Odds, probability and the margin

Football odds are just a price, and every price hides a probability and a fee. Once you can see both, the three-way market stops looking arbitrary.

From odds to implied probability

Decimal odds convert with one division: 1 ÷ decimal odds.

• 1.50 → 1 ÷ 1.50 ≈ 67%.
• 4.20 → 1 ÷ 4.20 ≈ 24%.
• 6.50 → 1 ÷ 6.50 ≈ 15%.

Short odds = high implied probability (a favourite); long odds = low (an underdog).

The three-way margin

Add the implied probabilities of 1, X and 2 together and you'll get more than 100%. Using the prices above: 67% + 24% + 15% = 106%. That extra ~6% is the bookmaker margin (the vig, juice or overround) — the book's built-in edge across all three outcomes. Three-way markets often carry a slightly fatter margin than two-way ones simply because there are more outcomes to load.

Why it matters

The margin is the cost of betting, and it means the "true" probabilities are a little lower than the raw implied numbers. Comparing prices across bookmakers — exactly what FinalSkore's odds comparison helps with — finds the lines with the smallest margin, so more of any edge stays with you.