Table of Contents
What Are Decimal Odds?
Decimal odds represent total return per unit staked, including the stake. Odds of 2.50 mean a $1 bet returns $2.50 ($1.50 profit + $1 stake). They are the most popular format in Europe, Canada, and Australia due to their simplicity and ease of calculation.
Favorites have odds between 1.01-1.99; underdogs have odds above 2.00. Even chances are 2.00. The implied probability is simply 1/odds, making comparison between bets straightforward.
Conversions
Format Comparison
| Decimal | Fractional | American | Prob |
|---|---|---|---|
| 1.50 | 1/2 | -200 | 66.7% |
| 2.00 | 1/1 | +100 | 50% |
| 3.00 | 2/1 | +200 | 33.3% |
| 5.00 | 4/1 | +400 | 20% |
Value Bets
A value bet exists when your estimated true probability exceeds the implied probability from odds. If odds are 3.00 (33.3% implied) but you estimate 40% true probability, the bet has positive expected value over time.
Frequently Asked Questions
Why do probabilities sum above 100%?
The excess is the bookmaker's margin (overround/vig). Lower overround means fairer odds for bettors.
Lowest possible decimal odds?
Odds approach but never equal 1.00. Most bookmakers cap minimum odds around 1.01 for near-certain outcomes.
Converting American to decimal?
Positive: (American/100)+1. Negative: (100/|American|)+1. E.g., +150 = 2.50, -200 = 1.50.