American Odds Explained: Understanding US Betting Odds & How They Work

Ever stared at a string of numbers with pluses and minuses and wondered what they mean? If you’re new to betting, American odds can look odd at first—especially if you usually see decimal or fractional formats.

Once you know the basics, you’ll be able to read them quickly, spot when a price looks interesting and compare markets with confidence. This guide explains how American odds work, how to convert them, and how they behave in multi-selection bets so you can follow the numbers without stumbling.

Ready to get comfortable with the + and −? Let’s break it down step by step.

What Are American Odds And Where Are They Used?

American odds, also known as moneyline odds, use a plus (+) or minus (−) number to show how a bet is priced. Positive numbers indicate an underdog-style price, while negative numbers point to a favourite-style price; the exact meaning is explained in the next section.

You’ll most often see American odds on US sports—football, basketball and baseball—but many international bookmakers display them too, so they’re worth understanding even if you usually use decimal odds. Learning this format makes it easier to compare the same market across different providers and understand how bookies express price and probability.

If you’re checking several operators, focus on the numbers themselves rather than the platform presenting them; the maths behind the odds is the same wherever you see them.

How Do You Read Positive And Negative American Odds?

American odds use + and − to distinguish between prices. A positive number, such as +200, shows how much profit you would make from a £100 stake; +200 means £100 would return £200 profit, plus the stake. A negative number, such as −150, shows how much you must stake to win £100 profit; −150 means staking £150 to make £100 profit, plus your stake back.

Put simply: plus odds indicate the underdog and show profit on a £100 bet; minus odds indicate the favourite and show the stake required to win £100. This structure makes it quick to see which side a bookmaker favours, once you’re familiar with the signs.

Please bet within your means; understanding odds is useful, but staking sensibly is essential.

How Is Implied Probability Calculated From American Odds?

Implied probability converts a price into a percentage chance, revealing what the market’s price suggests about an outcome. That makes it easier to compare different odds formats on a consistent scale.

For positive American odds (for example, +200) the formula is:
Implied probability (%) = 100 / (odds + 100) × 100
So, +200 gives: 100 / (200 + 100) × 100 = 33.33%

For negative American odds (for example, −150) use the absolute value of the odds:
Implied probability (%) = odds / (odds + 100) × 100
So, −150 gives: 150 / (150 + 100) × 100 = 60%

Roundings can affect the final number shown by bookmakers, so you may see slightly different percentages depending on how many decimal places are used. It is also worth noting that implied probability from a single bookmaker will typically include the bookmaker’s margin, often called the overround, so the summed probabilities for all outcomes in a market will usually exceed 100%.

Viewing prices as percentages helps when you want to assess whether a market looks fairly priced compared with your own view or with alternative formats. Always ensure any betting activity is undertaken responsibly and within legal and regulatory limits.

How To Convert American Odds To Decimal And Fractional

Converting odds lets you compare markets that use different formats without guessing. Here’s a clear way to change American odds into decimal and fractional forms.

To convert to decimal:

• For positive odds (e.g. +200): Decimal = (American odds / 100) + 1 → +200 becomes (200 / 100) + 1 = 3.00
• For negative odds (e.g. −150): Decimal = (100 / absolute value of American odds) + 1 → −150 becomes (100 / 150) + 1 = 1.67

To convert to fractional:

• For positive odds (e.g. +200): Fractional = American odds / 100 → +200 becomes 200/100 = 2/1
• For negative odds (e.g. −150): Fractional = 100 / absolute value of American odds → −150 becomes 100/150 = 2/3

These conversions are handy when you want to read prices in the format you find clearest or when comparing the same market on different sites.

Calculating Payouts And Returns From American Odds

Calculating what you might receive after a winning bet depends on whether the odds are positive or negative and on your stake. For positive odds (for example +250) you divide the odds by 100 and multiply by your stake to find profit: with a £10 bet at +250, (250 / 100) × £10 = £25 profit, so the total return is £35 including the stake.

For negative odds (for example −200) divide 100 by the absolute value of the odds and multiply by your stake: with a £10 stake at −200, (100 / 200) × £10 = £5 profit, so the total return is £15 including the stake.

Different platforms may present potential returns in slightly different ways, but the underlying calculations remain the same. Use these formulas when checking how much you could get back from any given selection.

How Do American Odds Work In Parlays And Accumulators?

Parlays (also called accumulators) combine several selections into a single bet. Every selection must succeed for the parlay to pay out, which increases potential returns and the overall risk.

To form the combined price you convert each leg’s American odds into decimal odds, multiply those decimal figures together and, if needed, convert that combined decimal back into an American-style price. The result shows what the parlay would pay if every leg wins.

Because each added selection increases the chance of at least one losing, parlays offer larger potential returns at higher collective risk. That relationship between reward and risk is the same whether you’re working with American, decimal odds or fractional odds.

How Do American Odds Compare With Decimal Odds For UK Bettors?

Decimal odds are familiar in the UK because they directly show total return per £1 staked, including the original stake. American odds present profit relative to £100 stakes (positive) or the stake needed to secure £100 profit (negative), so they highlight profit and required stake in a different way.

If you prefer quick, at-a-glance totals, decimal odds do that naturally. If you want to see how a bookmaker expresses favourite and underdog differently, American odds make that contrast obvious through the + and − signs. Converting between formats lets you take the clarity of decimal odds while keeping the pricing perspective American odds provide.

Whichever format you use, focus on the numbers and what they imply about probability and payout. If you’d like more comparisons or tools to switch between formats, you can use the calculators available on our site to make those checks effortless.

Final note: knowing how to read and convert American odds gives you more flexibility when comparing markets and spotting value. If you want us to show the same examples with different stakes or markets, we can add those to help you practise.

_{**The information provided in this blog is intended for educational purposes and should not be construed as betting advice or a guarantee of success. Always gamble responsibly.}