Odds Converter
Convert between American, Decimal, and Fractional odds instantly
What does an odds converter do?
An odds converter translates the same betting price across American, decimal, and fractional formats — and usually to implied probability. Example: +150 → decimal 2.50 → 3/2 → about 40% implied; −150 → about 1.67 → 2/3 → about 60% implied. Formulas: positive American → (A/100)+1; negative → (100/|A|)+1; implied % → (1/decimal)×100.
Use decimal to compare books side by side. Use American for US tickets. Convert before you line-shop so you're comparing the same price — not three different notations.
Convert Betting Odds
Select input format:
Understanding Odds Formats
American Odds
The most common format in the US. Positive odds (+150) show how much you win on a $100 bet. Negative odds (-150) show how much you need to bet to win $100.
Example: +150 means bet $100 to win $150 profit (total return $250)
Example: -150 means bet $150 to win $100 profit (total return $250)
Decimal Odds
Popular in Europe, Australia, and Canada. Decimal odds show your total return for every $1 wagered (including your stake).
Example: 2.50 means bet $100 to receive $250 total (including your $100 stake)
Fractional Odds
Traditional in the UK and Ireland, especially for horse racing. Fractional odds show your profit relative to stake.
Example: 3/2 means bet $2 to win $3 profit (total return $5)
Example: 1/2 means bet $2 to win $1 profit (total return $3)
Why Convert Odds?
Different sportsbooks and regions use different odds formats. Converting between them helps you:
Compare odds across different sportsbooks that use different formats
Understand your potential payout regardless of how odds are displayed
Calculate implied probability to determine if a bet has value
Common Odds Conversions
Here's a quick reference for common betting odds across all three formats. For a broader look at the tools we and others build around these conversions, see our OddsJam alternative breakdown.
| American | Decimal | Fractional | Implied Probability |
|---|---|---|---|
| -500 | 1.20 | 1/5 | 83.33% |
| -400 | 1.25 | 1/4 | 80.00% |
| -300 | 1.33 | 1/3 | 75.00% |
| -200 | 1.50 | 1/2 | 66.67% |
| -150 | 1.67 | 2/3 | 60.00% |
| -110 | 1.91 | 10/11 | 52.38% |
| +100 | 2.00 | 1/1 (Evens) | 50.00% |
| +110 | 2.10 | 11/10 | 47.62% |
| +150 | 2.50 | 3/2 | 40.00% |
| +200 | 3.00 | 2/1 | 33.33% |
| +300 | 4.00 | 3/1 | 25.00% |
| +400 | 5.00 | 4/1 | 20.00% |
| +500 | 6.00 | 5/1 | 16.67% |
| +1000 | 11.00 | 10/1 | 9.09% |
Odds Conversion FAQs
What is a betting odds converter?
A betting odds converter restates one price in every notation — American, decimal and fractional — and shows the implied probability behind it. +150 has an implied probability of 40% and converts to 2.50 decimal or 3/2 fractional; -150 has an implied probability of 60% and converts to 1.67 decimal or 2/3 fractional. The implied probability is the one to work from: it is the only format you can hold against your own estimate of how often the outcome actually happens.
Why do American odds use positive and negative numbers?
Positive American odds (+) indicate an underdog and show profit on a $100 bet. Negative odds (-) indicate a favorite and show how much you must bet to win $100. The larger the negative number, the bigger the favorite; the larger the positive number, the bigger the underdog.
How do I convert American odds to decimal manually?
For positive American odds: Decimal = (American / 100) + 1. For negative American odds: Decimal = (100 / |American|) + 1. Example: +150 = (150/100) + 1 = 2.50 decimal. Example: -150 = (100/150) + 1 = 1.67 decimal.
What does implied probability mean?
Implied probability is the probability of an outcome suggested by the betting odds. It is calculated as: Implied Probability = 1 / Decimal Odds × 100. If you believe the true probability is higher than the implied probability, the bet has positive expected value.
Why don't implied probabilities add up to 100% for both sides?
When you add the implied probabilities of all outcomes in a market, the total exceeds 100%. This excess is called the vig, juice, or margin — it is how sportsbooks make money. For example, -110 on both sides of a spread has a combined implied probability of 104.76%, an overround of 4.76%. That works out to a 4.55% edge for the book: on $220 of balanced action it pays out $210 and keeps $10.
Which odds format is best?
There is no best format — it is a matter of preference and what you are used to. However, many experienced bettors prefer decimal odds because they make it easy to calculate payouts (just multiply stake × odds) and they are widely used internationally. Decimal odds also make it simple to compare value across different bets.
Odds Conversion Formulas
Converting TO Decimal
From American (+):
Decimal = (American / 100) + 1
From American (-):
Decimal = (100 / |American|) + 1
From Fractional (a/b):
Decimal = (a / b) + 1
Converting FROM Decimal
To American (if Decimal ≥ 2):
American = (Decimal - 1) × 100
To American (if Decimal < 2):
American = -100 / (Decimal - 1)
Implied Probability:
Probability = (1 / Decimal) × 100
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What comes after the conversion
An implied probability is where a fair price starts, not where it ends. The vig has to come out of it before the number means anything, and the result has to be measured against what each book is actually posting. The FairLine™ analytics guide walks through that method, and the no-vig calculator does the first step of it on a single market.
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