Step-by-step conversion of American, fractional, and decimal odds for bettors
What is the difference between American odds, fractional odds, and decimal odds? If you've ever had three browser tabs open, one sportsbook showing +150, a UK horse racing site showing 5/2, and a European platform showing 3.50, you already know the frustration. You're staring at what might be the same bet expressed three different ways, or three completely different bets, and you genuinely can't tell. That feeling of standing outside a conversation you weren't invited to is more common than most bettors admit.
Here's the thing: all three numbers are telling you the same story. They're just speaking different dialects. American odds, fractional odds, and decimal odds are three expressions of two core pieces of information: the likelihood of an outcome and what you stand to collect if you're right. Once you learn to translate between them, none of it feels foreign anymore.
At Lay The Points, every daily free pick comes with odds attached. There's a real difference between following a pick blindly and understanding exactly what you're backing, what it implies about the game, and what lands in your pocket if it wins. This article walks through each format step by step, converts between them with real math, and leaves you with a cheat sheet you can actually use.
What is the difference between American, fractional, and decimal odds?
Before any formulas appear, it helps to understand what all three formats are communicating underneath the surface. Every odds format encodes two things: the implied probability of an outcome happening and the return a winning bet produces. The format is just the packaging. The contents are identical.
American odds: the + and − system
American odds, also called moneyline odds, use $100 as their baseline. A negative number like -150 tells you how much you must risk to win $100 in profit. A positive number like +150 tells you how much profit you collect on a $100 stake. The sign itself carries meaning: negative numbers signal the favorite, positive numbers signal the underdog. So when you see -150, you're looking at the team the market expects to win.
Fractional odds: the UK tradition
Fractional odds express profit relative to stake as a ratio. The top number (numerator) is what you win; the bottom number (denominator) is what you wager. So 7/2 means $7 in profit for every $2 risked. This format has deep roots in UK horse racing and traditional bookmakers, and it remains the default display in British and Irish markets. One thing to keep in mind: your original stake comes back to you in addition to the profit, so a winning 7/2 bet on $20 returns both the $70 profit and your $20 back.
Decimal odds: the global standard
Decimal odds are the cleanest format for quick payout math because they already include the returned stake. A line of 2.50 means you receive $2.50 back for every $1.00 wagered, with $1.50 of that being profit and $1.00 being your original stake returned. Most international sportsbooks and European
platforms default to this format, and it's increasingly common on U.S.-facing platforms as an optional display setting.
A quick-reference cheat sheet for all three formats
Before the conversion formulas, a side-by-side table trains your eye to recognize equivalent values across formats. Spend a minute with these numbers and you'll start to feel the pattern without needing to calculate every time.
Common odds equivalents across all three formats
American Fractional Decimal Implied Probability
-200 1/2 1.50 66.7%
-150 2/3 1.67 60.0%
-110 10/11 1.91 52.4%
+100 1/1 2.00 50.0%
+150 3/2 2.50 40.0%
+200 2/1 3.00 33.3%
Why this table matters for bettors
Seeing these values side by side shortcuts the mental translation work. When a UK site shows 3/2 and you're used to reading American odds, one glance tells you you're looking at +150. When a European platform shows 1.91, you recognize it immediately as the standard -110 spread juice. Bookmark this table. It's the fastest odds conversion reference you'll have on hand.
How to convert between American, fractional, and decimal odds
Tables are great when they cover the line you're looking at. But lines don't always match clean round numbers, and that's when knowing the formulas earns its keep. These look a little intimidating written out, but each one is really one or two arithmetic steps. Walk through them once with a real number and they'll stick.
Converting American odds to decimal
For positive odds, divide by 100 and add 1. So +150 becomes (150 / 100) + 1 = 2.50. For negative odds, divide 100 by the absolute value, then add 1. So -150 becomes (100 / 150) + 1 = 1.67. Two versions of the same two-step operation, that's all there is to it. You can use these as a quick payout calculation check any time you switch between platforms.
Converting fractional odds to decimal (and back)
Take the fraction (a/b) and add 1. So 7/2 becomes (7 / 2) + 1 = 4.50. This is the easiest bridge because the arithmetic is straightforward division and addition. Going the other direction, subtract 1 from the decimal to get the fractional profit ratio, then simplify. Decimal is the most useful middle format precisely
because conversion in both directions stays clean, making it a reliable tool whenever you're doing an odds conversion on the fly.
Converting decimal odds back to American odds
Here the formula splits based on whether you're looking at a favorite or an underdog. For lines below 2.00 (favorites): divide -100 by (decimal minus 1). So 1.50 becomes -100 / (1.50 − 1) = -200. For lines at 2.00 or above (underdogs): multiply (decimal minus 1) by 100. So 2.50 becomes (2.50 − 1) × 100 = +150. At exactly 2.00, you land at +100, which is even money.
Implied probability: what the numbers say about your actual chances
Once you can convert between formats, the next layer is the one that separates casual bettors from sharper ones: implied probability. This is the likelihood of an outcome baked into the odds the sportsbook posts. It's not just a math exercise. Understanding it lets you assess whether a line actually offers value.
Calculating implied probability from American odds
For positive odds, divide 100 by (odds + 100). So +150 gives you 100 / 250 = 40%. For negative odds, divide the absolute value by (absolute value + 100). So -150 gives you 150 / 250 = 60%. Take a standard NFL spread: both sides listed at -110. The implied probability on each side is 100 / (110 + 100), which works out to about 52.4%. That's why bettors talk about "beating -110" as their baseline, you need to win more than 52.4% of spread bets at that price just to break even.
NBA moneyline example and the vig
Suppose a 2026 NBA favorite is listed at -200 and the underdog is at +165. The implied probability on the favorite is 200 / 300 = 66.7%. The underdog comes in at 100 / 265 = 37.7%. Add those together and you get 104.4%, not 100%. That overage is the sportsbook's margin, the vig. When your own read on a game puts a team's real win probability meaningfully above the implied number, that gap is where value betting lives. The math isn't the opinion; it just tells you whether the price is fair given your opinion.
What a $100 bet actually returns under each format
All the conversion math lands in one place: your actual payout after a win. Here's how the numbers play out for a few common scenarios, so the formulas connect to something real.
NFL spread: a $100 bet at -110
Profit: $100 × (100 / 110) = $90.91. Total return including your stake: $190.91. This is the standard price on most NFL spread bets, and it's why the breakeven win rate sits at 52.4% rather than 50%. You're not getting dollar-for-dollar on spread bets; the house edge is built in from the start.
NBA moneyline: a $100 bet at +165
Profit: $100 × (165 / 100) = $165.00. Total return: $265.00. Now flip it: if you're betting the favorite at -165, the profit on a $100 bet is $100 × (100 / 165) = $60.61. Total return: $160.61. Same game, same $100 stake, very different outcome depending on which side you're on. That contrast is worth internalizing before you place a bet on a heavy favorite.
Payout comparison for a $100 stake across formats
Odds Format Profit Total Payout
-110 American $90.91 $190.91
10/11 Fractional $90.91 $190.91
1.91 Decimal $91.00 $191.00
The tiny difference in the decimal row is a rounding artifact; 1.91 is a rounded version of the true decimal
equivalent. In practice, these three lines are the same bet. Seeing that confirmed in a table removes any
lingering doubt about whether the format affects your actual payout.
Putting it all together with Lay The Points daily picks
Knowing how to read and convert odds means nothing until you apply it. Real games and real lines are the best classroom, and that's where free daily picks from Lay The Points come in. Every pick posted across NFL, NBA, and other major sports comes with odds attached, giving you a live data point to run through
everything covered here.
Reading a Lay The Points pick end to end
Say you see an NFL pick posted at -115. You now know several things immediately. The implied probability is 115 / (115 + 100) = 53.5%. The profit on a $100 bet is $100 × (100 / 115) = $86.96, for a total return of $186.96. In decimal format, that line converts to (100 / 115) + 1 = 1.87. In fractional terms, it's
roughly 20/23. You haven't placed a bet yet, and you already have a complete picture of what the line is saying.
Spotting value before you place the bet
The real edge comes when your own assessment of a game puts a team's actual win probability above what the implied probability says. That gap, when it exists, is where a bet has positive expected value. The analysis behind each Lay The Points pick gives you a sharp starting point: the team, the line, and the reasoning. Layering the implied probability math on top of that analysis lets you evaluate whether the price is worth taking, not just whether the team looks good. That combination is available at no cost, with no sign-up required, through the daily free picks. It's a ready-made practice ground for applying everything
in this article to real games and real lines.
The same information, three different dialects
The difference between American odds, fractional odds, and decimal odds is not three separate realities. It's the same underlying information expressed in three different conventions shaped by geography and tradition. Once you learn to translate between them, any line on any sportsbook in any country stops being confusing and starts being readable.
To recap: American odds use a $100 baseline, with negatives showing favorites and positives showing underdogs. Fractional odds show profit relative to stake, with your stake returned separately. Decimal odds show the total return per $1 wagered, stake included. The conversion formulas are short. The implied probability math is two steps. The payout calculation is one multiplication.
Bookmark the cheat table from section two. The next time you open a Lay The Points pick and see an odds number next to it, run through the implied probability quickly, calculate the payout on your intended stake, and decide whether the line makes sense given the analysis. That's not advanced handicapping. That's just reading what's already in front of you, and it's a habit worth building from the very first bet.