Bettors see the same game priced at -110 on one board, 1.91 on another, and 10/11 somewhere else, and stall out trying to figure out if any of those numbers are actually better. Without converting them to a common format, there’s no way to know, and a bettor can end up taking a worse number just because it was posted in a format they read faster.
This tool takes any odds format and returns the other two, along with the implied probability and the payout on a chosen stake. The number that matters is the implied probability and the total payout, since those are what decide whether a price is worth taking or worth shopping elsewhere.
Enter the odds first, in whatever format they were quoted: American (like -110 or +150), decimal (like 2.5), or fractional (like 5/2). Then enter the stake, the dollar amount being risked on that price.
The result shows the same price written all three ways: American, decimal, and fractional. Below that sits the implied probability, the chance that price bakes in, followed by the profit on the stake and the total payout, which is the stake plus that profit.
Converting American odds to decimal depends on the sign. Positive odds are divided by 100 and 1 is added. Negative odds take 100, divide it by the odds with the sign stripped off, then add 1. For -110, that’s 100 divided by 110, plus 1, which comes out to 1.909.
Implied probability is 1 divided by the decimal odds. For 1.909, that’s 52.4%, the chance the price implies for that side to win. Profit on the stake is the stake times the decimal minus 1. On a $100 stake at 1.909, that’s 100 times 0.909, or $90.91. Add that to the $100 stake and the total payout is $190.91.
Fractional odds come from the same decimal minus 1, reduced. For 1.909, that reduces to 10/11, which is the traditional way -110 has always been quoted at the counter.
This matters most when a bettor is comparing the same bet across different books that quote in different formats, or trying to judge whether a number like +145 is actually better than -140 somewhere else. Converting both to decimal or to implied probability puts them on the same scale.
A common mistake is comparing American odds directly across the zero line, treating +150 and -150 as mirror opposites when they aren’t. Another is ignoring that implied probability includes the book’s built-in edge, so two sides of the same game will add up to more than 100%.
A sharp bettor converts every price to implied probability before comparing it to their own estimate of the true chance. If the implied probability is lower than what they think the real chance is, the price has value. If it’s higher, the number isn’t worth the risk, no matter how big the payout looks.
What does -110 pay on a $100 bet? It pays $90.91 in profit, for a total payout of $190.91, since -110 converts to decimal odds of 1.909.
Why do the implied probabilities on both sides of a bet add up to more than 100%? Because the book prices in a margin on top of the true chance of each outcome, so the two implied probabilities together will run higher than 100%, with the gap representing that margin.
How is decimal converted to fractional? Take the decimal odds, subtract 1, and reduce that number to a fraction. A decimal of 1.909 reduces to 10/11.
Is decimal or American easier for comparing two prices? Decimal tends to be simpler since it’s one continuous scale with no sign change at even money, but implied probability works for any format and is the number that actually decides whether a price is worth taking.