Decimal Odds

Decimal odds are the format used in most of the world outside the US. A single number — like 1.91 or 3.50 — represents the total payout per $1 staked. They’re easier to math on than American odds, which is why parlay calculators and pricing models lean on them.

How to read decimal odds

The number IS the multiplier. Bet $10 at decimal odds of 2.50 → total payout $25 ($15 profit, $10 stake returned).

• 2.00 — even money. $10 returns $20 ($10 profit).
• 1.50 — heavy favorite. $10 returns $15 ($5 profit).
• 1.91 — the standard -110 vig line. $10 returns $19.10 ($9.10 profit).
• 3.00 — 2-to-1 underdog. $10 returns $30 ($20 profit).
• 6.00 — long underdog. $10 returns $60 ($50 profit).

Converting from American

• Positive American: decimal = (american / 100) + 1. So +150 → 2.50.
• Negative American: decimal = (100 / |american|) + 1. So -110 → 1.91.

Implied probability

probability = 1 / decimal odds.

• 1.50 → 66.7%
• 2.00 → 50.0%
• 3.00 → 33.3%
• 6.00 → 16.7%

Why parlays use decimal

Parlay payouts are decimal odds multiplied together. Three legs at 1.91 → 1.91 × 1.91 × 1.91 ≈ 6.97. American odds don’t multiply directly, which is why every parlay calculator converts everything to decimal first, multiplies, and converts back.