American odds look cryptic the first time you see them. Numbers like +150 and -200, each with a sign and no obvious meaning, decide what a winning wager returns. Once you learn the two formulas behind them, every price on the board becomes readable.

The DraftKings Odds Calculator takes American odds and a stake and translates them into everything else: implied probability, decimal odds, fractional odds, total payout, and profit. It is an educational tool for understanding how odds work, not a prompt to place wagers.

This guide explains each odds format, shows the exact math with four worked examples, and closes with a brief responsible note plus answers to the most common questions.

What American Odds Mean

American odds center on the number 100. A plus sign marks the underdog: +150 means a 100 stake would return 150 in profit if it wins. A minus sign marks the favorite: -200 means you must stake 200 to win 100 in profit.

The sign tells you which side the market favors before any math happens. Plus means the outcome is judged less likely, so the reward is larger. Minus means the outcome is judged more likely, so the reward is smaller relative to the stake.

Odds of +100 and -100 are the even-money boundary. The calculator accepts plus 100 or higher and minus 100 or lower, which covers every standard American price. Anything between those values is not a valid American quote.

How the DraftKings Odds Calculator Works

You enter two values: the American odds exactly as shown, sign included, and the stake in dollars. The calculator validates both, then converts the odds into implied probability, decimal odds, and fractional odds, and finally computes the payout and profit for a winning wager.

The headline result is the implied probability, because it answers the most useful question: how likely does the market think this outcome is? The supporting lines give the decimal and fractional equivalents plus the money figures.

Nothing here predicts the future. The calculator translates prices into probabilities and returns; it does not judge whether a price is good value. Treat every output as information about the market, not advice about what to do.

The Two Inputs: American Odds and Stake

The first field is labeled American odds. Type the number with its sign, for example +150 or -200. Whole numbers are typical, but the calculator accepts decimals too. Values must be plus 100 or higher, or minus 100 or lower.

The second field is labeled Stake. This is the hypothetical amount wagered, in dollars, and it must be greater than zero. The dollar sign sits outside the field as a label; you type only the number.

Choose any stake that helps you learn. Common choices are 100, which makes the plus-odds math transparent, or the amount you are curious about. The calculator scales every money result linearly with the stake.

The formula is:

For plus odds: implied probability = 100 / (odds + 100), decimal odds = 1 + odds / 100. For minus odds: implied probability = |odds| / (|odds| + 100), decimal odds = 1 + 100 / |odds|. Fractional odds reduce the ratio odds:100 for plus prices and 100:|odds| for minus prices. Profit = stake × (decimal − 1). Payout = stake × decimal.

The implied probability formulas convert the price into the break-even win rate: the win percentage you would need for the wager to break even over time. The decimal formulas express the total return per unit staked, which is why profit is the stake times decimal minus one and payout is the stake times decimal.

Implied Probability, Explained

Implied probability is the win rate the odds imply. At +150 the implied probability is 100 / 250 = 40 percent. At -200 it is 200 / 300 = 66.67 percent. These are the break-even rates, not predictions.

This number is the fastest way to compare prices across formats and markets. A 40 percent implied probability means the same thing whether it came from +150, 2.50 decimal, or 3/2 fractional. Learning to read it makes every odds format interchangeable.

Remember that the probabilities on all outcomes of one event add up to more than 100 percent. The extra is the bookmaker margin, the built-in edge that keeps the business profitable. Implied probability describes the market, including its margin.

Decimal Odds, Explained

Decimal odds state the total return per one unit staked, stake included. At 2.50, a 100 stake returns 250 total: the 100 stake back plus 150 profit. At 1.50, a 100 stake returns 150 total: the stake back plus 50 profit.

Decimal is the simplest format for multiplication, which is why the calculator uses it internally for the money math. Payout equals stake times decimal, always. Profit equals stake times decimal minus one, always.

To convert by hand, use the formulas in the formula section: add one to odds divided by 100 for plus prices, or add one to 100 divided by the absolute odds for minus prices. The calculator shows the result to two decimals.

Fractional Odds, Explained

Fractional odds state profit relative to stake as a reduced fraction. At +150 the fraction is 150/100, which reduces to 3/2: three units of profit for every two staked. At -200 it is 100/200, which reduces to 1/2: one unit of profit for every two staked.

This format is traditional in some markets and still appears in coverage and commentary, so recognizing it helps you follow along. The calculator reduces the fraction with the greatest common divisor, so you always see the simplest form.

To read a fraction, divide the first number by the second and multiply by the stake for the profit. At 3/2 with a 100 stake, profit is 1.5 × 100 = 150. Add the stake back for the payout.

Payout Versus Profit

Payout is everything you receive back on a win: your original stake plus the profit. Profit is only the winnings above the stake. Mixing them up is the most common odds mistake, and it roughly doubles the apparent return at short prices.

The calculator shows both on separate lines so the distinction stays clear. At -200 with a 100 stake, the profit is 50 and the payout is 150. Saying you won 150 would be wrong; you won 50 and got your 100 back.

When comparing prices, compare profit for the reward and implied probability for the likelihood. Payout is useful for cash-flow thinking, but profit is the number that measures how much you actually gain.

Worked Example: Plus 150 Underdog

Enter American odds of +150 and a stake of 100. The implied probability is 100 / (150 + 100) = 100 / 250 = 40.00 percent.

Decimal odds are 1 + 150 / 100 = 2.50. Fractional odds are 150/100, which reduces to 3/2. Both describe the same price in different notation.

Profit is 100 × (2.50 − 1) = 150.00 dollars. Payout is 100 × 2.50 = 250.00 dollars. A winning 100 stake returns 250 total, of which 150 is profit.

This is the textbook underdog case: less than even money probability, more than the stake in profit. The 40 percent figure is the break-even win rate the price implies.

Worked Example: Minus 200 Favorite

Enter American odds of -200 and a stake of 100. The implied probability is 200 / (200 + 100) = 200 / 300 = 66.67 percent.

Decimal odds are 1 + 100 / 200 = 1.50. Fractional odds are 100/200, which reduces to 1/2. The short price reflects the favorite status.

Profit is 100 × (1.50 − 1) = 50.00 dollars. Payout is 100 × 1.50 = 150.00 dollars. A winning 100 stake returns 150 total, of which 50 is profit.

Notice the asymmetry: the stake is double the profit. That is the price of backing the likely outcome. The 66.67 percent implied probability is the break-even rate, margin included.

Worked Example: Plus 300 Long Shot

Enter American odds of +300 and a stake of 50. The implied probability is 100 / (300 + 100) = 100 / 400 = 25.00 percent.

Decimal odds are 1 + 300 / 100 = 4.00. Fractional odds are 300/100, which reduces to 3/1. The long price matches the long odds.

Profit is 50 × (4.00 − 1) = 150.00 dollars. Payout is 50 × 4.00 = 200.00 dollars. A winning 50 stake returns 200 total, of which 150 is profit.

Long shots show why the stake matters less than the ratio: the profit is triple the stake here, versus 1.5 times the stake at +150. The calculator makes these comparisons instant.

Worked Example: Minus 150 Favorite

Enter American odds of -150 and a stake of 75. The implied probability is 150 / (150 + 100) = 150 / 250 = 60.00 percent.

Decimal odds are 1 + 100 / 150 = 1.67 when rounded to two decimals. Fractional odds are 100/150, which reduces to 2/3.

Profit is 75 × (1.6667 − 1) = 50.00 dollars. Payout is 75 × 1.6667 = 125.00 dollars. A winning 75 stake returns 125 total, of which 50 is profit.

This example uses an odd stake to show the math scales cleanly. Whether the stake is 75, 100, or any positive number, the probability and the odds formats stay the same and only the money lines move.

Reading Odds on a Sportsbook Screen

On a sportsbook screen, American odds sit next to each outcome with the sign built in. The favorite shows a minus number, the underdog a plus number, and the stake box sits nearby. Enter the two numbers you see into the calculator to decode them.

Watch for odds that move between the time you read them and the time you confirm. The calculator only knows the numbers you type, so if the price changes, run it again with the new number.

Some screens show alternate lines for the same event, each with its own price. Each line is a separate calculation: enter one price and stake at a time rather than mixing numbers from different lines.

Why Odds Move Before a Game

Odds move because money and information move. When more is staked on one side, the bookmaker adjusts the price to balance exposure. When news breaks, such as an injury report, the market reprices the likelihood.

Movement changes the implied probability, which is why a price that looked one way in the morning can look different by evening. The calculator helps you quantify exactly what changed: enter the old price and the new price and compare the probabilities.

None of this reveals which side is value. Movement reflects the market’s opinion and the book’s risk management, not a signal about who will win. Treat moving odds as information about the market, nothing more.

A Brief Responsible Note

This calculator exists to teach how odds work. Understanding implied probability and payouts is useful knowledge even if you never place a wager, and curiosity about the math is a fine reason to use it.

If you do wager, treat it as paid entertainment with money you can afford to lose, never as a way to make money or recover losses. Set limits before you start, and use the limit tools that licensed sportsbooks provide.

If gambling stops being fun, help is available. In the United States you can call or text 988, and the National Council on Problem Gambling helpline is 1-800-522-4700. Stepping back is always an option, and asking for help is a strong move.

Mistakes People Make With Odds Math

The biggest mistake is reading payout as profit, which overstates the win. Always subtract the stake mentally, or better, read the calculator’s separate profit line.

Another is ignoring the sign. Dropping the minus from -200 and treating it as +200 flips a 66.67 percent implied probability into 33.33 percent, a completely different price. Type the sign every time.

A third is assuming implied probability equals true probability. The margin inflates every implied figure, so the market’s numbers always sum past 100 percent. The calculator reports what the price implies, not what will happen.

Frequently Asked Questions

1. What are American odds?

They are the standard odds format in the United States, centered on 100. Plus numbers show the profit on a 100 stake for the underdog, and minus numbers show the stake needed to win 100 on the favorite.

2. Why do odds use plus and minus signs?

The sign identifies the underdog and the favorite at a glance. Plus marks the side judged less likely, with a larger reward. Minus marks the side judged more likely, with a smaller reward relative to stake.

3. What does +150 mean exactly?

It means a 100 stake would profit 150 on a win, for a total payout of 250. The implied probability is 40 percent, the decimal equivalent is 2.50, and the fractional equivalent is 3/2.

4. What does -200 mean exactly?

It means you must stake 200 to profit 100 on a win, for a total payout of 300 on a 200 stake. The implied probability is 66.67 percent, the decimal equivalent is 1.50, and the fractional equivalent is 1/2.

5. How is implied probability different from real probability?

Implied probability is the break-even win rate the price suggests, including the bookmaker margin. Real probability is the actual chance of the outcome, which nobody knows exactly. The calculator reports the implied figure only.

6. Why do the implied probabilities of both sides add up to more than 100 percent?

The excess is the bookmaker margin, sometimes called the vigorish or juice. It is how the book prices in a profit regardless of the outcome. Fair odds with no margin would sum to exactly 100 percent.

7. What is the difference between payout and profit?

Payout is the total returned on a win, including your original stake. Profit is the winnings above the stake. At -200 with a 100 stake, the payout is 150 and the profit is 50.

8. How do I convert American odds to decimal odds?

For plus odds, divide the odds by 100 and add one: +150 becomes 2.50. For minus odds, divide 100 by the absolute odds and add one: -200 becomes 1.50. The calculator does this automatically.

9. How do I convert American odds to fractional odds?

For plus odds, write odds over 100 and reduce: +150 becomes 3/2. For minus odds, write 100 over the absolute odds and reduce: -200 becomes 1/2. The calculator reduces the fraction for you.

10. Why does the calculator reject odds between -100 and +100?

Those values are not valid American odds. The format starts at plus 100 and minus 100, the even-money boundary. Anything between, like +50 or -50, is not a real quote, so the calculator asks for a valid one.

11. Can I enter a stake with cents?

Yes. The stake field accepts decimals, so 25.50 works fine. All money results are shown to two decimals, matching how dollars and cents work.

12. What stake should I enter?

Any positive number that helps you learn. A stake of 100 makes the arithmetic transparent, especially for plus odds. The probability and odds conversions never depend on the stake, only the money lines do.

13. Do sportsbooks use these exact formulas?

Yes, these are the standard definitions behind American, decimal, and fractional odds. Every licensed sportsbook prices from the same math; they differ in the margin they add, not in the conversion formulas.

14. Why do odds change after I see them?

New wagers and new information move the market. Books adjust prices to manage their exposure, so the number on screen is a snapshot. If it changes, run the calculator again with the new price.

15. Is this calculator affiliated with DraftKings?

No. It is an independent educational tool, and the name is used only to describe the American odds format shown by DraftKings and other United States sportsbooks. It is not endorsed by or connected to any sportsbook.