What Is an Odds Converter?
An odds converter instantly transforms betting odds between the three main formats:
- Decimal odds (2.50) - Used in Europe, Australia, Canada
- Fractional odds (3/2) - Traditional UK format
- American odds (+150) - Used in the United States
Enter odds in any format and see the equivalent in all other formats, plus the implied probability.
Why Convert Odds?
Different Regions Use Different Formats
| Region | Common Format | Example |
|---|---|---|
| Europe | Decimal | 2.50 |
| UK/Ireland | Fractional | 3/2 |
| USA | American | +150 |
| Australia | Decimal | 2.50 |
| Asia | Decimal/Hong Kong | 2.50 / 1.50 |
Comparing Bookmakers
When shopping for the best odds across bookmakers, you need to compare like-with-like. Converting all odds to decimal makes comparison easy.
Odds Conversion Formulas
Decimal to Fractional
Fractional = (Decimal - 1) / 1
Example: Decimal 3.50
- Fractional = (3.50 - 1) / 1 = 2.5/1 = 5/2
Decimal to American
If Decimal ≥ 2.00:
American = (Decimal - 1) × 100
If Decimal < 2.00:
American = -100 / (Decimal - 1)
Examples:
- Decimal 2.50: (2.50 - 1) × 100 = +150
- Decimal 1.50: -100 / (1.50 - 1) = -200
Fractional to Decimal
Decimal = (Numerator / Denominator) + 1
Example: Fractional 5/2
- Decimal = (5/2) + 1 = 2.5 + 1 = 3.50
Fractional to American
If Numerator ≥ Denominator (odds against):
American = (Numerator / Denominator) × 100
If Numerator < Denominator (odds on):
American = -100 × (Denominator / Numerator)
Examples:
- 5/2: (5/2) × 100 = +250
- 1/2: -100 × (2/1) = -200
American to Decimal
Positive American (+):
Decimal = (American / 100) + 1
Negative American (-):
Decimal = (100 / |American|) + 1
Examples:
- +200: (200/100) + 1 = 3.00
- -150: (100/150) + 1 = 1.67
American to Fractional
Positive American (+):
Fractional = American / 100
Negative American (-):
Fractional = 100 / |American|
Examples:
- +250: 250/100 = 5/2
- -200: 100/200 = 1/2
Complete Odds Conversion Table
| Decimal | Fractional | American | Implied Probability |
|---|---|---|---|
| 1.10 | 1/10 | -1000 | 90.9% |
| 1.20 | 1/5 | -500 | 83.3% |
| 1.25 | 1/4 | -400 | 80.0% |
| 1.33 | 1/3 | -300 | 75.0% |
| 1.40 | 2/5 | -250 | 71.4% |
| 1.50 | 1/2 | -200 | 66.7% |
| 1.57 | 4/7 | -175 | 63.6% |
| 1.67 | 2/3 | -150 | 60.0% |
| 1.73 | 8/11 | -137 | 57.8% |
| 1.80 | 4/5 | -125 | 55.6% |
| 1.83 | 5/6 | -120 | 54.5% |
| 1.91 | 10/11 | -110 | 52.4% |
| 2.00 | 1/1 (Evens) | +100 | 50.0% |
| 2.10 | 11/10 | +110 | 47.6% |
| 2.20 | 6/5 | +120 | 45.5% |
| 2.25 | 5/4 | +125 | 44.4% |
| 2.38 | 11/8 | +138 | 42.0% |
| 2.50 | 3/2 | +150 | 40.0% |
| 2.63 | 13/8 | +163 | 38.0% |
| 2.75 | 7/4 | +175 | 36.4% |
| 3.00 | 2/1 | +200 | 33.3% |
| 3.25 | 9/4 | +225 | 30.8% |
| 3.50 | 5/2 | +250 | 28.6% |
| 4.00 | 3/1 | +300 | 25.0% |
| 4.50 | 7/2 | +350 | 22.2% |
| 5.00 | 4/1 | +400 | 20.0% |
| 6.00 | 5/1 | +500 | 16.7% |
| 7.00 | 6/1 | +600 | 14.3% |
| 8.00 | 7/1 | +700 | 12.5% |
| 9.00 | 8/1 | +800 | 11.1% |
| 10.00 | 9/1 | +900 | 10.0% |
| 11.00 | 10/1 | +1000 | 9.1% |
| 13.00 | 12/1 | +1200 | 7.7% |
| 17.00 | 16/1 | +1600 | 5.9% |
| 21.00 | 20/1 | +2000 | 4.8% |
| 26.00 | 25/1 | +2500 | 3.8% |
| 34.00 | 33/1 | +3300 | 2.9% |
| 51.00 | 50/1 | +5000 | 2.0% |
| 101.00 | 100/1 | +10000 | 1.0% |
Understanding Each Format
Decimal Odds
How to read: The number shows total return per unit staked.
| Odds | $10 Stake | Total Return | Profit |
|---|---|---|---|
| 1.50 | $10 | $15 | $5 |
| 2.00 | $10 | $20 | $10 |
| 3.00 | $10 | $30 | $20 |
Why use decimal:
- Easiest to calculate returns
- No negative numbers
- Clear at a glance which odds are higher
Fractional Odds
How to read: Profit you’ll win relative to stake.
| Odds | Meaning |
|---|---|
| 5/1 | Win $5 for every $1 staked |
| 2/1 | Win $2 for every $1 staked |
| 1/1 | Win $1 for every $1 staked (Evens) |
| 1/2 | Win $1 for every $2 staked |
| 1/5 | Win $1 for every $5 staked |
Common fractional odds:
- Odds against (numerator > denominator): 5/2, 3/1, 10/1
- Evens: 1/1
- Odds on (numerator < denominator): 1/2, 4/9, 1/10
American Odds
How to read:
- Positive (+): Profit on a $100 stake
- Negative (-): Stake needed to win $100 profit
| Odds | Meaning |
|---|---|
| +200 | $100 stake wins $200 profit |
| +100 | $100 stake wins $100 profit (Evens) |
| -100 | $100 stake wins $100 profit (also Evens) |
| -150 | $150 stake wins $100 profit |
| -300 | $300 stake wins $100 profit |
Key insight:
- Positive = underdog (less than 50% implied probability)
- Negative = favorite (more than 50% implied probability)
Implied Probability Calculation
From Decimal Odds
Probability = (1 / Decimal) × 100%
Example: 2.50 decimal
- Probability = (1 / 2.50) × 100 = 40%
From Fractional Odds
Probability = Denominator / (Numerator + Denominator) × 100%
Example: 3/2 fractional
- Probability = 2 / (3 + 2) × 100 = 40%
From American Odds
Positive (+):
Probability = 100 / (American + 100) × 100%
Negative (-):
Probability = |American| / (|American| + 100) × 100%
Examples:
- +150: 100 / (150 + 100) × 100 = 40%
- -200: 200 / (200 + 100) × 100 = 66.7%
Quick Mental Conversions
Decimal to American (Approximations)
| Decimal | American | Easy Rule |
|---|---|---|
| 1.50 | -200 | Divide 100 by (decimal - 1), make negative |
| 2.00 | +100 | Evens is always +100 or -100 |
| 2.50 | +150 | Multiply (decimal - 1) by 100 |
| 3.00 | +200 | Same formula |
| 4.00 | +300 | Same formula |
Common Fractional to Decimal
| Fractional | Decimal | Memory Tip |
|---|---|---|
| Evens (1/1) | 2.00 | Double your money |
| 6/4 | 2.50 | Two and a half |
| 2/1 | 3.00 | Triple your money |
| 3/1 | 4.00 | Quadruple |
| 4/1 | 5.00 | Five times |
Practical Examples
Example 1: Comparing Bookmakers
You find the same bet at three bookmakers:
- Bookmaker A: 5/2 (fractional)
- Bookmaker B: +245 (American)
- Bookmaker C: 3.40 (decimal)
Convert all to decimal:
- 5/2 = 2.5 + 1 = 3.50
- +245 = 2.45 + 1 = 3.45
- 3.40 = 3.40
Best odds: Bookmaker A at 3.50
Example 2: Understanding Line Movement
Opening odds: -150 (American) Current odds: -130 (American)
Convert to decimal to see the change:
- -150 = 1.67 decimal
- -130 = 1.77 decimal
The odds have drifted (increased) by 0.10 decimal, meaning implied probability dropped from 60% to 56.5%.
Example 3: Calculating Combined Odds
Parlay with American odds: -110, +150, -130
Convert to decimal first:
- -110 = 1.91
- +150 = 2.50
- -130 = 1.77
Multiply: 1.91 × 2.50 × 1.77 = 8.45 combined decimal odds
Convert back to American: (8.45 - 1) × 100 = +745
Frequently Asked Questions
Which odds format is best?
Decimal is easiest for calculations. Use whatever your bookmaker shows, but convert to decimal when comparing across different books.
Why are American odds so confusing?
They were designed around $100 bets, which made sense historically. The positive/negative split indicates favorites vs underdogs instantly, which some bettors prefer.
Are Evens +100 or -100?
Both mean the same thing - you win your stake back as profit. Some books show +100, others -100, both are correct for 50% implied probability.
Do the odds affect probability?
Odds reflect bookmakers’ estimates of probability, but include a margin. True probability may differ from implied probability due to the bookmaker’s edge.
How do I convert Hong Kong odds?
Hong Kong odds show profit only (like fractional but as decimal). Add 1 to get standard decimal odds. HK 1.50 = Decimal 2.50.
What about Indonesian and Malay odds?
Indonesian odds work like American but divided by 100. Malay odds use a -1 to +1 scale. Both are less common but our converter handles all major formats.
Start Converting Odds
Use our free odds converter above to:
- Enter odds in any format
- Instantly see conversions to all other formats
- View the implied probability
- Compare odds from different sources easily
The converter handles all the math so you can focus on finding value and making informed bets.