How Betting Odds Work

The three odds formats you'll see in Canada

Canadian sportsbooks display odds in three formats, and most apps let you switch between them in settings.

• Decimal (e.g. 2.50): the total return per $1 staked, including your stake. A $10 bet at 2.50 returns $25 ($15 profit + $10 stake). This is the default on most Ontario-facing books and the easiest format for margin maths.
• American (e.g. +150 or -200): positive numbers show profit on a $100 stake (+150 = $150 profit); negative numbers show the stake needed to profit $100 (-200 = risk $200 to win $100). Common on North American books like DraftKings, FanDuel and BetMGM.
• Fractional (e.g. 3/2): profit relative to stake. Less common in Canada but still appears on some markets.

The format changes the display, not the underlying price. 2.50 decimal = +150 American = 3/2 fractional. Convert American to decimal with: for positive odds, (odds/100)+1; for negative odds, (100/|odds|)+1. So +150 → 2.50 and -200 → 1.50.

Turning odds into implied probability

Every price maps to an implied probability — the chance the outcome must have for the bet to break even.

For decimal odds the formula is simply: implied probability = 1 ÷ decimal odds.

• 1.50 → 1/1.50 = 66.7%
• 2.00 → 50.0%
• 2.50 → 40.0%
• 4.00 → 25.0%

This is the single most useful calculation in betting. If you think an NHL underdog has a real 30% chance to win but the price is 4.00 (implied 25%), the book is underpricing that outcome relative to your estimate — that gap is where value lives. If your estimate is below the implied probability, the bet is negative expected value regardless of how it settles.

Why the two sides never add up to 100%

Add the implied probabilities of every outcome in a market and the total exceeds 100%. The overshoot is the bookmaker's margin (also called the overround or vig).

Take a two-way market priced 1.90 / 1.90. Each side implies 1/1.90 = 52.63%. Together that's 105.26%. The extra 5.26% is the margin — the structural edge the book builds into the prices. A fair coin-flip market with no margin would be 2.00 / 2.00 (50% + 50% = 100%).

Margin matters because it's the drag on every bet you place before variance even enters. Lower margin = prices closer to true probability = more of your expected value returned to you over time. This is why margin, not the size of a welcome offer, is the number BETAXIO leads with.

A worked example: comparing two prices

Suppose an NBA moneyline is offered at two books:

• Book A: 1.91
• Book B: 2.00

Your own model says the outcome is a genuine 50% shot. Implied probability at Book A is 1/1.91 = 52.36%; at Book B it's 1/2.00 = 50.00%.

Against your 50% estimate, Book A is charging you 2.36 percentage points of margin on that side, while Book B is priced at fair value. Now the payout on a $100 stake:

• Book A win: $91 profit
• Book B win: $100 profit

Same bet, same risk, +9.9% more profit at Book B on every winning ticket. Repeat that price gap across a season and it compounds heavily. This is exactly what best-price share measures: how often a given book posts the top available number across a sampled set of markets.

What the margin and best-price data shows

From our sampled markets across books available to Canadians, two operators separate from the field on pricing.

Average margin (lower is better): - Pinnacle: 3.12% (221 markets sampled) — the tightest in the set - FanDuel: 4.06% (306 sampled) - DraftKings: 4.21% (898 sampled) - BetMGM: 4.69% (240 sampled) - Caesars Sportsbook: 5.35% (784 sampled) - Unibet: 5.74% (201 sampled) - Betway: 6.09% (191 sampled) - BetRivers: 6.28% (280 sampled) - 888sport: 6.63% (251 sampled) - LeoVegas: 6.86% (167 sampled)

Best-price share (share of sampled markets where the book posted the top price): - DraftKings: 54.5% - Pinnacle: 53.4% - Caesars Sportsbook: 36.7% - FanDuel: 23.5% - BetRivers: 18.9% - BetMGM: 14.6% - Betway: 12.0% - 888sport: 9.2% - Unibet: 8.5% - LeoVegas: 6.0%

Read the two metrics together. Pinnacle carries the lowest average margin, which is why it also lands the top price in over half its sampled markets. DraftKings shows the highest best-price share in this sample at 54.5% on a large 898-market base, with a low 4.21% margin — strong on both dimensions. These are the pricing scores; app quality, market depth and payments are separate ratings and can rank operators differently.

Why prices move: opening vs current line

Odds are not fixed. A book posts an opening line based on its model, then adjusts as money arrives and as information changes — lineup news, an injury, weather for MLB, a lopsided handle on one side. Following the drift between the opening and current line tells you where the market's confidence is shifting.

A line moving from 2.20 to 1.90 means implied probability climbed from 45.5% to 52.6% — the market now rates that outcome roughly 7 points likelier. Bettors who took the earlier price locked in value the current market no longer offers. Live betting compresses this cycle into seconds, with in-play prices recalculated on every meaningful event. You can track these shifts on our market movers feed.

Format, margin and value: putting it together

The workflow for reading any price:

1. Convert the odds to decimal so you can work with them cleanly. 2. Compute implied probability (1 ÷ decimal odds). 3. Compare that against your own estimate — if your probability is higher than the implied figure, there's value. 4. Check the same market at two or three books; the margin gap decides how much of that value survives. 5. Take the best available number, because a 1.91 versus 2.00 gap is real money over volume.

Margin is the reason line shopping works. A book averaging 3.12% is handing back more expected value than one at 6.86% on comparable markets. Serious bettors hold accounts at several books and route each bet to whoever prices it sharpest at that moment.