Calculator Inputs
Enter both moneyline prices to estimate implied probability, fair probability, payout, value, and optional model-driven edge.
Example Data Table
This example shows how bookmaker margin changes the fair win rate after removing the vig from both listed sides.
| Side | Moneyline | Implied Probability | No-Vig Probability | Profit on $100 Stake |
|---|---|---|---|---|
| Lions | +135 | 42.55% | 41.18% | $135.00 |
| Sharks | -155 | 60.78% | 58.82% | $64.52 |
Formula Used
Core Moneyline Formulas
Positive odds implied probability:
Implied Probability = 100 ÷ (Odds + 100)
Negative odds implied probability:
Implied Probability = |Odds| ÷ (|Odds| + 100)
Decimal odds:
Positive: 1 + (Odds ÷ 100)
Negative: 1 + (100 ÷ |Odds|)
Value and Fair Price Formulas
No-vig probability:
Side Probability ÷ Sum of Both Implied Probabilities
Expected value:
(Projected Win Rate × Profit) − (Loss Rate × Stake)
Kelly fraction:
((b × p) − q) ÷ b, where b = decimal odds − 1
How to Use This Calculator
- Enter the names of both teams or players.
- Add each side’s American moneyline odds.
- Choose the side you want to analyze for stake-based outputs.
- Enter your stake and optional bankroll for Kelly sizing.
- Add your projected win rates if you want value and EV metrics.
- Submit the form to show results above the calculator.
- Use the CSV or PDF buttons to save the result summary.
Frequently Asked Questions
1. What does moneyline probability mean?
Moneyline probability is the win rate implied by sportsbook odds. It shows the percentage chance the market assigns to a team or player winning outright.
2. Why are implied and no-vig probabilities different?
Implied probability includes the bookmaker margin. No-vig probability removes that margin by normalizing both sides, giving a cleaner estimate of fair market expectations.
3. What is bookmaker margin in this calculator?
Bookmaker margin is the total of both implied probabilities minus 100%. It represents the built-in sportsbook edge across the two outcomes.
4. When should I use projected probabilities?
Use projected probabilities when you have your own model or handicap. They allow the calculator to estimate expected value, betting edge, and Kelly-based stake guidance.
5. What does edge vs market show?
Edge vs market compares your projected win rate to the sportsbook implied probability. A positive edge suggests your projection is stronger than the listed price.
6. Is Kelly staking always recommended?
Not always. Full Kelly can be aggressive and volatile. Many bettors use half Kelly or smaller fractions to reduce drawdowns while still sizing by edge.
7. Can both sides have negative odds?
Yes. In tightly priced markets, both sides can be negative. The calculator still works because it converts each price independently before removing the margin.
8. What stake does profit on stake use?
Profit on stake uses the stake value you entered in the form. Total return adds the original stake back to that projected profit.