profit on a 100-unit stake; a negative number shows the stake required for 100 units of profit. - Indonesian and Malay: retain the quoted positive or negative sign, as each sign changes how the return is expressed.
- Fractional: use a slash, such as
5/2, rather than a decimal approximation. - Decimal and Hong Kong: enter standard numeric values. Decimal odds must be above
1.00; Hong Kong odds must be above0.00.
Malformed entries—such as 3//2, a zero denominator, letters, missing values, or an invalid sign—should produce an error rather than a guessed conversion. Rechecking the selected source format often resolves an apparently incorrect result.
Displayed values may differ slightly because fractions and decimals are rounded for readability. The calculator should perform its calculations at higher precision first, then round only the visible output. Consequently, converting a rounded result back into the original format can create a tiny discrepancy, even though every valid output represents the same underlying payout and implied probability.
What Each Odds Format Means
Decimal odds
The number is the total return per unit staked, including the original stake. Decimal odds are a useful starting point to understand how betting odds work.
Fractional odds
The fraction shows profit relative to stake. At 3/2, a 2-unit stake earns 3 units profit, with 5 returned overall.
American odds
Positive odds show profit from a 100-unit stake: +150 wins 150. Negative odds show the stake required to win 100: −200 requires 200.
Hong Kong odds
Hong Kong odds show profit per unit staked and equal decimal odds minus 1.00. HK 1.50 is therefore decimal 2.50.
Indonesian odds
A positive figure is profit per unit staked; +1.50 equals decimal 2.50. A negative figure is the stake needed to win one unit; −2.00 equals decimal 1.50.
Malay odds
Positive figures show profit per unit staked, while negative figures show the stake needed to win one unit. Malay +0.50 equals decimal 1.50; −0.50 equals decimal 3.00.
One price, seven expressions
Start with decimal 2.50. A winning bet returns 2.50 times the stake, including the original stake, so the profit is 1.50 times the amount wagered.
| Format | Equivalent | Interpretation |
|---|---|---|
| Decimal | 2.50 | Total return per unit staked |
| Fractional | 3/2 | Three units of profit for every two staked |
| American | +150 | 150 units of profit from a 100-unit stake |
| Hong Kong | 1.50 | Profit per unit staked |
| Indonesian | +1.50 | Positive profit ratio |
| Malay | −0.67 | Stake required per unit of profit, rounded from −0.666… |
| Implied probability | 40% | 1 ÷ 2.50 |
Nothing about the underlying price changes; only the notation does. The same wager therefore produces identical potential profit and implied probability in every row.
Positive American prices can initially look unusual. The plus sign means the quoted number is the profit on a 100-unit stake, not the total payout: +150 returns 250 units in total. The same rule applies throughout American odds conversion, while negative prices instead show how much must be staked to make 100 units of profit.
When the favorite is odds-on
Decimal 1.50 implies a 66.67% probability and returns $150 from a $100 stake: $100 principal plus $50 profit. Its equivalent prices are 1/2 fractional, −200 American, 0.50 Hong Kong, −2.00 Indonesian, and +0.50 Malay.
Compared with decimal 2.50, several signs reverse. American and Indonesian odds become negative because the stake required to win one unit of profit is now larger than that profit; Malay odds become positive. The key ratios also flip: 1/2 means one unit of profit for every two staked, while −200 means staking 200 to profit 100.
Extra care helps with fractional odds conversion. Subtract 1 from the decimal price first, giving 0.50, then express and simplify that profit ratio as 1/2. Treating 1.50 itself as the fraction can produce 3/2, which represents decimal 2.50—a substantially different price.
Odds conversion formula reference
Let D represent decimal odds. Converting each quote to decimal first keeps the sign rules manageable and provides a single route to implied probability.
Convert to decimal
- Fractional
a/b:D = 1 + (a ÷ b) - Positive American
+A:D = 1 + (A ÷ 100) - Negative American
−A:D = 1 + (100 ÷ A), using the absolute value ofA - Hong Kong
H:D = 1 + H - Positive Indonesian
+I:D = 1 + I - Negative Indonesian
−I:D = 1 + (1 ÷ |I|) - Positive Malay
+M:D = 1 + M - Negative Malay
−M:D = 1 + (1 ÷ |M|)
Convert from decimal
- Implied probability:
P = (1 ÷ D) × 100% - Hong Kong:
H = D − 1 - Indonesian: use
D − 1whenD ≥ 2; otherwise use−1 ÷ (D − 1) - Malay: use
D − 1whenD < 2; otherwise use−1 ÷ (D − 1)
For fractional odds, calculate D − 1, express the result as a fraction, then reduce it to lowest terms. For example, 1.50 − 1 = 0.50 = 1/2.
Small visual mismatches are normal when a bookmaker displays only two decimal places. A stored price such as 2.495 may appear as 2.50, while conversion from the rounded display produces a slightly different fraction or percentage. Fraction simplification can also make equivalent values look unrelated: 3/2, 6/4, and 1.5 all represent the same profit ratio.
Price, probability, and payout are different
Consider decimal odds of 2.20 with a $50 stake:
- Odds (2.20): the quoted price, expressed as a total-return multiplier.
- Implied probability (45.45%): calculated as 1 ÷ 2.20. It reflects the break-even probability before considering bookmaker margin.
- Stake ($50): the amount risked on the bet.
- Profit ($60): the winnings above the original stake: $50 × (2.20 − 1).
- Total return ($110): profit plus the returned $50 stake: $50 × 2.20.
An odds converter changes 2.20 into equivalent formats, such as fractional 6/5 or American +120. It does not calculate a wager-specific payout unless a stake is also entered. For that job, a payout calculator for a specific wager combines the odds and stake.
The distinction matters when a betting site displays “returns” or “payout.” Those figures commonly include the original stake. A returned stake is the bettor’s own money coming back, so it forms part of total return but is never counted as profit.
Conversion changes notation, not value
Equivalent prices preserve the same profit ratio and implied probability.
Decimal 2.00, 1/1, +100, HK 1.00, Indonesian +1.00, and Malay 1.00 all represent even money.
It is a price-derived estimate that usually includes bookmaker margin.
Market probabilities often total more than 100%, so the raw figure is not an independent forecast.
A meaningful comparison requires the same selection, market, and settlement rules.
Similar-looking markets may cover different outcomes or settle differently.
Reject zero, blank, malformed signs, and fractions with a zero or invalid denominator. Standard decimal odds cannot fall below 1.00; 1.00 offers no profit. Extreme prices may be valid but need extra precision. Rounded fractions are approximate, so small conversion differences are not necessarily errors.
First identify the format, enter the quoted price exactly, then normalize it to decimal odds or implied probability. Check signs and rounding. Use a payout tool only when stake-based profit and total return matter.
Conversion makes unfamiliar prices clearer. It does not remove margin, judge a market, select bets, or determine stake size.