Strategy guide · play money practice
How to read betting odds
Every betting odds number is two facts packed into one: the price of the bet and the probability the market believes. Read them well and you can look at any board — moneylines, spreads, totals — and know instantly what a bet costs, what it pays, and how often it needs to win to break even.
American odds: minus means risk, plus means win
US sportsbooks use American odds, and everything centres on $100:
A minus number (-150) is what you risk to win $100
At -150 you bet $150 to win $100 profit, plus your stake back. Bigger minus numbers mean stronger favourites: -300 is a landslide, -120 is a lean.
A plus number (+150) is what you win on a $100 bet
At +150 you bet $100 to win $150 profit, plus your stake back. Bigger plus numbers mean bigger longshots: +400 pays four times your stake because it wins far less often.
Any stake works — the numbers just scale
You never have to bet $100. At -200, every $2 risked wins $1; at +250, every $1 risked wins $2.50.
That is the payout side. The full moneyline walkthrough — with payout math for real stake sizes — lives in our moneyline guide. The probability side comes next, and it is the part most beginners skip.
Converting odds to probability
Every price implies a break-even win rate, called implied probability. The conversions are simple:
- Minus odds: risk / (risk + 100) = -150 → 150 / 250 = 60%
- Plus odds: 100 / (odds + 100) = +150 → 100 / 250 = 40%
Handy anchors worth memorising:
-400 → 80.0% -110 → 52.4% +150 → 40.0% -250 → 71.4% +100 → 50.0% +300 → 25.0% -200 → 66.7% +120 → 45.5% +400 → 20.0%
Two things follow. First, that percentage is the win rate you need just to break even — a -250 favourite that wins 65% of the time is a losing bet. Second, when you convert both sides of the same game, they sum to more than 100% (two -110 sides imply 104.8%). The overlap is the vig, the book's built-in commission, which we break down fully in the expected value guide.
Reading a full betting board
Real boards stack three markets per game. Here is a single row, annotated:
TEAM SPREAD MONEYLINE TOTAL Ravens -7 (-110) -280 O 44.5 (-110) Browns +7 (-110) +230 U 44.5 (-110)
The spread (-7 / +7) prices the margin
Baltimore must win by more than 7 for spread bettors to cash; Cleveland covers by losing fewer than 7 — or winning outright. The (-110) after each number is the price, not part of the margin.
The moneyline (-280 / +230) prices the winner
Same game, different question. Baltimore is a strong favourite to simply win; +230 pays well if Cleveland pulls the upset.
The total (O/U 44.5) prices combined points
Over bettors need 45 or more combined points; under bettors need 44 or fewer. The half-point (.5) guarantees a decisive result — no pushes.
Notice the two prices never match the two opinions — spread, moneyline and total are independent markets on the same game, each with its own commission. We walk through spread decisions in the point spread guide.
Decimal and fractional odds, in one minute
If you read betting coverage from Europe or the UK, you will meet two other formats. Neither changes the underlying math — they are just different notation:
Decimal odds (2.50): total return per $1
Multiply your stake by the decimal to get everything back, stake included. 2.50 × $100 = $250 total ($150 profit). Implied probability is 1 ÷ decimal: 1/2.50 = 40%. American -150 is decimal 1.67; +150 is decimal 2.50.
Fractional odds (5/1): profit relative to stake
A horse at 5/1 pays $5 profit per $1 staked. Even money is 1/1. It is horse-racing notation, and US sportsbooks almost never use it.
Why the numbers move
Odds are live prices, not printed constants. Lines move for three main reasons: news (a quarterback is ruled out and the line jumps), lopsided betting (the book shifts the number to balance its risk), and sharp money (professional bettors betting early, which books respect). Two practical consequences: the number you see in the morning may be gone by kickoff, and a moving line tells you something — when a +150 dog shortens to +130, the market just became more confident in the upset. If you build your own estimate before looking at the price, movement becomes information instead of noise.
Three reading mistakes to avoid
- 1
Treating the price as a prediction
Odds are shaped by the book's need to balance action as much as by true probability. Public money piles on famous teams, so their prices are often worse than their chances. The line is an opening offer, not a forecast.
- 2
Ignoring the number behind the number
Beginners compare spreads without comparing prices: -7 at -105 and -7 at -125 are different bets. Always read the odds attached to the line, then check whether the implied probability is one you'd accept.
- 3
Reading -110 as 'a little extra'
-110 looks trivial, but it demands 52.4% winners — meaning you must beat the market just to break even. Stacked across hundreds of bets, the vig is exactly why most bettors lose. Shop prices and count the cost.
Practise reading real boards with play money
Reading odds clicks fastest with repetition. EdgeLab is a free simulator: $10,000 in play money, a realistic multi-league board with moneylines, spreads and totals, and an AI coach that grades every bet you place and shows the implied probability you took. Nothing is deposited and nothing is paid out.