Betting odds explained for Quebec: decimal, American and implied probability

Your friend from Toronto sends a screenshot: "Habs +150, easy money." You open Mise-o-jeu+ and see 2,50. Same bet, two languages. Quebec bettors live between both formats, because Loto-Québec shows decimal odds while most North American TV, podcasts and a lot of international books talk in American odds. This guide makes you fluent in both, then shows you the part that actually matters: what the odds say about probability and how much the book is keeping.

How do you read decimal odds?

Decimal odds (cote décimale) tell you your total return per dollar staked, stake included.

Return = stake × decimal odds.

• $20 at 2,50 returns $50: your $20 back plus $30 profit.
• $20 at 1,60 returns $32: your $20 back plus $12 profit.

In French, the decimal point is a comma, so 2,50 on Mise-o-jeu+ is exactly 2.50 on an English-language site. Anything under 2.00 is a favourite (you win less than you stake), anything over 2.00 is an underdog, and 2.00 is a coin flip with no margin.

How do American odds work?

American odds are built around $100, and the sign tells you which way to read them.

• Plus odds (+150) show your profit on a $100 bet. +150 means a $100 bet wins $150 profit. On $20, that is $30 profit.
• Minus odds (-150) show how much you must stake to win $100 profit. -150 means you bet $150 to win $100. On $20, that is $13.33 profit.

The classic "-110" you hear on every NFL broadcast means you bet $110 to win $100, which is 1.91 in decimal. Our NFL betting guide shows how far Mise-o-jeu's NFL lines sit from that benchmark.

How do you convert American odds to decimal?

Two formulas, depending on the sign:

• Plus odds: decimal = 1 + (American / 100). So +150 = 1 + 1.50 = 2.50.
• Minus odds: decimal = 1 + (100 / American, ignoring the sign). So -150 = 1 + 0.667 = 1.67.

And the cheat sheet, including the implied probability we will get to next:

Screenshot it for the next group chat argument.

What is implied probability?

Implied probability (probabilité implicite) is the win chance built into a price. With decimal odds it is one division:

Implied probability = 1 / decimal odds.

At 2,50, that is 1 / 2.50 = 40%. In plain terms: if you bet this price over and over, you need to win more than 40% of the time to come out ahead. That is your break-even rate.

This is the single most useful habit in betting. Instead of asking "will the Habs win?", ask "do the Habs win more than 40% of the time in this spot?" Those are very different questions, and only the second one is about the bet.

How do you find the bookmaker's margin?

Here is where it gets interesting. Take both sides of a market, convert each to implied probability, and add them up.

Example two-way NHL market: Habs 2.40, opponent 1.62.

• Habs: 1 / 2.40 = 41.7%
• Opponent: 1 / 1.62 = 61.7%
• Total: 103.4%

A fair market would add up to exactly 100%. The extra 3.4% is the book's margin (also called the vig, juice or overround; in French, la marge). It is how the book makes money no matter who wins, and it works like the house edge at a casino table.

You can flip it into a payout rate: 100 / 103.4 = about 96.7%. That is roughly what the market pays back across both sides. When Loto-Québec launched Mise-o-jeu+ in 2015, it announced payout rates of 90% on most questions and 92% on some, which is a useful benchmark when you run the same sum on its current prices.

Three-way markets (like a 60-minute hockey result or soccer 1X2) work the same way: add all three. More outcomes usually means a bigger total. Our Mise-o-jeu soccer guide works through a full 1X2 example, draw included.

How do you work out the fair odds?

To strip the margin out and see what the book thinks the real chances are, divide each implied probability by the total.

• Habs: 41.7 / 103.4 = 40.3%, fair odds 2.48
• Opponent: 61.7 / 103.4 = 59.7%, fair odds 1.68

This "no-vig" price is a quick estimate, not gospel, because books do not always spread the margin evenly. But it gives you a solid reference: if another book offers the Habs at 2.55 when the fair price at the first book is about 2.48, that second price is worth a look.

Does the same maths work for puck lines and totals?

Yes, every two-way market works the same way. Two quick examples on a single NHL game:

• Puck line: Habs +1.5 at 1.48 and opponent -1.5 at 2.65. That is 67.6% plus 37.7%, or 105.3%.
• Total: over 6.5 goals at 2.05 and under at 1.82. That is 48.8% plus 54.9%, or 103.7%.

Notice the margins are not identical across markets on the same game. Books often charge a little more on secondary markets than on the main moneyline, and a lot more on props and futures. Running this sum takes thirty seconds and tells you which corner of the menu is cheapest.

Why do odds move before puck drop?

The first number a book posts is the opening line. From there, prices move for two reasons: information and money. A confirmed starting goalie, a late scratch or a flu going around the room is information, and lines react fast. A wave of Saturday-night money on the home team is just money, and books may shade the price against it.

Many serious bettors judge themselves against the closing line, the last price before the game starts. If you regularly get better odds than the close, you are usually reading the market well, win or lose on the night. If you regularly get worse, the market is telling you something.

Common mistakes reading odds

• Mixing up return and profit. A decimal price of 2,50 returns $50 on $20, but your profit is $30.
• Comma versus point. 1,85 and 1.85 are the same number. 185 is not.
• Reading -150 as a loss. It means you stake $150 to win $100, not that you lose $150.
• Treating odds as a prediction. 1.40 means the book makes it about 71%, not a sure thing. Favourites lose all the time.
• Forgetting the free bet catch. A free bet usually pays profit only, so a $10 free bet at 3.00 returns $20, not $30.

Why do different books show different odds?

Books set margins differently, react to news at different speeds and take different money. The gaps are real and they add up.

Same $20 on the same Habs win:

Three dollars on one bet. Across a season, line shopping (comparer les cotes) is the easiest edge anyone has. Our best betting sites in Quebec list is a good place to start comparing, and our Mise-o-jeu+ comparison runs the numbers against international books.

What about fractional odds?

You will mostly see them on UK sites and in horse racing. 3/2 means you win $3 for every $2 staked. To get decimal: divide and add one. 3/2 = 1.5 + 1 = 2.50. Same bet as +150 and 2,50, third outfit. At Quebec's track the odds are pari-mutuel and move until post time; our Hippodrome de Trois-Rivières guide shows how payouts are worked out.

How do parlay odds work?

A parlay (pari combiné) multiplies the decimal odds of each leg.

Three legs at 1.80, 1.90 and 2.10: 1.80 × 1.90 × 2.10 = 7.18. A $10 parlay returns $71.82 if all three hit. Notice that the margins multiply too, which is why parlays look juicy but cost more in the long run. Our same-game parlay guide explains why correlated legs get priced lower than straight multiplication.

Is a bet good value? A two-minute test

Value means the price is higher than the true chance deserves. You can check it with expected value (EV):

EV per $1 = (your probability × profit per $1) - (chance of losing × $1).

Say you honestly believe the Habs win this game 45% of the time, and the price is 2.40 (profit $1.40 per $1).

• 0.45 × 1.40 = 0.63
• 0.55 × 1 = 0.55
• EV = +$0.08 per dollar

On paper that is a good bet. The hard part is the 45%. Most of us overrate our own team, our own read and our last good night. If your estimate is just the book's 40% plus a feeling, the EV is negative.

Quebec odds glossary

Odds explain risk; they do not remove it

Understanding odds makes you a sharper bettor, not an automatic winner. The margin means the average bettor loses over time. Decide your budget before you look at the slip, set a deposit limit at every book, and check our responsible gambling page for breaks and self-exclusion. Jeu: aide et référence is free, confidential and open 24/7 at 1 800 461-0140 (514 527-0140 in the Montreal area).