How to Read Betting Odds: American, Decimal & Fractional
Every betting line is a price with a story behind it. Who the book likes, what backing that side costs you, and the cut the house keeps for hanging the line at all. Three formats, five bet types, and one piece of margin math cover the whole board, and after that nothing on it reads as a mystery. Start with the formats, because the price never changes, only the way it’s written.
American, decimal, and fractional odds: the same price, three ways
A price like -150 tells you the same story whether it’s written American, decimal, or fractional. The book changes the display, not the deal.
American odds anchor on $100. A minus number is what you risk to win $100, and a plus number is what you win on a $100 stake. So -150 means you put up $150 to profit $100, and +150 means $100 profits $150. Decimal folds the stake in, so multiply and you get the total return with your money included. Fractional is decimal minus 1, written as a fraction, the classic UK style.
| American | Decimal | Fractional |
|---|---|---|
| -150 | 1.6667 | 2/3 |
| -110 | 1.9091 | ~10/11 |
| +100 | 2.0 | 1/1 (evens) |
| +150 | 2.5 | 3/2 |
| +200 | 3.0 | 2/1 |
American is the default at US books. Decimal runs Europe and Australia, and most books let you flip the display in your account settings. For quick payout math in your head, decimal wins every time, since stake times decimal equals your total return.
The moneyline: pick the winner, mind the price
The moneyline is the whole bet in one price. Who wins, what that costs, no margins and no points.
A negative moneyline marks the favorite. -150 means you risk $150 to win $100, and at 1.6667 decimal that $150 comes back as $250 total. A positive moneyline marks the underdog. +150 means a $100 bet wins $150, decimal 2.5, so $250 back on the win.
The math is two short formulas. On a minus line, profit equals 100 divided by the odds, times your stake. On a plus line, profit equals the odds divided by 100, times your stake. That covers every moneyline you’ll ever see.
Heavy favorites are where new bettors get quietly buried. A -200 favorite sits at 1.5 decimal, so $100 profits just $50. The shorter the price, the more you risk for every dollar you win. Lay -200 four times, lose once, and a single upset erases two winners. Even money is +100, -100, or 2.0 decimal, fifty cents back on every dollar before the book takes its cut. Prices shift by the minute, so pull the live NBA betting odds before you lock anything in.
The point spread: the favorite gives points, the dog gets them
A spread turns a mismatch into something close to a coin flip by spotting the underdog points. The favorite lays them, the dog gets them, and the final margin decides who cashes.
Take a -6.5 favorite. It has to win by 7 or more to cover. The +6.5 underdog covers by winning outright or losing by 6 or fewer. Covering means beating the spread, not the scoreboard. Standard spread pricing is -110 on both sides, 1.9091 decimal, a 52.38% break-even.
Whole numbers can push. If a -6 favorite wins by exactly 6, the margin lands flush on the spread and the bet refunds. That’s why books hang the half-point hook. A -6.5 wipes out the push entirely, so somebody has to lose. Buying that half-point back moves the price, typically toward -120 or -130, because the book charges you for erasing the push risk.
In the NFL, 3, 7, and 10 are the margins that matter, the most common ways a game ends, since so much of the scoring comes in field goals and touchdowns. Buying past a 3 or a 7 costs more than the raw half-point suggests, because you’re crossing the outcomes that happen most. The NFL betting odds board carries today’s spreads, and the pricing frame you’re reading here doesn’t change.
Totals (over/under): betting the scoreboard, not the winner
The total ignores who wins. You’re betting how much scoring happens, the two teams’ combined final score against a figure the book sets. Bet the Over if you expect more, the Under if you expect fewer.
Totals price -110 a side by default, the same 52.38% break-even as a spread. A whole-number total can push. If the line is 8 runs and the game lands on exactly 8, the bet refunds. A half-point total like 8.5 can’t push, because one side always wins.
What sets the line is the scoring environment. Pace, weather, the park or venue, injuries to key scorers or pitchers, and the game script both sides expect. Both sides move together, so steam on the Over drags the whole total up, and the Under you passed on at 8 might be 8.5 an hour later. Current totals across the slate sit on the MLB betting odds board.
Implied probability: what the odds say your bet needs to win
Every line is a probability in disguise. The odds tell you the exact win rate your bet needs just to break even, and reading that is how you know whether it’s worth taking.
Two formulas convert any American line. For a minus number, implied probability is the absolute odds divided by that same figure plus 100. For a plus number, it’s 100 divided by the odds plus 100. Run the common ones and the pattern shows up fast.
| American | Implied win % |
|---|---|
| -200 | 66.67% |
| -150 | 60.0% |
| -110 | 52.38% |
| +100 | 50.0% |
| +150 | 40.0% |
| +200 | 33.33% |
That percentage is your break-even win rate. Take the price only when you make the real chance better than that. A +150 dog is a bet when you think the team is better than a 40% shot, and not a moment before. And -110 implies 52.38%, not 50%. Those extra 2.38 points over a coin flip are the book’s cut, sitting right there in the odds you’re being asked to lay.
The vig: why both sides are -110 and the book still wins
Add both sides’ implied probabilities and they cross 100%. The gap is the house’s guaranteed edge, and it’s the reason a -110/-110 market isn’t the coin flip it looks like.
Two -110 lines each imply 52.38%, which sums to about 104.8%. The 4.8 points over 100 are the overround, 4.76% on the standard market, with the book holding roughly 4.54% of the two-way pool. Break-even sits at 52.38%, so winning half your bets still loses money.
Shopping for cheaper juice is the fix, and it’s the single cheapest edge a bettor can buy. Reduced -105/-105 pricing cuts the overround to 2.44% and drops break-even to 51.22%. Over volume that’s real money. Bet every -110 play at a true 50% win rate and you lose about $4.55 per $100, roughly $45 across ten $100 bets.
Parlays compound all of it. A two-leg parlay at -110 legs pays $264 profit per $100, against $300 at fair odds, an 8.9% house edge that only grows as you add legs. Price a two-leg against its fair payout before you bet into that.
Why the number moves before you can bet it
The price you saw an hour ago is already gone. Lines move on injuries and late scratches, on weather in outdoor sports, and on where the money lands.
Sharp money can push a line against the public. A fast, one-directional move is steam, and it usually means someone with an edge got down first. The opener reflects the book’s first estimate, and the current price reflects everything bet since. Anything you read is a snapshot in time, so confirm it at the book before you bet.
Same math, different lines: run lines, puck lines, and the draw
The run line is the MLB bet most people read backwards. It’s a fixed -1.5 spread, so you back the favorite to win by 2 or more, or take the underdog at +1.5 to lose by one run or win outright. Same idea, one baked-in figure.
Hockey mirrors it. The NHL puck line is a fixed -1.5 spread too, priced with its own moneyline. Basketball and football don’t work that way, since NBA and NFL spreads float to the matchup, anywhere from a pick’em to double digits, instead of sitting on a fixed line.
Soccer adds a third door. It’s a three-way market, home, draw, away, so a tie is its own outcome you can back or fade. Draw no bet refunds your stake if the game ends level, trading a little price for that safety. Futures work differently again, pricing a season-long outcome like a title or an MVP as a single line that drifts all season. Championship futures odds move on every result the sport hands them.
Line shopping: the same bet, a better price
The same game prices differently at different books. One hangs -110, the next -105, and that five-cent gap drops your break-even from 52.38% to 51.22% on the identical bet. Half a point on a spread or total works the same way, and it all compounds across a season.
Line shopping needs accounts at more than one book, which is the whole reason to keep a few open. The sportsbook reviews cover the field and what earns each book its place.
Advertising disclosure: offshore books are our paid lane. Confirm the current terms on the operator’s own site before you deposit.
Four ways new bettors misread a line
- Ignoring the vig. A -110 line isn’t a coin flip. It’s a 52.38% break-even, and pretending otherwise is how a bankroll bleeds out slowly.
- Misreading the sign. Minus is the favorite, risk more to win less. Plus is the underdog, risk less to win more. Flip them and you’ll back the wrong side.
- Never line-shopping. Taking the first price you see leaves value on the table every single bet.
- Chasing parlays. The payout looks huge because the house edge is huge, 8.9% on a two-leg and climbing from there.
Odds move constantly, so treat anything you read as a snapshot and confirm the current price at the book before you bet.
You have to be 21+ where state law requires it. Set the amount you’re okay losing before you place a bet and treat it as the cost of the entertainment. If betting stops being fun, help is free and confidential at 1-800-MY-RESET.
