How do I convert American odds to decimal?

For positive American odds: Decimal = (American / 100) + 1. For negative American odds: Decimal = (100 / |American|) + 1. Example: +150 = 2.50 decimal, -150 = 1.67 decimal.

How do I calculate implied probability from odds?

From decimal odds: Implied Probability = 1 / Decimal Odds. From American odds: For negative odds, IP = |odds| / (|odds| + 100). For positive odds, IP = 100 / (odds + 100).

Betting Odds Converter

Convert American, Decimal, and Fractional odds instantly. See implied probability.

Enter odds in any format (we'll convert the rest)

American

Decimal

Fractional

Implied Probability
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No vig adjustment

Break-Even Win Rate

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To profit long-term

💰 Calculate Payout

To Win

$0.00

Total Payout

$0.00

How Betting Odds Work

Betting odds represent the implied probability of an outcome and determine your potential payout. Different regions use different formats:

American odds (+150, -110) — Popular in the US. Positive = underdog, Negative = favorite.
Decimal odds (2.50, 1.91) — Popular in Europe, Australia. Multiply by stake for total payout.
Fractional odds (3/2, 10/11) — Traditional UK format. Numerator = profit, denominator = stake.

American → Decimal

+odds: (odds/100) + 1
-odds: (100/|odds|) + 1

+150 → 2.50
-110 → 1.909

Decimal → American

≥2.0: (dec - 1) × 100
<2.0: -100 / (dec - 1)

2.50 → +150
1.50 → -200

Implied Probability

1 / decimal odds

2.00 → 50%
1.91 → 52.4%

Frequently Asked Questions

What does -110 mean in betting?

-110 means you must bet $110 to win $100 (plus your stake back). This is the standard "vig" or "juice" on point spread bets. The implied probability is 52.38%, meaning you need to win more than 52.38% of your bets to be profitable.

How do I know if odds are good value?

Compare the implied probability to your own estimate. If you believe a team has a 60% chance of winning but the odds imply only 50%, that's a value bet. Use our EV Calculator to quantify the edge.

Why do the probabilities add up to more than 100%?

That's the bookmaker's margin (vig/juice). If Team A is -110 (52.4%) and Team B is -110 (52.4%), that's 104.8% total. The 4.8% overround is the book's profit margin. Lower vig = better for bettors.

Which odds format is best?

Decimal is easiest for calculations — just multiply by stake for total payout. American is useful for quickly seeing favorites (-) vs underdogs (+). Fractional is mainly used for horse racing in the UK.