How to Read Betting Odds: American, Decimal & Implied Probability

Understanding betting odds is fundamental to sports betting. Odds tell you two things: how much you can win and what the sportsbook thinks the probability of an outcome is.

American Odds (Moneyline)

American odds are the most common format in the US. They come in two flavors:

Positive Odds (+150, +200, etc.)

Positive odds show how much you'd win on a $100 bet. If the odds are +150, a $100 bet would return $150 in profit (plus your $100 back).

Negative Odds (-110, -150, etc.)

Negative odds show how much you need to bet to win $100. If the odds are -110, you'd need to wager $110 to win $100.

The standard "vig" (juice): Most prop bets are listed at -110 on both sides. This is the sportsbook's margin — you're paying $110 to win $100 either way. The book makes money regardless of the outcome.

Implied Probability

Every set of odds implies a probability. This is what the sportsbook thinks the chance of each outcome is (including their margin).

Converting American odds to implied probability:

• -Negative odds: Implied Probability = |Odds| / (|Odds| + 100)
• -Positive odds: Implied Probability = 100 / (Odds + 100)

Examples:

• --110 odds → 110 / (110 + 100) = 52.4% implied probability
• -+150 odds → 100 / (150 + 100) = 40.0% implied probability

Why This Matters for Betting

The gap between the implied probability (what the book thinks) and the true probability (what actually should happen) is where your edge lives.

If BetBlum's model says a player has a 60% chance of going OVER his points line, but the odds imply only 52.4%, you have a 7.6% edge. Over hundreds of bets, that edge compounds into real profit.

Finding Value in Odds

BetBlum calculates the implied probability for every prop and compares it to our 15-layer model's probability estimate. You see the edge and expected value on every single pick — so you always know if the odds are in your favor.

Try BetBlum free for 48 hours and see the math behind every prop.