Conversion formulas
Fractional to decimal: numerator ÷ denominator + 1, so 3/2 = 2.50. American to decimal: +150 means 150 ÷ 100 + 1 = 2.50; -200 means 100 ÷ 200 + 1 = 1.50. Decimal to American: at 2.00 or more, (decimal - 1) × 100; below 2.00, -100 ÷ (decimal - 1).
Implied probability = 1 ÷ decimal odds. 2.50 implies 40%, 1.50 implies 66.67%. If you think the real chance is higher than the implied one, the price favours you; if not, it does not.
Return and profit
Total return = stake × decimal odds; profit = return - stake. A 10 stake at 2.50 returns 25, of which 15 is profit. Fractional odds show the profit directly: 3/2 pays 3 for every 2 staked.
Bookmaker margin
Add up 1 ÷ odds for every outcome of a market. Without a margin the sum is exactly 100%; whatever is above it is the bookmaker's edge. Two outcomes at 1.90 give 52.63% + 52.63% = 105.26%, a margin of 5.26%. Fair odds remove it proportionally: here both become 2.00.
A lower margin means more of every stake comes back on average. Comparing the margin of the same market at several bookmakers is the quickest way to see who prices it more generously.
Why there are no picks here
We review casinos, not sportsbooks, so the converter recommends no bookmaker. Check that a betting site is licensed in your country before you deposit.