MargusKey takeaways - American odds (+150 / -110) are standard in the US. Plus = profit on a 100 stake; minus = stake needed to win 100. - Decimal odds (2.50) are standard in Europe and on exchanges. Multiply stake by the number to get the total return. - Fractional odds (6/4) are traditional in the UK. Profit / stake. - All three formats describe the same price. Once you can convert between them, you can compare any bookmaker, anywhere. - The smaller the payout, the more likely the bookmaker thinks the outcome is. To turn odds into a percentage, see implied probability.
Glossary
- Stake: the amount you bet.
- Profit: what you win on top of your stake.
- Return (payout): stake plus profit.
- Favourite / favorite: the outcome the market thinks is most likely; it pays less.
- Underdog: the less likely outcome; it pays more.
- Even money / evens: you win the same amount you staked. Written as +100, 2.00 or 1/1.
- Moneyline / match result (1X2): a bet on who wins. US sports are usually two-way (no draw); football is usually three-way (home, draw, away).
Why odds formats matter
Every betting price answers two questions: *how much do I get paid?* and *how likely does the bookmaker think this is?* The three formats are just different ways of writing that answer, shaped by history. UK bookmakers grew up with fractional odds, European operators and betting exchanges adopted decimal, and US sportsbooks use American (moneyline) odds.
If you only ever bet with one bookmaker in one country, you can get away with knowing one format. But the moment you want the best price, you need to compare. A UK fan checking an NFL line, or a US bettor looking at a Champions League tie, will see unfamiliar formats. And prediction markets such as Kalshi and Polymarket quote prices in cents, which is a fourth way of saying the same thing. Reading all of them fluently is the foundation of line shopping.
American odds (moneyline)
American odds always revolve around 100.
Positive numbers (underdogs)
A plus sign tells you the profit on a 100 stake.
- +150: bet $100, win $150 profit, get $250 back.
- +300: bet $100, win $300 profit, get $400 back.
Formula: profit = stake × (odds / 100).
Negative numbers (favorites)
A minus sign tells you how much you must stake to win 100 profit.
- -110: bet $110 to win $100, get $210 back.
- -250: bet $250 to win $100, get $350 back.
Formula: profit = stake × (100 / |odds|).
Worked example: NFL moneyline
Say a sportsbook lists Kansas City Chiefs vs Las Vegas Raiders:
| Team | Moneyline |
|---|---|
| Chiefs | -240 |
| Raiders | +200 |
A $50 bet on the Chiefs wins 50 × (100 / 240) = $20.83 profit, returning $70.83. A $50 bet on the Raiders wins 50 × (200 / 100) = $100 profit, returning $150. The bigger negative number marks the favourite; the bigger positive number marks the bigger underdog.
Spreads and totals use the same odds
On a point spread such as Chiefs -6.5 (-110), the -6.5 is the handicap and the -110 is the price. Most US spreads and totals sit at or around -110 on both sides. That is the bookmaker's margin at work, covered in our guide to vig.
Decimal odds
Decimal odds show the total return per 1 unit staked, including your stake.
- 2.50: bet £10, get £25 back (£15 profit).
- 1.40: bet £10, get £14 back (£4 profit).
Formula: return = stake × decimal odds, and profit = stake × (decimal − 1).
Decimal odds are the easiest format to compare at a glance: a higher number always pays more. That is why they are popular on exchanges and comparison sites.
Worked example: Premier League match result
Arsenal v Chelsea, three-way market:
| Outcome | Decimal |
|---|---|
| Arsenal | 1.91 |
| Draw | 3.60 |
| Chelsea | 4.20 |
A €20 bet on the draw returns 20 × 3.60 = €72 (€52 profit). A €20 bet on Arsenal returns €38.20 (€18.20 profit).
Fractional odds
Fractional odds show profit / stake. Read 6/4 as "six to four": you win 6 for every 4 you stake.
- 6/4: bet £4, win £6 profit, get £10 back.
- 1/2 ("two to one on"): bet £2, win £1.
- 10/11: a very common UK price, the equivalent of -110 or about 1.91.
- Evens (1/1): win what you staked.
Formula: profit = stake × (numerator / denominator).
Worked example: Arsenal v Chelsea in fractional
The same match as above, written the UK way:
| Outcome | Fractional |
|---|---|
| Arsenal | 10/11 |
| Draw | 13/5 |
| Chelsea | 16/5 |
A £10 bet on Chelsea at 16/5 wins 10 × 16 ÷ 5 = £32 profit and returns £42. Fractions are easy to say aloud in a betting shop but awkward to compare: is 13/8 better than 7/4? (Yes, 7/4 = 1.75 is longer than 13/8 = 1.625.) Converting to decimal settles it instantly.
Prediction market prices (cents)
Kalshi and Polymarket quote contracts in cents between 0 and 100. A "Yes" contract that pays $1 if the event happens and trades at 40¢ is roughly equivalent to decimal 2.50 or +150, before fees. The price itself reads as a probability: 40¢ ≈ 40%. Our guide to prediction markets vs sportsbooks explains how fees change the comparison.
How to convert between formats
| From | To decimal |
|---|---|
| American positive (+A) | 1 + A/100 |
| American negative (−A) | 1 + 100/A |
| Fractional (N/D) | 1 + N/D |
| Prediction market price (P¢) | 100 / P |
| From decimal (D) | To |
|---|---|
| American, if D ≥ 2.00 | +(D − 1) × 100 |
| American, if D < 2.00 | −100 / (D − 1) |
| Fractional | (D − 1) as a fraction |
Quick reference
| American | Decimal | Fractional | Implied % (approx.) |
|---|---|---|---|
| -300 | 1.33 | 1/3 | 75% |
| -200 | 1.50 | 1/2 | 66.7% |
| -110 | 1.91 | 10/11 | 52.4% |
| +100 | 2.00 | 1/1 (evens) | 50% |
| +150 | 2.50 | 6/4 | 40% |
| +200 | 3.00 | 2/1 | 33.3% |
| +400 | 5.00 | 4/1 | 20% |
| +900 | 10.00 | 9/1 | 10% |
Reading odds on live and in-play markets
Live odds use the same formats, but they move constantly. A Premier League side that was 10/11 before kickoff might drift to 2/1 after conceding, or shorten to 1/5 after scoring twice. In the NFL, a moneyline of -150 can flip to +180 after a turnover. The maths doesn't change: convert to decimal, compare, and check the implied probability. What changes is speed, so know your conversions well enough to do them at a glance.
Common mistakes when reading odds
- Confusing profit with return. Fractional and American odds show profit; decimal shows total return. Mixing them up overstates or understates a payout by exactly your stake.
- Reading -110 as "lose 110". It is the stake required to win 100, not a loss.
- Comparing fractions by eye. Always convert to decimal before deciding which price is better.
- Forgetting the draw. A football "moneyline" usually has three outcomes. A Draw No Bet or double-chance market is a different bet with different prices.
- Ignoring the margin. Odds are not fair probabilities. Each bookmaker builds in a margin, which is why the same match is priced differently across operators.
Expert tips
- Pick decimal as your working format. Even if your bookmaker shows fractional or American, convert to decimal to compare; it makes better prices obvious.
- Think in implied probability. Ask "does this team really win more than 40% of the time?" rather than "is +150 a good price?" See implied probability.
- Small differences add up. -105 versus -115 looks trivial, but over hundreds of bets it is one of the biggest controllable factors in your results. That is the case for line shopping.
- Check the market type. Make sure you are comparing the same bet: full-time result vs to qualify, moneyline including overtime vs regulation only.
- Read our methodology. Margus normalises prices from different operators so they are directly comparable; see how we collect and compare odds.
Compare odds on Margus
Now that you can read any format, put it to work. Margus shows prices from DraftKings, BetRivers, theScore Bet, Kalshi and Polymarket side by side so you can spot the best number in seconds. Browse all odds, check today's NFL odds or football (soccer) odds, and see how sportsbooks stack up against prediction markets.
*Margus is an odds-comparison and research site and does not accept bets. Gambling should be fun, never a way to make money. Set limits and only bet what you can afford to lose. If gambling stops being fun, visit our responsible gaming page for support resources, including BeGambleAware (UK) and 1-800-GAMBLER (US).*
Frequently asked questions
What does +150 mean in betting?
A plus number in American odds shows the profit on a $100 stake. At +150, a $100 bet that wins returns $150 profit plus your $100 stake, $250 in total.
What does -110 mean in betting?
A minus number shows how much you must stake to win $100 profit. At -110 you stake $110 to win $100, so a winning bet returns $210 in total.
What does 5/2 mean in betting?
Fractional odds of 5/2 mean you win £5 profit for every £2 staked. A £10 bet wins £25 profit and returns £35 including your stake.
Which odds format is best?
They all describe the same price. Decimal odds are the easiest for comparing and calculating because they already include your stake, which is why many odds-comparison tools default to them.
What is the difference between odds and probability?
Odds show what a bookmaker pays out; implied probability converts that price into a percentage chance. Bookmaker prices include a margin, so implied probabilities on all outcomes add up to more than 100%.
Can I switch odds formats on Margus?
Margus shows prices from several sportsbooks and prediction markets side by side so you can compare the same market in one place. See the odds pages for current formats.