Betting Odds Converter

The Betting Odds Converter instantly translates any betting price between American (moneyline), Decimal (European) and Fractional (UK) formats, and shows the matching implied probability. It also works out your potential payout for any stake, your break-even win rate, and — uniquely — when you enter both sides of a market it exposes the bookmaker's vig (overround) and reveals the fair, no-vig odds.

What Are Betting Odds?

Betting odds express two things at once: how likely an outcome is, and how much you win if it happens. The three popular formats — American, decimal and fractional — are just different notations for the very same price. Because they all reduce to a single underlying number, you can convert freely between them, and each one also corresponds to an exact implied probability.

Odds Conversion Formulas

Decimal odds are the easiest pivot, because they state the total return per unit staked directly. Every other format is derived from the decimal value d.

Odds Conversion Chart

A quick reference for common betting prices across all three formats and their implied probability:

Understanding American (Moneyline) Odds

American odds are quoted relative to a 100 unit stake. Positive odds (e.g. +150) show how much profit a 100 stake wins, marking an underdog. Negative odds (e.g. -200) show how much you must stake to win 100 in profit, marking a favorite. The closer the number is to ±100, the closer the bet is to a coin flip.

Understanding Decimal (European) Odds

Decimal odds show the total return — stake plus profit — per unit wagered. At 2.50, every 1 unit staked returns 2.50 (a 1.50 profit). Decimal odds are the simplest for calculating payouts: just multiply your stake by the decimal value. They are standard across Europe, Australia, New Zealand and Canada.

Understanding Fractional (UK) Odds

Fractional odds, traditional in the United Kingdom and Ireland, show profit relative to stake. With 5/2, you win 5 units of profit for every 2 units staked. "Evens" (1/1) is a doubling of your money. Odds-on favorites are written with the larger number second, such as 1/2.

Implied Probability and Break-Even Win Rate

Implied probability is the chance of winning baked into the odds, found by dividing 1 by the decimal odds. It doubles as your break-even win rate: at decimal odds of 2.00 (even money), you need to win 50% of the time just to break even; at 1.50 you need 66.7%. If you believe the true chance is higher than the implied probability, you may have found value.

What Is the Vig (Overround)?

Bookmakers do not offer fair odds — they bake in a margin called the vig (also "juice" or "overround"). If you add the implied probabilities of both sides of a two-way market, a fair market would total exactly 100%. In practice it totals more — a classic -110 / -110 market sums to about 104.8%, and that extra 4.8% is the house edge. This calculator's opposing odds field measures that margin for you.

How to Remove the Vig and Find Fair Odds

To strip the vig out, divide each side's implied probability by the combined total, rescaling both sides back to 100%. The result is the fair, no-vig probability and its matching odds — the price you would get in a margin-free market. Comparing fair odds across bookmakers is how sharp bettors hunt for value and the best available line.

How to Use This Calculator

1. Choose the input format: American, decimal, fractional, or implied probability.
2. Enter the odds and (optionally) your stake: for example +150, 2.50, 5/2 or 40. The stake defaults to 100.
3. Optionally add the opposing odds: enter the other side of the market to expose the vig and fair odds.
4. Convert: see every format, implied probability, your payout, break-even rate, and a full step-by-step breakdown.

Frequently Asked Questions

How do I convert American odds to decimal?

For positive American odds, divide by 100 and add 1, so +150 becomes 150 / 100 + 1 = 2.50. For negative American odds, divide 100 by the absolute value and add 1, so -200 becomes 100 / 200 + 1 = 1.50. Decimal odds always state the total return per unit staked.

What is implied probability in betting?

Implied probability is the chance of winning that a set of odds represents. It equals 1 divided by the decimal odds, multiplied by 100. Decimal odds of 2.50 imply a 40% chance. It is also your break-even win rate: you must win at least that often for the bet to be profitable long term.

What is the vig or overround and how do I remove it?

The vig (also called juice or overround) is the bookmaker's built-in margin. When you add the implied probabilities of both sides of a market they total more than 100%; the excess is the vig. To find the fair no-vig odds, divide each side's implied probability by the total and rescale both back to 100%.

What do +150 and -200 mean?

American odds of +150 mean a 100 unit stake wins 150 in profit (an underdog). Odds of -200 mean you must stake 200 to win 100 in profit (a favorite). Positive numbers show profit on a 100 stake; negative numbers show the stake needed to win 100.

Which betting odds format is best?

They all describe the same bet. American (moneyline) odds are standard in the United States, decimal odds are common in Europe, Australia and Canada and are easiest for calculating payouts, and fractional odds are traditional in the United Kingdom and Ireland. Use whichever format you find clearest; this converter shows all of them at once.

How is a betting payout calculated from odds?

Convert the odds to decimal, then total return equals stake multiplied by the decimal odds, and profit equals stake multiplied by the decimal odds minus 1. For example a 100 stake at 2.50 returns 250 in total, of which 150 is profit.

Additional Resources

• Odds - Wikipedia
• Mathematics of Bookmaking - Wikipedia