Convert Between Fractional, Decimal and American Odds
Quick Reference
Fractional odds (8/1) are profit per stake unit; decimal odds (9.0) are total return per unit including the stake; American odds show profit on 100 staked (+800) or the stake needed to win 100 (-125). Irish sites default to fractional on racing and decimal on football — the bet is identical in any format. Implied probability is 100 divided by the decimal odds; add up a whole market and the amount over 100% is the bookmaker margin.
Frequently Asked Questions
What is 8/1 in decimal odds?
9.0. Decimal = fractional profit + 1, because decimal includes your returned stake.
What do odds of 9.0 mean?
A 10 euro stake returns 90 euro total: 80 profit plus your 10 back. Implied probability 11.1%.
Why do Irish bookmakers use fractional odds?
Racing tradition. The formats are pure notation; the bet and the payout are identical.