Sports Predictor includes OddsConverter, a static utility class in betting_math.py that converts between the three most common betting odds formats. No instantiation is needed — call each method directly on the class.
betting_math.py lives inside the Betting and Parlay Engine/ directory (directory name contains spaces). To import it, add the directory to your Python path first:import sys
sys.path.append("Betting and Parlay Engine")
from betting_math import OddsConverter
| Format | Example | Description |
|---|
| American (moneyline) | +150, -200 | Positive = underdog (profit per 100wagered);negative=favorite(amounttowagertoprofit100) |
| Decimal | 2.5, 1.5 | Total return per $1 wagered, including stake |
| Implied probability | 0.4, 0.667 | The bookmaker’s assessed likelihood of an outcome, expressed as a value between 0 and 1 |
Methods
american_to_decimal
american_to_probability
decimal_to_american
decimal_to_probability
Convert American (moneyline) odds to decimal odds.American odds value. Positive for underdogs (e.g. +150), negative for favorites (e.g. -200). Cannot be 0.
float — decimal oddsFormula:
- If
american > 0: (american / 100) + 1
- If
american < 0: (100 / abs(american)) + 1
Raises: ValueError if american == 0from betting_math import OddsConverter
OddsConverter.american_to_decimal(150) # → 2.5
OddsConverter.american_to_decimal(-200) # → 1.5
Convert American odds to implied probability.American odds value. Positive for underdogs, negative for favorites. Cannot be 0.
float between 0 and 1Formula:
- If
american > 0: 100 / (american + 100)
- If
american < 0: abs(american) / (abs(american) + 100)
Raises: ValueError if american == 0from betting_math import OddsConverter
OddsConverter.american_to_probability(150) # → 0.4
OddsConverter.american_to_probability(-200) # → 0.6667
Convert decimal odds back to American odds.Decimal odds. Must be greater than 1.
float — American oddsFormula:
- If
decimal >= 2.0: (decimal - 1) * 100
- If
decimal < 2.0: -100 / (decimal - 1)
Raises: ValueError if decimal <= 1from betting_math import OddsConverter
OddsConverter.decimal_to_american(2.5) # → 150.0
OddsConverter.decimal_to_american(1.5) # → -200.0
Convert decimal odds to implied probability.Decimal odds. Must be greater than 1.
float between 0 and 1 — equal to 1 / decimalRaises: ValueError if decimal <= 1from betting_math import OddsConverter
OddsConverter.decimal_to_probability(2.5) # → 0.4
OddsConverter.decimal_to_probability(1.5) # → 0.6667
Complete example
from betting_math import OddsConverter
american_odds = -200
# Convert to all formats
decimal = OddsConverter.american_to_decimal(american_odds)
probability = OddsConverter.american_to_probability(american_odds)
print(f"American: {american_odds}")
print(f"Decimal: {decimal}") # 1.5
print(f"Probability: {probability:.3f}") # 0.667
# Convert back from decimal
back_to_american = OddsConverter.decimal_to_american(decimal)
print(f"Back to American: {back_to_american}") # -200.0
What implied probability means
Implied probability is the likelihood of an outcome as priced into the odds by a sportsbook. A line of -200 implies the bookmaker believes the favorite wins roughly 66.7% of the time.
Sportsbooks build a margin (the “vig” or “juice”) into their lines, so the sum of implied probabilities across all outcomes in a market typically exceeds 1.0. When comparing model probabilities against bookmaker odds, keep this overround in mind.