Converting Odds to Implied Probability
Your break-even probability is the win rate you need to have EV = 0. It's the sportsbook's "price tag" expressed as a probability.
Understanding this conversion is essential because it tells you the minimum accuracy you need to be profitable on any bet.
The Formulas
Negative Odds to Implied Probability
Break-even = |odds| / (|odds| + 100)=ABS(A2)/(ABS(A2)+100)Positive Odds to Implied Probability
Break-even = 100 / (odds + 100)=100/(A2+100)Worked Examples
Example 1: -110 Odds (Standard Juice)
Break-even = 110 / (110 + 100)
Break-even = 110 / 210
Break-even = 52.38% (≈52.4%)
Example 2: +150 Odds (Underdog)
Break-even = 100 / (150 + 100)
Break-even = 100 / 250
Break-even = 40.0%
Example 3: -200 Odds (Heavy Favorite)
Break-even = 200 / (200 + 100)
Break-even = 200 / 300
Break-even = 66.7%
Key Insight
Implied probability is the sportsbook's "price tag" in probability form. If you can't beat that number, you can't beat the bet.
Complete Reference Table
| American Odds | Break-Even % | You Must Win... |
|---|---|---|
| +300 | 25.0% | 1 in 4 bets |
| +200 | 33.3% | 1 in 3 bets |
| +150 | 40.0% | 2 in 5 bets |
| +120 | 45.5% | ~1 in 2 bets |
| +110 | 47.6% | ~1 in 2 bets |
| +100 | 50.0% | 1 in 2 bets |
| -110 | 52.4% | ~11 in 21 bets |
| -120 | 54.5% | ~6 in 11 bets |
| -130 | 56.5% | ~13 in 23 bets |
| -150 | 60.0% | 3 in 5 bets |
| -170 | 63.0% | ~2 in 3 bets |
| -200 | 66.7% | 2 in 3 bets |
| -250 | 71.4% | ~5 in 7 bets |
| -300 | 75.0% | 3 in 4 bets |
Excel Formula for Any Odds
Use this universal formula in Excel (with odds in cell A2):
Universal Odds Converter
IF odds < 0: |odds|/(|odds|+100), ELSE: 100/(odds+100)=IF(A2<0, ABS(A2)/(ABS(A2)+100), 100/(A2+100))Tip
Build this into a spreadsheet and keep it open whenever you're betting. Type in the odds, get the break-even percentage instantly.
Why This Matters
When you see a prop at -150, you now know instantly:
- Break-even is 60% — you need to win 3 out of 5 bets just to break even
- Your estimate must exceed 60% — if you think it's 58%, pass
- The edge is the gap — if you think it's 65%, your edge is 5 percentage points
This simple conversion is the foundation of every betting decision. Master it, and you'll never make a bet without knowing exactly what you're up against.
Use the Vig Calculator
Calculate implied probability and vig for any odds:
Vig Calculator
Try the interactive calculator for this concept
📝 Exercise
Instructions
Practice converting odds to implied probability.
What is the break-even percentage for -140 odds?
What is the break-even percentage for +180 odds?
You see a prop at -200. Your model says it hits 70% of the time. Is this +EV?