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Odds calculator: decimal, fractional, American and probability converter
Argentine sites show decimal odds, but articles and sites from other countries use fractional (3/2) and American (+150) odds. They are the same odds written another way. The converter switches between them and shows the probability each one implies.
The math
decimal = 1 + a/b
+x → 1 + x/100 · −x → 1 + 100/x
implied prob. = 1 / decimal
Convert odds
accepts 2.50 or 2.50 · 3/2 · +150 or −200
How it is calculated, step by step (with 2.50)
- Fractional: 2.50 − 1 = 1.50 = 3/2 (profit per peso)
- American, odds of 2 or more: (2.50 − 1) × 100 = +150 (profit on 100)
- American, odds below 2: 100 / (1.50 − 1) = 200, with a minus sign: −200 (what you bet to win 100)
- Implied probability: 1 / 2.50 = 0.4000 = 40.0%
- Without margin, 1.85 and 1.95: 1 / 1.85 + 1 / 1.95 = 1.0534; fair odds = 1.85 × 1.0534 = 1.95
The most common odds, in all three formats
- 1.201/5−50083.3%
- 1.501/2−20066.7%
- 1.804/5−12555.6%
- 2.001/1+10050.0%
- 2.503/2+15040.0%
- 3.002/1+20033.3%
- 4.003/1+30025.0%
- 5.004/1+40020.0%
- 10.009/1+90010.0%
Each row is the same odds in all three formats; the bar is its implied probability (1 / decimal odds). Calculated by the program.
What implied probability is
What it says
Odds of 2.50 pay $ 2,500 for every $ 1,000 bet, stake included. For that bet to be even, the result would have to happen 40.0% of the time.
What it doesn't say
It is not the real probability: it includes the betting site's margin, which is why the probabilities in one market add up to more than 100%. And no odds tell you who will win.
Remove the margin from a market
example odds: over or under 2.5 goals
Fair odds spread the margin in proportion to each probability (the simplest method; there are others). They are the odds a betting site that charges nothing would pay, not a prediction.
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