How to calculate odds in US online casinos

If you play at US online casinos or sportsbooks, you’ve likely seen odds displayed in American format. While decimal and fractional odds also appear on some platforms, understanding American odds is essential for calculating your potential winnings.

Whether you’re betting on slots, blackjack, or sports, knowing how to read and calculate odds will help you make better betting decisions.

The three main odds formats

Most US online casinos use American odds, but you may also encounter decimal and fractional odds, especially on international platforms.

• American odds – Shown as +150 or -200 and based on a $100 reference bet.
• Decimal odds – Popular internationally, shown like 2.50, representing the total payout per $1 stake.
• Fractional odds – Rare in the US, shown as 5/2, representing profit relative to stake.

How to calculate winnings from American odds

American odds come in positive and negative values:

• Positive odds (+) – Show how much profit you’d make on a $100 bet.
• Negative odds (−) – Show how much you need to bet to win $100 profit.

Also Read: How to bet on MLB games: Pitcher matchups and stats

Formulas:

Positive:

Profit = Stake × (Odds ÷ 100)
Total Return = Stake + Profit

Negative:

Profit = Stake × (100 ÷ Absolute Value of Odds)  
Total Return = Stake + Profit

Example (positive odds): +150 with $50 stake

• Profit = $50 × (150 ÷ 100) = $75
• Total Return = $75 + $50 = $125

Example (negative odds): −200 with $50 stake

• Profit = $50 × (100 ÷ 200) = $25
• Total Return = $25 + $50 = $75

How to calculate winnings from decimal odds

Decimal odds show the total return, including your stake, per $1 bet.

Formula:

Total Return = Stake × Decimal Odds  
Profit = Total Return − Stake

Example: $50 at odds of 2.50

• Total Return = $50 × 2.50 = $125
• Profit = $125 − $50 = $75

How to calculate winnings from fractional odds

Fractional odds show your profit relative to your stake.

Formula:

Profit = Stake × (Numerator ÷ Denominator)  
Total Return = Stake + Profit

Example: $50 at odds of 5/2

• Profit = $50 × (5 ÷ 2) = $125
• Total Return = $125 + $50 = $175

Why knowing odds is important

Understanding odds in US online casinos allows you to:

• Compare payouts between games or bets
• Spot value bets
• Manage your bankroll effectively
• Avoid costly mistakes

Quick reference table

Odds Type	Example	Stake	Profit	Total Return
American (+)	+150	$50	$75	$125
American (−)	−200	$50	$25	$75
Decimal	2.50	$50	$75	$125
Fractional	5/2	$50	$125	$175

FAQs

Q1: Which odds format is most common in the US?
American odds are the default in most US online casinos and sportsbooks.

Q2: Can I change the odds format in a US casino app?
Yes, most platforms allow you to switch between American, decimal, and fractional odds in the settings.

Q3: Are positive or negative odds better?
Neither is inherently better — positive odds mean bigger payouts but lower probability, while negative odds mean smaller payouts but higher probability.

Q4: Does understanding odds help me win more?
It won’t change the odds of the game, but it helps you make informed bets and manage your money better.

Also Read: How to find value bets in low-profile sports