Betting Odds Converter
How it works
Whichever format you enter is first turned into decimal odds — the multiple a stake becomes, stake included — because everything else is easiest to derive from that one number. A fractional 5/2 is (5 ÷ 2) + 1 = 3.5; American +150 is (150 ÷ 100) + 1 = 2.5; American -150 is (100 ÷ 150) + 1 ≈ 1.667. Decimal odds under 1 are rejected, since a price of 1.0 or below offers no potential return above the stake in any format.
From decimal odds, implied probability is 1 ÷ decimalOdds; American odds run the opening formula backwards; and the fractional figure rounds decimalOdds − 1 to the nearest hundredth and reduces that to a simple fraction, which is why it is an approximation rather than an exact reverse conversion.
Frequently asked questions
What does "implied probability" mean?
The break-even chance of that outcome, according to the odds themselves — the price at which neither side of the bet has an edge. It ignores the bookmaker's margin entirely, which is why real bookmaker odds across a full market usually imply somewhat MORE than 100% total probability once you add every outcome up; a single price on its own carries no information about the rest of that margin.
How does the sign of American odds work?
Positive American odds (+150) mark the underdog price and read as profit on a $100 stake — +150 means a $100 bet profits $150. Negative American odds (-150) mark the favorite price and read as stake needed to profit $100 — -150 means you'd need to stake $150 to profit $100. Both sides describe the same thing decimal odds do, just as a signed shorthand instead of a single number above or below 2.0.
Why is the fractional odds figure shown here an approximation?
A fraction is just one whole number over another, and an arbitrary decimal odds value — 2.734, say — rarely lands on a clean one. This tool rounds to the nearest whole percent of the decimal odds and reduces that to a reasonably simple fraction, which is usually close to but not always identical to how a bookmaker would actually quote it.