Convert between decimal, fractional, and American odds formats with implied probability, payout tables, stake analysis, and a complete conversion reference chart.
Decimal odds (also called European odds) express the total payout per unit staked — a decimal odds of 2.50 means you receive $2.50 for every $1 wagered, including your original stake. This format is the most intuitive because the implied probability is simply 1 divided by the odds, and the profit multiplier is the odds minus one.
This calculator converts seamlessly between the three major odds formats used worldwide: decimal (Europe, Australia), fractional (UK, Ireland), and American/moneyline (US). Enter odds in any format, and instantly see the equivalent in all three formats alongside the implied probability, potential payout, and profit for any stake amount.
The payout table shows returns across seven common stake levels, and the conversion reference chart provides a quick-lookup grid covering odds from 1.10 to 20.00. Whether you're comparing odds across international sportsbooks, calculating expected value, or simply trying to understand what "+150" means in decimal terms, this tool handles the conversions instantly.
Comparing odds across different sportsbooks and regions requires constant conversion between formats. A bet offered at 5/2 in the UK, +250 in the US, and 3.50 in Europe are all the same — but you need a converter to verify that quickly. This calculator eliminates mental math errors and provides instant cross-format comparison.
The payout table and ROI display help you assess risk and reward at a glance. The conversion reference chart serves as a permanent reference for the most common odds ranges. Whether you're a casual bettor, a data analyst studying sports markets, or a student learning probability, this tool makes odds transparent and comprehensible.
Decimal to Implied Probability: P = 1 / decimal Decimal to Fractional: numerator = decimal − 1 Decimal to American: If decimal ≥ 2: American = +(decimal − 1) × 100 If decimal < 2: American = −100 / (decimal − 1) Fractional to Decimal: decimal = num/den + 1 American to Decimal: If positive: decimal = American/100 + 1 If negative: decimal = 100/|American| + 1 Payout = stake × decimal Profit = stake × (decimal − 1)
Result: Fractional: 3/2, American: +150, Implied: 40%, Payout: $250, Profit: $150
Decimal odds of 2.50 mean 40% implied probability (1/2.50). A $100 bet returns $250 total ($150 profit). In fractional format, that's 3/2 (win $3 for every $2 staked), and in American format, +150 (win $150 on a $100 bet).
**Decimal odds** (1.50, 2.00, 5.00) represent total return per unit staked. They're used across Europe, Australia, and increasingly worldwide. Their strength is simplicity: payout = stake × odds. **Fractional odds** (1/2, 1/1, 4/1) show profit relative to stake and have centuries of tradition in British horse racing. **American odds** (+150, -200) are based on $100 reference bets: positive means "how much you win on a $100 bet," negative means "how much you must bet to win $100."
The key to strategic betting is comparing true probability with implied probability. If a coin flip is offered at decimal 1.90 (implying 52.6%), but the true probability is 50%, the bet has negative expected value: EV = 0.50 × 0.90 - 0.50 × 1.00 = −$0.05 per dollar. The 2.6% gap is the bookmaker's edge.
In a two-outcome event, fair odds would sum to exactly 100% in implied probability. A bookmaker might offer Team A at 1.85 (54.1%) and Team B at 1.95 (51.3%), totaling 105.4%. The 5.4% overround is the bookmaker's built-in profit margin. Lower overround means better value for bettors. Exchange betting platforms like Betfair typically offer lower overround than traditional bookmakers.
You receive $1.50 for every $1.00 staked, meaning $0.50 profit per dollar. The implied probability is 66.7% (1/1.50). This represents a moderate favorite.
For positive odds like +200: divide by 100 and add 1 → 200/100 + 1 = 3.00. For negative odds like -150: divide 100 by the absolute value and add 1 → 100/150 + 1 = 1.667.
Implied probability tells you what the odds "think" the chance of winning is. If your estimated probability exceeds the implied probability, the bet has positive expected value. This is fundamental to value betting strategy.
The bookmaker's margin (vig/juice) is built into the odds. If you add implied probabilities for all outcomes in an event, they'll sum to more than 100%. The excess is the overround — typically 2-10% for major markets.
Historical convention. UK bookmakers used fractional odds for centuries. American sports betting developed its own system based on $100 reference bets. Decimal odds emerged in continental Europe and are now the global standard because they're the simplest to calculate with.
No. Decimal odds of 1.00 would mean zero profit — you just get your stake back. In practice, the minimum is slightly above 1.00 (e.g., 1.01 for an overwhelming favorite). Fractional equivalent would be 1/100.