What do decimal odds of 1.50 mean?

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.

How do I convert American odds to decimal?

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.

Why is implied probability important?

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.

What is the vig/overround?

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.

Why do different formats exist?

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.

Can decimal odds be less than 1?

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.

Decimal Odds Calculator

Convert between decimal, fractional, and American odds formats with implied probability, payout tables, stake analysis, and a complete conversion reference chart.

Input Format

Decimal Odds

Stake Amount ($)

Decimal Odds

2.500

European format

Fractional Odds

3/2

UK format (numerator/denominator)

American Odds

+150

Underdog

Implied Probability

40.00%

1 / decimal odds

Potential Payout

$250.00

On $100.00 stake

Potential Profit

$150.00

ROI: 150.0%

Probability Meter

40.0%

Payout by Stake

Stake	Payout	Profit	ROI
$10	$25.00	+$15.00	150.0%
$25	$62.50	+$37.50	150.0%
$50	$125.00	+$75.00	150.0%
$100	$250.00	+$150.00	150.0%
$200	$500.00	+$300.00	150.0%
$500	$1,250.00	+$750.00	150.0%
$1,000	$2,500.00	+$1,500.00	150.0%

Odds Conversion Reference

Decimal	Fractional	American	Implied %
1.10	1/10	-1000	90.9%
1.25	1/4	-400	80.0%
1.50	1/2	-200	66.7%
1.75	3/4	-133	57.1%
2.00	1/1	+100	50.0%
2.50	3/2	+150	40.0%
3.00	2/1	+200	33.3%
4.00	3/1	+300	25.0%
5.00	4/1	+400	20.0%
10.00	9/1	+900	10.0%
20.00	19/1	+1900	5.0%

Planning notes, formulas, and examples

About the Decimal Odds Calculator

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 quickly 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 calculator handles the conversions quickly.

When This Page Helps

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 calculator makes odds transparent and comprehensible.

How to Use the Inputs

Select your input format: decimal, fractional, American, or implied probability.
Enter the odds value in your chosen format.
Enter your stake amount to see potential payout and profit.
Use presets for common odds scenarios: even money, favorites, underdogs, long shots.
Review all three odds formats and the implied probability in the output cards.
Check the payout table for returns at various stake levels.
Use the conversion reference chart to quickly compare common odds values.

Formula used

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)

Example Calculation

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).

Tips & Best Practices

Decimal odds are the easiest to work with mathematically — multiply by stake for total payout.
To spot value, compare your estimated probability with the implied probability from the odds.
The sum of implied probabilities for all outcomes reveals the bookmaker's margin.
American odds > 0 indicate underdogs; < 0 indicate favorites. The absolute value tells you the profit or required stake per $100.
Fractional odds of "evens" (1/1) equal decimal 2.00 and American +100.
Always compare odds in the same format — decimal is recommended for mathematical clarity.

The Three Odds Systems

**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."

Expected Value and Implied Probability

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.

Understanding Overround

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.

Sources & Methodology

Last updated: March 8, 2026

Frequently Asked Questions

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.