TL;DR — Sports betting means wagering money on the outcome of sporting events. Odds tell you the payout and implied probability. The sportsbook takes a cut (the vig) on every bet. Long-term profitability requires finding situations where the odds are in your favor (+EV). AI betting bots do this faster and more consistently than humans.
How Sports Betting Works
Sports betting is straightforward: you place a wager on the outcome of a sporting event. If you’re right, you get paid. If you’re wrong, you lose your stake.
The sportsbook sets the odds. The odds determine two things: the implied probability of each outcome and how much you get paid if you win. Understanding odds is the single most important skill in sports betting.
How to Read Betting Odds
Three odds formats exist worldwide. You’ll encounter all of them.
American Odds (Moneyline Odds)
The standard in the US. Uses + and - notation.
Negative odds (-) = Favorite
- -200 means: bet $200 to win $100 profit
- The bigger the negative number, the heavier the favorite
- Implied probability: 200 / (200 + 100) = 66.7%
Positive odds (+) = Underdog
- +150 means: bet $100 to win $150 profit
- The bigger the positive number, the bigger the underdog
- Implied probability: 100 / (150 + 100) = 40.0%
AMERICAN ODDS QUICK REFERENCE
─────────────────────────────────────────────────
Odds │ Bet $100 │ Profit │ Implied Prob
─────────┼────────────┼──────────┼──────────────
-500 │ Win $20 │ $20 │ 83.3%
-300 │ Win $33 │ $33 │ 75.0%
-200 │ Win $50 │ $50 │ 66.7%
-150 │ Win $67 │ $67 │ 60.0%
-110 │ Win $91 │ $91 │ 52.4%
+100 │ Win $100 │ $100 │ 50.0%
+110 │ Win $110 │ $110 │ 47.6%
+150 │ Win $150 │ $150 │ 40.0%
+200 │ Win $200 │ $200 │ 33.3%
+300 │ Win $300 │ $300 │ 25.0%
+500 │ Win $500 │ $500 │ 16.7%
─────────────────────────────────────────────────
Decimal Odds
Standard in Europe, Australia, and most prediction markets. Simpler math.
- 2.50 means: every $1 bet returns $2.50 total (including your stake), so profit is $1.50
- 1.50 means: every $1 bet returns $1.50 total, profit is $0.50
- Implied probability: 1 / decimal odds. So 2.50 = 1/2.50 = 40.0%
Fractional Odds
Traditional in the UK. Written as fractions.
- 3/1 (read “three to one”) means: bet $1, win $3 profit
- 1/4 means: bet $4, win $1 profit
- Implied probability: denominator / (numerator + denominator). So 3/1 = 1/4 = 25.0%
Converting Between Formats
| American | Decimal | Fractional | Implied Prob |
|---|---|---|---|
| -200 | 1.50 | 1/2 | 66.7% |
| -110 | 1.91 | 10/11 | 52.4% |
| +100 | 2.00 | 1/1 (evens) | 50.0% |
| +150 | 2.50 | 3/2 | 40.0% |
| +300 | 4.00 | 3/1 | 25.0% |
For a deeper dive on how probability maps between prediction market prices and sportsbook odds, see how prediction market odds work.
Every Bet Type Explained
Moneyline
The simplest bet. Pick who wins.
NBA — March 8, 2026
Lakers +145
Celtics -170
Bet on the Lakers at +145: if they win, a $100 bet pays $145 profit. Bet on the Celtics at -170: you need to bet $170 to win $100 profit. The Celtics are the favorite.
No point spreads, no conditions. Your team wins = you win.
Point Spread (Spread Betting)
The spread handicaps the favorite to create a roughly even contest.
NFL — Week 12
Chiefs -7.5 (-110)
Bears +7.5 (-110)
- Chiefs -7.5: The Chiefs must win by 8+ points for this bet to cash.
- Bears +7.5: The Bears can lose by up to 7 points and the bet still wins.
The half-point (.5) eliminates ties (pushes). Both sides typically have the same odds (-110) because the spread is designed to attract equal action.
Spread betting is the most popular bet type in football and basketball because it makes lopsided matchups interesting. A 20-point favorite is boring on the moneyline (-2000). On the spread (-14.5), it’s a real question.
Totals (Over/Under)
Bet on the combined score of both teams.
NFL — Chiefs vs Bears
Over 44.5 (-110)
Under 44.5 (-110)
If the final score is Chiefs 31, Bears 17 (total: 48), the Over wins. If it’s Chiefs 20, Bears 13 (total: 33), the Under wins.
Totals are popular because you don’t need to pick a winner — just whether the game will be high-scoring or defensive.
Parlays
A parlay combines multiple bets into one. All legs must win for the parlay to pay. The upside: much higher payouts. The downside: much lower win probability.
3-Leg Parlay Example:
Leg 1: Chiefs -7.5 (-110) ✓
Leg 2: Lakers ML (+145) ✓
Leg 3: Over 44.5 (NFL) (-110) ✗
Result: LOSS (all legs must hit)
A 3-leg parlay at -110 per leg pays roughly 6:1. A 5-leg parlay pays roughly 20:1. The math looks attractive until you realize the expected value is worse than betting each leg separately. The sportsbook’s edge compounds with each leg.
Rule for beginners: Parlays are entertainment, not strategy. The vig compounds exponentially. If you parlay, stick to 2-3 legs maximum.
Props (Proposition Bets)
Bets on specific events within a game, not the final outcome.
- “Patrick Mahomes over 285.5 passing yards” (-115)
- “LeBron James to score first basket” (+400)
- “Total strikeouts by [pitcher] over 7.5” (-120)
Props are where AI agents excel — there are thousands of prop markets per day, and sportsbooks often set lines with less precision than main markets. This creates more opportunities for edges. See our guide on sports betting arbitrage bots for how agents exploit prop markets.
Futures
Long-term bets on season outcomes.
- “Lakers to win 2027 NBA Championship” (+800)
- “Kansas City Chiefs to win Super Bowl LXI” (+600)
Futures lock up your capital for months. The tradeoff is higher potential payouts and the ability to bet before the market is efficient. Early-season futures often have the most mispricing.
Live (In-Game) Betting
Bet on events while the game is in progress. Lines update in real time — sometimes every few seconds.
Live betting is the fastest-growing segment of sports betting and the area where AI agents have the biggest structural advantage. A human can’t process a shifting line, model the expected impact of a momentum shift, and execute a trade in under a second. An agent can.
For developers interested in live betting APIs, see the sportsbook API integration guides.
The Vig: How Sportsbooks Make Money
The vig (vigorish), also called juice, is the sportsbook’s built-in commission. It’s how they guarantee profit.
Standard vig on a spread bet:
Team A -7.5 (-110)
Team B +7.5 (-110)
Implied probabilities:
Team A: 110 / (110 + 100) = 52.38%
Team B: 110 / (110 + 100) = 52.38%
Total: 104.76% ← this exceeds 100%
That extra 4.76% is the vig.
To break even at standard -110 odds, you need to win 52.4% of your bets. This is the fundamental barrier. Most recreational bettors win around 48-50% — which means the house slowly grinds their bankroll down.
Reducing the vig you pay is one of the highest-leverage things a beginner can do. Two methods:
- Line shopping — Compare odds across multiple sportsbooks and always take the best price. Getting -105 instead of -110 cuts your break-even win rate from 52.4% to 51.2%.
- Using AI agents — Betting bots automatically compare lines across dozens of sportsbooks in real time and place bets at the best available price.
Bankroll Management
Your bankroll is the total amount of money you’ve set aside for betting. Managing it properly is the difference between surviving a losing streak and going broke.
Flat Betting
Bet the same amount on every wager — typically 1-3% of your bankroll.
Bankroll: $1,000
Bet size: 2% = $20 per bet
After 10 bets (6 wins, 4 losses at -110):
Wins: 6 × $18.18 = +$109.09
Losses: 4 × $20.00 = -$80.00
Net: +$29.09
New bankroll: $1,029.09
Kelly Criterion
A mathematical formula that calculates optimal bet size based on your edge and the odds. Used by sharp bettors and trading algorithms.
Kelly % = (bp - q) / b
Where:
b = decimal odds - 1 (net odds received)
p = probability of winning (your estimate)
q = probability of losing (1 - p)
Example:
Odds: +150 (decimal 2.50, so b = 1.50)
Your estimated probability: 45%
Kelly = (1.50 × 0.45 - 0.55) / 1.50
Kelly = (0.675 - 0.55) / 1.50
Kelly = 0.0833 = 8.33%
Most bettors use fractional Kelly (1/4 to 1/2)
to reduce variance.
Fractional Kelly (betting 25-50% of the full Kelly amount) reduces volatility while still growing your bankroll over time. Most serious bettors and all well-designed betting bots use some variant of Kelly for position sizing.
Sharp vs. Square: What Separates Winners from Losers
Square bettors (recreational) bet on their favorite teams, chase losses, make parlays for entertainment, and don’t track their results.
Sharp bettors (professional) treat betting as a data problem. They:
- Track every bet with detailed records
- Calculate expected value before placing a wager
- Measure their performance against the closing line
- Use multiple sportsbooks to get the best odds
- Never bet more than their edge justifies
Closing Line Value (CLV)
The single best predictor of long-term profitability. The closing line is the final odds before a game starts — it’s the most efficient price because it incorporates the most information.
If you consistently bet at better odds than the closing line, you’re a sharp bettor — even if you hit a rough patch short-term. If the line moves in your direction after you bet, the market is confirming your edge.
Example:
You bet Chiefs -6.5 at -110
The line closes at Chiefs -7.5 at -110
You got a better number (6.5 vs 7.5).
Positive CLV = you're beating the market.
AI agents are built to capture CLV systematically — they monitor line movements across books and execute before the market catches up. See our sharp betting guides for more on CLV-based strategies.
Where to Bet: Regulated vs. Offshore Sportsbooks
Regulated Sportsbooks
Legal, licensed sportsbooks operating in states/countries where sports betting is regulated. Examples: DraftKings, FanDuel, BetMGM, Caesars.
Pros: Legal protection, reliable payouts, responsible gambling tools, no withdrawal issues. Cons: Limited by state availability, aggressive customer limiting (sharp bettors get restricted), and increasingly tight lines.
For developer access, DraftKings and other major books offer APIs — see the agent betting stack for how agents integrate with regulated platforms.
Offshore Sportsbooks
Sportsbooks operating outside US jurisdiction. Higher limits, more markets, less customer restriction — but no legal recourse if something goes wrong.
See our offshore sportsbook guides and offshore sportsbook API integration guides for detailed coverage.
How AI Betting Bots Are Changing Sports Betting
Every edge in this guide — line shopping, CLV, arbitrage, prop market inefficiencies — is something an AI agent does better and faster than a human.
The convergence is here: sportsbooks expose APIs, AI models process vast amounts of data, and autonomous agents connect the two. A modern sports betting bot can:
- Scan odds across 20+ sportsbooks every second and identify the best line
- Calculate expected value on every available market in real time
- Execute bets programmatically through sportsbook APIs before lines move
- Find arbitrage opportunities where guaranteed profit exists across books
- Manage bankroll using Kelly Criterion with automatic position sizing
- Track CLV and evaluate strategy performance without manual spreadsheets
This isn’t theoretical. Open-source bots like OctoBot and purpose-built prediction market agents are live and trading today.
If you’re technical and want to build your own, start with the agent betting stack guide — it covers the four layers (identity, wallet, trading, intelligence) you need to go from zero to a running agent.
If you just want to understand the landscape, browse the betting bot rankings and tool directory.
What’s Next
You now understand how sports betting works, how to read odds, and what separates profitable bettors from the rest. Here’s where to go:
- See how sports betting compares to prediction markets → Sports Betting vs Prediction Markets
- Learn prediction market basics → Prediction Markets 101
- Understand odds as probability → How Prediction Market Odds Work
- Explore automated betting → Betting Bots
- Build your own agent → The Agent Betting Stack
- Find arbitrage opportunities → Sports Betting Arbitrage Bot Guide
- Compare sportsbook APIs → Sportsbook API Guides