Sports Betting Odds Explained — American Odds Guide for Beginners
Every sportsbook in South Dakota displays American odds — also called moneyline or US odds. They look confusing at first (+150, -110, -3.5) but they're actually straightforward once you understand the two formats. This guide explains everything with examples.
Plus (+) Odds = Underdog
A positive number means the team is an underdog. The number tells you how much you'd win on a $100 bet.
Example: Vikings +150 means a $100 bet wins $150 in profit (plus your $100 back, for a total of $250).
Example: Twins +200 means a $50 bet wins $100 in profit.
Higher plus number = bigger underdog = bigger payout if you win.
Minus (-) Odds = Favorite
A negative number means the team is a favorite. The number tells you how much you need to bet to win $100.
Example: Chiefs -150 means you need to bet $150 to win $100 in profit.
Example: Lakers -200 means you need to bet $200 to win $100 in profit.
Bigger minus number = bigger favorite = need to bet more to win $100.
Point Spreads
Point spreads adjust for team strength. The favorite is listed with a minus number and must win by MORE than that number for the bet to cash. The underdog has a plus number and can lose by up to that amount and still cash.
Example: Vikings -3.5 vs Packers +3.5 — Vikings must win by 4+ for the spread bet to win.
The half-point (.5) eliminates "push" (tie) outcomes. Most NFL spreads use half-points.
Totals (Over/Under)
The sportsbook sets a number for combined points scored. You bet whether actual total goes Over or Under that number.
Example: Vikings/Packers total 47.5 — if final score is 24-21 (45 points), Under wins; if 27-24 (51 points), Over wins.
The Standard "Juice": -110
Most point-spread and total bets in SD are listed at -110 odds. That's the sportsbook's standard commission: you bet $110 to win $100 (or $11 to win $10, scaled). Across all bettors, the books take roughly a 4-5% edge built into the -110 pricing.
Some books occasionally offer -105 or +100 promotions on selected games — those are better value when available.
Implied Probability
Every odds price translates to an implied probability that the bookmaker thinks the outcome will happen. Quick formulas:
- Negative odds: probability = |odds| / (|odds| + 100) — e.g., -150 → 150/250 = 60% implied
- Positive odds: probability = 100 / (odds + 100) — e.g., +150 → 100/250 = 40% implied
- -110 implies 52.4% — the sportsbook needs you to win less than that to break even
Key Takeaways
- Plus odds = underdog; the number is your profit on a $100 bet
- Minus odds = favorite; the number is what you must bet to win $100
- Point spreads use half-points to prevent ties
- -110 is the standard "juice" and contains the sportsbook's edge
- Convert odds to implied probability to identify value bets