Sports Betting Odds Explained for Crypto Bettors

If you are new to sports betting, odds can look like random numbers sprinkled across a sportsbook interface. They are not random. Every number encodes three pieces of information: the implied probability of an outcome, the payout you will receive if that outcome occurs, and the sportsbook's margin built into the line. Once you understand how to decode those three elements in any format, you can compare lines across books, identify value, and make sharper decisions with your crypto bankroll.

This guide covers every format you will encounter on crypto sportsbooks, explains the math behind each one, and walks through practical examples you can use immediately.

American Odds

American odds, also called moneyline odds, are the default format at US-facing sportsbooks and are expressed as a positive or negative integer. The sign tells you which side is the favorite and which is the underdog.

Negative odds (example: -110) indicate the favorite. The number represents how much you must bet to win $100 (or 1 unit). At -110, you wager $110 to profit $100. Your total return is $210 ($110 stake returned plus $100 profit).

Positive odds (example: +150) indicate the underdog. The number represents how much you profit on a $100 (or 1 unit) bet. At +150, you wager $100 to profit $150. Your total return is $250.

Payout formulas:

For negative odds: Profit = (Stake / (|Odds| / 100))

For positive odds: Profit = Stake x (Odds / 100)

Quick reference table:

Decimal Odds

Decimal odds are the standard format across Europe, Australia, and most crypto sportsbooks. They represent the total return per unit staked, including your original stake. This makes the math simpler than American odds because there is only one formula.

Total return = Stake x Decimal Odds

Profit = (Stake x Decimal Odds) - Stake

At odds of 2.50, a $100 bet returns $250 total ($150 profit). At odds of 1.91, a $100 bet returns $191 total ($91 profit). Odds of 2.00 represent an even-money bet: you double your stake if you win.

A key insight: any decimal odds figure below 2.00 represents a favorite (you win less than your stake), and anything above 2.00 represents an underdog (you win more than your stake). This makes scanning a market for favorites and underdogs much faster than with American odds.

Decimal odds at a glance:

Fractional Odds

Fractional odds originated in the UK horse racing tradition and are expressed as a ratio such as 3/2 or 10/11. The numerator (left number) is your profit; the denominator (right number) is your stake. Odds of 3/2 mean you profit 3 units for every 2 units staked.

Profit = Stake x (Numerator / Denominator)

At 3/2, a $100 bet profits $150. At 10/11, a $110 bet profits $100 (equivalent to American -110). Even money in fractional odds is expressed as 1/1.

Fractional odds are the least common format on crypto sportsbooks. Platforms like Stake and BC.Game do offer them as a display option, but the vast majority of crypto bettors use decimal or American. If you encounter fractional odds during line shopping, the conversion formula in the later section will let you map them to a more familiar format quickly.

Implied Probability

Implied probability is the conversion of any odds format into a percentage. It represents the win probability that the sportsbook has priced into the line. This is the most important concept for value bettors because comparing your own probability estimate against the implied probability tells you whether a bet has positive or negative expected value.

Conversion formulas:

From decimal odds: Implied Probability = 1 / Decimal Odds

From American odds (positive): Implied Probability = 100 / (Odds + 100)

From American odds (negative): Implied Probability = |Odds| / (|Odds| + 100)

From fractional odds: Implied Probability = Denominator / (Numerator + Denominator)

Examples:

• Decimal 2.50: 1 / 2.50 = 0.40 = 40%
• American +150: 100 / (150 + 100) = 100 / 250 = 40%
• American -110: 110 / (110 + 100) = 110 / 210 = 52.38%
• Fractional 3/2: 2 / (3 + 2) = 2 / 5 = 40%

Notice that +150, 2.50, and 3/2 all produce the same implied probability (40%). They are three representations of the same underlying odds.

Understanding Vig

The vig (short for vigorish), also called juice or overround, is the sportsbook's margin. It is the reason that the implied probabilities for both sides of a market add up to more than 100%. That excess percentage is the house's edge, baked into the price before you place a single bet.

How the overround works:

Consider a standard NFL spread with both sides priced at -110:

• Implied probability of Side A: 110 / 210 = 52.38%
• Implied probability of Side B: 110 / 210 = 52.38%
• Total: 104.76%

The overround is 4.76%. The vig embedded in this line is approximately 4.55% (the overround divided by the total implied probability: 4.76 / 104.76).

Breaking even with vig:

At -110, your break-even win rate is 52.38%. This means you need to correctly predict more than 52 out of every 100 bets just to avoid losing money. Most casual bettors do not clear this threshold.

Calculating vig from any line:

1. Convert both sides to implied probability.
2. Sum the two probabilities.
3. Subtract 100%. The remainder is the overround.
4. Divide the overround by the total to get the vig percentage.

Vig comparison by line:

The best crypto sportsbooks routinely offer -108 or even -105 lines on major markets, compared to the -110 standard at traditional books. Over hundreds of bets, that difference compounds significantly. See the Best Crypto Sportsbooks guide for a current breakdown of which platforms offer the sharpest lines.

How Crypto Sportsbooks Display Odds

Crypto sportsbooks serve a global audience, so most default to decimal odds rather than American. This reflects their European and international user base. However, every major platform allows you to change your preferred display format in account settings.

Platform defaults and format options:

Note that BC.Game also supports Hong Kong (HK) and Malay odds formats, which are common in Asian markets. HK odds work similarly to fractional odds, representing profit per unit staked. Malay odds use both positive and negative values but with different conventions than American odds. For the purposes of this guide, American, decimal, and fractional cover 95% of what you will encounter on the top crypto sports betting sites.

The underlying line never changes when you switch display formats. A line displayed as 1.91 in decimal is mathematically identical to -110 in American and 10/11 in fractional. The display is cosmetic; the value is fixed.

Converting Between Formats

The cleanest method for converting between any two formats is to route through implied probability as an intermediate step. However, direct conversion formulas are faster when you know your starting point.

Decimal to American:

If decimal odds are 2.00 or higher: American = (Decimal - 1) x 100

If decimal odds are below 2.00: American = -100 / (Decimal - 1)

Examples:

• 2.50: (2.50 - 1) x 100 = +150
• 1.91: -100 / (1.91 - 1) = -100 / 0.91 = -109.9 (rounds to -110)

American to Decimal:

If American odds are positive: Decimal = (Odds / 100) + 1

If American odds are negative: Decimal = (100 / |Odds|) + 1

Examples:

• +150: (150 / 100) + 1 = 2.50
• -110: (100 / 110) + 1 = 0.909 + 1 = 1.909 (rounds to 1.91)

Decimal to Fractional:

Convert the decimal to an implied probability, then express the complementary ratio.

A simpler route: Fractional = (Decimal - 1) expressed as a ratio.

• 2.50 - 1 = 1.50 = 3/2
• 1.91 - 1 = 0.909 = approximately 10/11

American to Fractional:

Positive American: Fractional = Odds / 100 (then simplify)

Negative American: Fractional = 100 / |Odds| (then simplify)

Examples:

• +150: 150/100 = 3/2
• -110: 100/110 = 10/11

Conversion reference table:

Practical Examples

Abstract formulas only take you so far. The following scenarios show how to apply everything above to real betting decisions.

Scenario 1: Calculating your payout on a moneyline bet

You want to bet 0.05 BTC on a team listed at +175 (American) or 2.75 (decimal) at Stake.

Decimal calculation: 0.05 x 2.75 = 0.1375 BTC total return. Profit = 0.1375 - 0.05 = 0.0875 BTC.

American calculation: 0.05 x (175/100) = 0.05 x 1.75 = 0.0875 BTC profit.

Both methods confirm an 0.0875 BTC profit on a win.

Scenario 2: Identifying the vig on a spread market

You see an NFL spread priced at Team A -110 / Team B -112 on a crypto book.

• Implied probability of Team A: 110 / 210 = 52.38%
• Implied probability of Team B: 112 / 212 = 52.83%
• Total: 105.21%
• Overround: 5.21%
• Vig: 5.21 / 105.21 = 4.95%

This book is charging slightly more than the standard -110/-110 line. If another book offers the same market at -108/-108, the vig drops to roughly 2.78%, which is significantly more bettor-friendly over volume.

Scenario 3: Checking for value using implied probability

You believe Team C has a 55% chance of winning a game. The sportsbook prices them at -115 (American) or 1.87 (decimal).

Implied probability at -115: 115 / 215 = 53.49%

Your estimate (55%) exceeds the implied probability (53.49%). This is a positive expected value (+EV) spot. The edge is small (1.51 percentage points), but real. Over many similar bets, this edge compounds in your favor.

If the book priced them at -120 instead, the implied probability jumps to 120 / 220 = 54.55%, which is now above your 55% estimate by only 0.45 percentage points. The edge shrinks but is still marginally positive. At -125 (55.56% implied), the bet flips to -EV for your estimate.

Scenario 4: Parlay payout calculation using decimal odds

You want to build a three-leg parlay at Cloudbet. Your selections are priced at 1.91, 2.10, and 1.75 in decimal.

Parlay odds = 1.91 x 2.10 x 1.75 = 7.019

On a 0.01 ETH stake, your total return would be 0.01 x 7.019 = 0.07019 ETH, for a profit of 0.06019 ETH.

Converting the combined parlay odds (7.019) to American: (7.019 - 1) x 100 = +601.9, or roughly +602. The implied probability of this parlay hitting is 1 / 7.019 = 14.25%. For a deeper look at parlay math and how the vig compounds across legs, see the Parlay Math guide.

Scenario 5: Comparing line prices across books

The same game is available at two platforms:

• Book A (crypto-native): Team X at +142 (American) / Team Y at -155
• Book B (traditional): Team X at +135 / Team Y at -155

For Team X, Book A offers +142 (implied probability 41.32%) versus Book B's +135 (42.55%). If you want Team X, Book A gives you 1.23 percentage points more value. Over a $500 bet:

• Book A profit: $500 x 1.42 = $710 return, $210 profit
• Book B profit: $500 x 1.35 = $675 return, $175 profit

That is a $35 difference on a single bet simply from choosing the better line. Line shopping across crypto books is one of the highest-leverage habits you can build. For a full walkthrough of how to fund accounts and place your first bet, see How to Bet on Sports with Bitcoin.

For a broader analysis of expected value in sports betting versus casino games, the Crypto Sports Betting vs Casino: EV Compared guide runs through the long-run math on both sides.