Betting Odds Explained: Decimal, American and Implied Probability

Last updated: October 2026

Odds look like code the first time you see them: 1.85, -150, +200. They are actually just prices. This page explains the two formats you will meet most often, shows how to turn any price into an implied probability, and explains why odds keep changing. All numbers below are made-up teaching examples, not real prices from any bookmaker.

What odds tell you

Odds tell you two things at once: how much you can win, and how likely the bookmaker thinks the outcome is. A short price (a favourite) pays little because the outcome is likely. A long price (an underdog) pays more because it is less likely. After reading this you can compare any two bets using math instead of gut feel. Pair this page with Bet Types Explained to see where the prices are applied.

Decimal odds

Decimal odds are the easiest format and are common on sites that serve Asia and Europe. The number is the total return per PHP 1 staked, including your stake.

Formula: total return = stake × decimal odds. Profit = total return − stake.

• Stake PHP 100 at 1.80: return PHP 180, profit PHP 80.
• Stake PHP 100 at 2.50: return PHP 250, profit PHP 150.
• Stake PHP 200 at 1.40: return PHP 280, profit PHP 80.

Decimal odds can never be below 1.00. At exactly 1.00 you would get your own money back and nothing more.

American (moneyline) odds

American odds are common in coverage of the NBA and other US sports. They use a plus or minus sign around a base of 100.

• Minus (-150): the favourite. The number is how much you must stake to win PHP 100 profit. Stake PHP 150, win PHP 100 profit, get PHP 250 back.
• Plus (+200): the underdog. The number is the profit on a PHP 100 stake. Stake PHP 100, win PHP 200 profit, get PHP 300 back.

Converting between formats

• +200 equals decimal 3.00 (200 / 100 + 1).
• -150 equals decimal about 1.67 (100 / 150 + 1 = 1.667).
• -200 equals decimal 1.50 (100 / 200 + 1).
• +100 equals decimal 2.00, which is also called even money.

Most sportsbooks let you switch format in settings, so use whichever you read fastest.

Implied probability: the key skill

Implied probability is the chance the price suggests. Convert the odds, and you can ask the real question: do I think the chance is higher or lower than this?

From decimal odds

Implied probability = 1 ÷ decimal odds.

• 1.80: 1 / 1.80 = 0.5556, about 55.6%.
• 2.50: 1 / 2.50 = 0.40, so 40%.
• 4.00: 1 / 4.00 = 0.25, so 25%.

From American odds

• Negative odds: probability = odds (without the sign) ÷ (odds + 100). For -150: 150 / 250 = 0.60, so 60%.
• Positive odds: probability = 100 ÷ (odds + 100). For +200: 100 / 300 = 0.333, so 33.3%.

Worked example: is it value?

A bookmaker offers Team A at 2.50 (implied 40%). You study the game and honestly believe Team A wins about 45% of the time. The price implies less than your estimate, so this could be a value bet. If you believe only 35%, it is not, even if the team is your favourite. Your estimate can be wrong, and a value bet still loses often. Value is a long-run idea, not a promise for tonight.

The bookmaker's margin (the vig)

Add up the implied probabilities of every outcome in a market. A fair market totals 100%. A bookmaker's market totals more, and the extra is the margin.

Example, a two-team game with both sides priced at 1.91 (a common-looking price on spread and totals markets):

• 1 / 1.91 = 52.36% for each side.
• 52.36% + 52.36% = 104.7%.
• The extra 4.7% is the bookmaker's built-in edge.

This is why you can be right about half the time and still lose slowly. At 1.91 you need to win roughly 52.4% of bets just to break even. Shopping for slightly better prices when more than one bookmaker is available is one of the few real edges a casual bettor has.

Why odds move

Odds are not fixed. Prices change because:

1. News. A star player ruled out, a late lineup change, a boxer missing weight. NBA injury reports and PBA import changes can shift a line in minutes.
2. Betting volume. If lots of money lands on one side, the bookmaker shortens that price and lengthens the other to balance its exposure.
3. Sharper information. Professional bettors and models move lines early.
4. Time. Opening lines are often softer than closing lines, which reflect the most information.
5. Live events. In live betting, the score and clock reprice the game every few seconds. See the live betting section in Bet Types.

The price you accept is the price you get. If you place a bet at 1.85 and the line later moves to 1.70, your bet stays at 1.85. Check that your slip does not auto-accept changes you do not want. See How to Bet Online for slip basics.

Quick reference table

FAQ

How to read betting odds in the Philippines?

Check which format the site uses. Decimal: multiply stake by the number. American: minus shows how much to stake to win 100, plus shows the profit on a 100 stake.

What does -110 mean in betting?

You stake 110 to win 100 profit. As decimal that is about 1.91, and the implied probability is 110 / 210 = 52.4%.

Do higher odds mean I will win more?

No. Higher odds mean a lower implied chance. They pay more when they hit but hit less often.

Play responsibly: understanding the math does not remove the risk. Never bet money you need, and read our responsible betting guide to set limits.