Fractional, decimal & American odds explained

Fractional, decimal & American odds can describe exactly the same price. For example, 1/1, 2.00 & +100 all mean an ordinary winning cash bet returns the stake plus an equal amount of profit.

The difference is what each format includes in its number. Decimal odds include the stake; the other two describe the relationship between stake & profit.

What each format means

Fractional odds show profit relative to stake. At 3/2, every €2 staked produces €3 profit if the bet wins. To convert to decimal, divide the first number by the second, then add 1: 3 ÷ 2 + 1 = 2.50.

Decimal odds show the total winning return per unit staked. At 2.50, a €10 stake returns €25: the original €10 plus €15 profit.

American odds use a sign. A positive number shows profit per 100 units staked: +150 means €150 profit per €100, or €15 per €10. A negative number shows the stake corresponding to 100 units of profit: −200 means €200 for €100 profit, or €10 for €5. These are ratios, not required stake sizes.

The same price, written three ways

Equivalent prices: each row describes the same odds.

Fractional	Decimal	American
1/1	2.00	+100
1/2	1.50	−200
3/2	2.50	+150

For a €10 winning cash bet, those rows produce total returns of €20, €15 & €25 respectively. The profits are €10, €5 & €15.

Convert American odds to decimal

For a positive price, divide by 100, then add 1: +150 → 150 ÷ 100 + 1 = 2.50.

For a negative price, divide 100 by the number without its minus sign, then add 1: −200 → 100 ÷ 200 + 1 = 1.50.

These examples convert exactly. Other prices may be rounded: −110 equals 1.90909… in decimal form, often displayed as 1.91. Changing the format does not improve the price or establish an outcome’s true chance.

One quick check

Does −200 mean a winning bet has negative profit? No. The minus sign identifies the format’s stake-to-profit relationship. In the €10 example, the total return is €15 & the profit is €5.

Examples assume ordinary cash stakes before fees or tax, with a fully winning outcome. A losing cash bet loses its stake. Information only. 18+.

Sources

• Smarkets: definitions of the three odds formats
• Betfair: odds conversion table

Sources checked 7 September 2026. Examples calculated independently.

Keep learning

• How decimal odds translate into returns
• The difference between stake, return & profit