Bet types, odds formats and the margin built into them
Every sportsbook price can be written three ways, and each way hides the same two numbers: the chance the price implies and the margin the book keeps. This section explains the main bet types, shows how to convert American, decimal and fractional odds, and works through one invented two-outcome market so you can see the margin as a percentage.
Checked by the editorial team on
- 3 min read
- 7 sections
- 1 table
- 3 FAQ
Bet types in one line each
- Moneyline: a bet on who wins.
- Point spread: a handicap added to one side; in hockey, the puck line.
- Over/under (total): a bet on whether the combined score is above or below a set number.
- Parlay: several bets joined into one; every leg must win. A same game parlay (SGP) uses events from one match.
- Prop bet: a bet on a player statistic or a special event.
- Futures: a bet on a tournament or season outcome.
Settlement rules, such as overtime or a postponed game, differ by operator. They are covered under sports and schedules.
Converting odds
American +A gives decimal D = 1 + A/100; American -A gives D = 1 + 100/A. Fractional a/b gives D = 1 + a/b. Implied probability is p = 1/D, and a stake of S pays S × D including the stake.
| American | Decimal | Implied probability |
|---|---|---|
| -150 | 1.67 | 60.0% |
| +120 | 2.20 | 45.5% |
| Sum of the two outcomes | 105.5% |
Takeaway: the two probabilities add up to 105.5%, so the margin in this invented market is 5.5 percentage points. A fair market would add up to 100%.
Where the margin shows
To remove the margin, divide each implied probability by the total. Here 60.0% becomes 56.9% and 45.5% becomes 43.1%. Prices on a real market change by operator and by day, so we publish formulas rather than quotes.
Gambling involves risk, and margin is why long-run results trail the stakes. A converter that does these steps is described on the tools page.
How we checked
- We worked every conversion with the formulas above and rounded to one decimal place.
- We used invented prices, so no operator's odds appear here.
- We will re-check the formulas once a year.
Sources
- Formulas: standard conversion between American, decimal and fractional odds, derived by us and labelled as an example.
What changed
- : first version with one worked example.
Age and help
19+ in Ontario and British Columbia; 18+ in Alberta, Manitoba and Québec. Gambling involves risk. Play responsibly. Need help? See help lines by province. Need a break? Ontario: BetGuard. Alberta: selfexclusion.ca. Not an official site of any operator or regulator.
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FAQ
What is the difference between a moneyline and a point spread?
A moneyline is a bet on who wins. A point spread gives one side a handicap, so the favourite must win by more than the stated margin and the underdog may lose by less. In hockey the spread is called a puck line, usually plus or minus 1.5.
What does vig mean?
Vig, also called juice, is the margin built into the price. When the implied probabilities of all outcomes add up to more than 100%, the excess is the sportsbook's margin.
Can a strategy make a parlay safer?
No. A parlay joins several bets into one, and every leg must win. No staking pattern removes the margin or raises the chance of winning, and we do not suggest one.