You're staring at a hockey line that reads -150 on one site and 1.67 on another. Same bet, two completely different-looking numbers. If that's ever made you second-guess your math, you're not alone—Canadian bettors juggle three odds formats daily, often without realizing it. Knowing how to convert betting odds isn't just academic. It's the difference between spotting genuine value and overpaying for a wager you could've gotten cheaper elsewhere.
Here's what this guide delivers: a working understanding of decimal, fractional, and American odds, the exact formulas to flip between them, and how to pull implied probability out of any number you see. We'll use real conversions—the kind you'd run before placing an actual bet. By the end, that -150 versus 1.67 confusion disappears for good. At Betlama, we've watched too many sharp instincts get wasted on bad odds-reading. Let's fix that.
Odds are just a price tag on probability. They tell you two things at once: how likely a bookmaker thinks an outcome is, and how much you'll get paid if you're right. That's it. The confusion only starts because three regions decided to express the same information in three different ways.
Think of it this way. A coin flip has a true probability of 50%. Strip out the bookmaker's cut, and that flip would be priced as 2.00 decimal, 1/1 fractional, or +100 American. Identical bet, three costumes.
Decimal — total return per $1 staked, including your stake back
Fractional — profit relative to your stake, written as a ratio
American — profit on $100, or stake needed to win $100
Once you see them lined up, the panic fades. Here's the same handful of probabilities across all three:
Implied Probability
Decimal
Fractional
American
50%
2.00
1/1
+100
33.3%
3.00
2/1
+200
66.7%
1.50
1/2
-200
20%
5.00
4/1
+400
Decimal, Fractional, and American Side by Side
Notice how decimal odds climb as outcomes get less likely—5.00 means a long shot, 1.50 means a heavy favourite. Fractional tells the same story through a ratio: 4/1 pays four times your stake in profit. American flips its sign depending on which side of even money you're on. A favourite at 66.7% probability shows -200, meaning you risk $200 to win $100. The underdog at 20% shows +400, meaning $100 returns $400 profit. Three languages, one message. Master the translation once and every odds board in Canada—from OLG approved betting sites to anywhere—reads the same.
Why Do Canadian Bookmakers Favour Decimal Odds?
Walk into any Canadian sportsbook app and you'll see decimal odds as the default. There's a practical reason Canadian bookmakers use decimal odds, and it comes down to mental math under pressure.
Decimal odds answer the only question that matters fast: what's my total return? Multiply your stake by the decimal number and you're done. Bet $50 at 2.40? That's $120 back, profit and stake combined. No subtraction, no ratio gymnastics. When you're placing a live bet during a power play and odds shift every few seconds, that simplicity is gold.
Fractional odds force an extra step—you calculate profit, then add your stake separately. American odds make you check a sign before you even start. For a market that grew up alongside European betting platforms and the metric system, decimal was always the natural fit.
Speed — one multiplication gives your full payout instantly
Precision — decimals handle tiny price differences like 1.91 vs 1.95 cleanly
Consistency — favourites and underdogs use the same format, no sign-flipping
Compatibility — matches the European platforms most Canadian operators license from
Honestly, once you've used decimal for a week, going back to fractional feels like doing long division by hand. That said, plenty of Canadian bettors follow UK racing or US sports, so knowing all three keeps you fluent across every market you might touch—including the trusted offshore betting apps that display formats differently.
Reading the Difference Between Decimal and Fractional
The core difference between decimal and fractional odds is what gets counted. Decimal includes your stake in the number; fractional doesn't. Take 6/4 fractional—that's profit of $6 for every $4 risked. Convert it and you get 2.50 decimal, because decimal adds your stake back in. Same bet, different accounting. Fractional thinks in pure profit, decimal thinks in total return. This trips up newcomers constantly: they see 6/4 and 2.50 and assume they're different prices. They're not. One just bakes your stake into the figure and the other keeps it separate.
How to Convert Betting Odds Step by Step
Converting between formats sounds intimidating until you realize it's three short formulas you can run on a phone calculator. Learn these and you'll never need an odds converter app again—though they're handy in a pinch.
Fractional to decimal: Divide the fraction, then add 1. So 5/2 becomes 5 ÷ 2 = 2.5, plus 1 = 3.50 decimal. The "add 1" step folds your stake back into the total. This is the formula to convert fractional odds to decimal, and it never fails.
Decimal to fractional: Subtract 1 from the decimal, then express the result as a fraction. A 3.50 decimal becomes 3.50 − 1 = 2.50, written as 5/2. Subtracting 1 strips your stake out so you're left with pure profit ratio.
Decimal to American (odds of 2.00 or higher): Subtract 1, then multiply by 100. A 2.40 decimal becomes (2.40 − 1) × 100 = +140. The plus sign confirms it's an underdog or even-money bet.
Decimal to American (odds below 2.00): Take −100, then divide by the decimal minus 1. A 1.50 decimal becomes −100 ÷ (1.50 − 1) = −200. The minus sign marks a favourite.
American to decimal (positive odds): Divide the number by 100, then add 1. So +250 becomes 250 ÷ 100 = 2.5, plus 1 = 3.50 decimal.
American to decimal (negative odds): Divide 100 by the absolute number, then add 1. So −200 becomes 100 ÷ 200 = 0.5, plus 1 = 1.50 decimal.
The trick most guides skip: route everything through decimal. It's the universal hub. Going from fractional to American? Convert fractional to decimal first, then decimal to American. Two simple steps beat memorizing six direct conversions. After teaching this to hundreds of beginners, I've found decimal-as-bridge clicks faster than any other method.
Turning Decimal Odds Into Fractional
Let's slow down on one conversion bettors botch most. To convert decimal odds to fractional, subtract 1 and turn the leftover into a fraction in lowest terms. Decimal 1.25? Subtract 1 to get 0.25, which is 1/4. Decimal 4.50? Subtract 1 for 3.50, written as 7/2. The messy ones need reducing—decimal 1.40 gives 0.40, which is 2/5 once simplified. The formula to convert decimal odds to fractional is identical every time: decimal minus one, then fraction it down. Where people stumble is forgetting to reduce. 4/10 and 2/5 are the same price, but bookmakers always show the cleanest version.
What Do Plus and Minus Mean in American Odds?
The single most confusing format for Canadians. So what does plus and minus mean in American odds? The sign tells you whether you're backing a favourite or an underdog, and it sets the $100 reference point.
A minus number is a favourite—it shows how much you must stake to win $100. At -150, you risk $150 to profit $100. A plus number is an underdog—it shows how much profit $100 returns. At +150, a $100 bet wins $150 profit. The bigger the minus, the heavier the favourite; -400 is far more likely than -120. The bigger the plus, the longer the shot. Once you grasp that $100 is the anchor point, learning how to read American odds becomes second nature. The sign is just direction. This matters most on US-style markets like NBA and the elite basketball betting sites Canadians follow.
Working Out Payouts and Implied Probability
Odds aren't only about payouts—they secretly carry the bookmaker's probability estimate baked right in. Crack that open and you start seeing which bets are priced fairly and which are robbing you blind.
Start with the easy half. Here's how to work out a payout from decimal odds: stake × decimal = total return. A $40 bet at 2.75 returns $110. Subtract your stake and your profit is $70. Done. Fractional needs more steps—multiply stake by the fraction for profit, then add stake. American splits by sign, which is exactly why decimal dominates Canadian books.
Decimal payout — $40 × 2.75 = $110 total return
Fractional payout — $40 at 7/4 = $70 profit, plus $40 stake = $110
American payout (+175) — $40 ÷ 100 × 175 = $70 profit, plus stake = $110
All three land on $110 because they're the same price. That's the whole point—format never changes value, only presentation. The same logic applies when you stack legs on parlay betting platforms, where each leg's decimal odds multiply together.
Now the part that actually sharpens your betting: implied probability. Every set of odds tells you the chance the bookmaker assigns. Add up the implied probabilities across all outcomes in a market and you'll get a number above 100%. That overage is the bookmaker's margin—the vig. In our experience reviewing thousands of markets, the gap between true probability and implied probability is where disciplined bettors find their edge. Remember, the margin always favours the house long-term, so realistic expectations matter.
Calculating Implied Probability From Any Format
Here's how to calculate implied probability from odds in seconds. For decimal, divide 1 by the odds, then multiply by 100. A 2.50 decimal gives 1 ÷ 2.50 = 0.40, or 40% implied probability. Clean and instant.
Fractional needs a tweak: divide the denominator by the sum of both numbers. For 3/1, that's 1 ÷ (3 + 1) = 0.25, or 25%. American splits by sign again. Positive odds: 100 ÷ (odds + 100). So +200 gives 100 ÷ 300 = 33.3%. Negative odds: take the absolute value, then divide by (that value + 100). For -150, it's 150 ÷ 250 = 60%. Run these on a few lines and you'll spot when a 40% chance is priced like a 35% one—that's the gap worth hunting.
Where Odds Knowledge Takes You Next
You've got the conversions. Now the real game begins. Reading odds fluently is the foundation, but the bettors who consistently outperform use this skill to hunt for value—comparing the same market across multiple books and pouncing when one prices an outcome softer than the rest. It's a habit that pays off on busy markets like Premier League betting sites where prices swing fast.
That's the natural next step from here:
Line shopping — comparing decimal odds across books to find the best price on identical bets
Removing the vig — stripping out the bookmaker's margin to see true probability
Value betting — backing outcomes where your estimate beats the implied probability
Tracking closing lines — measuring whether you beat the market's final price
Each of these builds directly on the formulas you just learned. We cover value betting and margin removal in dedicated guides at Betlama, since they deserve their own deep dives. And if collecting winnings fast matters to you, our roundup of instant withdrawal betting sites pairs well with sharp odds-reading.
One honest reminder: knowing the math doesn't beat the house edge on its own. It just lets you bet smarter, with clear eyes on what you're actually paying. Keep your stakes within limits you can afford to lose, treat every wager as priced in someone's favour, and let the numbers—not the hype—guide your next move.
