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Odds Converter

Convert any price between decimal, fractional, and American (moneyline) formats and read the implied probability — the break-even win rate a bet needs.

Enter as

Result
Implied probability50%
Decimal
2
American
+100
Fractional
1/1
For information only. Odds and stakes are yours to verify — bet responsibly and within your limits.

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Flamia turns these numbers into a clean, auditable ledger — auto-imported from your slips, with ROI, CLV, and risk built in.

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Odds come in three formats — decimal, fractional, and American (moneyline) — and every one describes the same price differently. This converter translates any odds into all three formats at once and shows the implied probability: the break-even win rate a bet needs to be profitable.

How odds formats relate

Decimal odds (e.g. 2.50) show your total return per unit staked, stake included. Fractional odds (3/2) show profit relative to stake. American odds show how much you win on 100 (for a favourite, how much you must stake to win 100).

Implied probability is the key number underneath all three: it is 1 divided by the decimal odds, expressed as a percentage. A price of 2.50 implies 40% — meaning a bet at those odds needs to win more than 40% of the time to be profitable.

Comparing implied probability to your own estimate of an outcome’s true chance is how you find value. If you think something is more likely than the odds imply, the bet is +EV.

Worked example

Enter decimal odds of 2.50. The converter returns +150 in American format and 3/2 in fractional format.

The implied probability is 1 ÷ 2.50 = 40%. So a bet at 2.50 breaks even if it wins exactly 40% of the time.

If your own model says the outcome wins 45% of the time, the price is in your favour — a value bet. That gap between implied and estimated probability is your edge.

Frequently asked questions

What is implied probability?
Implied probability is the chance of winning that a set of odds represents, calculated as 1 divided by the decimal odds. It is the break-even win rate: bet only when you believe the true chance is higher than the implied figure.
How do I convert American odds to decimal?
For positive American odds, decimal = (American ÷ 100) + 1. For negative odds, decimal = (100 ÷ |American|) + 1. This converter does it instantly in both directions, along with fractional and implied probability.
Which odds format is best?
Decimal is the easiest for calculating payouts and comparing value, which is why most bettors and every Flamia calculator use it. Fractional and American are largely regional conventions for the same underlying prices.

Turn an implied-probability edge into a stake with the Kelly criterion calculator.

Combining several converted prices into one ticket? Use the parlay calculator.

Comparing prices across books for a sure bet? See the arbitrage calculator.

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