How to Read Betting Odds – Decimal, Fractional, American

Betting odds tell you two things: how much a winning bet pays and how likely the bookmaker thinks the outcome is. Decimal odds of 2.50 return 2.50 per 1 staked (stake included); fractional 3/2 wins 3 per 2 staked; American +150 wins 150 on a 100 stake. All three are the same price, and all three imply a 40% chance.

This guide shows how to read each format, how to convert between them, what the plus and minus signs mean, and how to read the line itself (handicaps and totals). Examples use real Pinnacle prices.

Definition. Betting odds are the price a bookmaker offers on an outcome. They set the payout and, through implied probability (1 ÷ decimal odds), show the chance the price assumes, including the bookmaker's margin.

How do decimal odds work?

Decimal odds show the total return for every 1 unit staked, stake included. They are the default in Europe and at Pinnacle.

• Total return = stake × odds
• Net win = stake × (odds − 1)

A €10 bet at 2.50 returns €25: €15 won plus your €10 back. At 2.00 (evens) the net win equals the stake. Below 2.00 the net win is smaller than the stake (the outcome is the favourite, "odds-on"); above 2.00 it is larger ("odds-against"). Odds-on vs odds-against covers what that changes for break-even rates and variance.

Decimal odds are the easiest format for value betting, because the fair-price and expected value formulas use them directly.

How do fractional odds work?

Fractional odds show net winnings relative to stake, without the stake. Read 5/2 as "win 5 for every 2 staked". They are traditional in the UK and Ireland, especially in horse racing.

• Net win = stake × numerator ÷ denominator
• Total return = net win + stake

£20 at 5/2 wins £50 and returns £70. 1/1 is evens (2.00 decimal). 1/2 is odds-on: £10 wins £5.

Decimal = (numerator ÷ denominator) + 1. So 5/2 = 3.50 and 1/2 = 1.50.

What do + and − mean in American odds?

American (moneyline) odds use a 100 reference.

• Plus (+) is the net win on a 100 stake. +150 wins 150 on 100. It marks the underdog.
• Minus (−) is the stake needed to win 100. −110 means bet 110 to win 100. It marks the favourite.

Stakes scale: $30 at −150 wins $20; $10 at +200 wins $20.

To decimal: for plus odds, (odds ÷ 100) + 1, so +150 = 2.50. For minus odds, (100 ÷ |odds|) + 1, so −110 ≈ 1.909.

The −110 on both sides of a US spread or total is the standard example of the bookmaker's margin: each side implies 52.4%, together 104.8%. See overround, vig and margin explained.

Odds conversion table

For any other price, use the odds converter. Some Asian bookmakers also show Hong Kong odds (decimal minus 1) and Malay or Indonesian odds; they are the same price in another notation.

How do you turn odds into a probability?

Divide 1 by the decimal odds. 2.50 → 1 ÷ 2.50 = 40%. For American minus odds: |odds| ÷ (|odds| + 100), so −150 → 150 ÷ 250 = 60%. For plus odds: 100 ÷ (odds + 100), so +150 → 40%. The full method, including how to go from implied to fair probability, is in implied probability explained.

That number still contains the bookmaker's margin. Add the implied probabilities of every outcome in a market and you get more than 100%; the excess is the margin. Removing it gives the fair price, which is what you compare offers against. The devig calculator does it for a whole market, and the margin calculator shows the overround.

How do you read the line: handicaps and totals?

The odds are the price; the line is what you are betting on.

• Handicap (spread). "Team −1.5 at 2.84" means the team must win by 2 or more. "+1.5" means the side can lose by 1 and still win the bet.
• Totals (over/under). "Over 2.5 goals at 1.90" wins with 3 goals or more. Whole lines (3.0) refund the stake on exactly 3; quarter lines (2.25) split the stake across the two neighbouring lines.
• Three-way vs two-way. A football 1X2 has three outcomes (home, draw, away). A tennis or basketball moneyline has two. Never compare a three-way price with a two-way price for the same team.

Real example: one Pinnacle price in every format

From Pinnacle Terminal screenshots taken on 28 October 2026 at 09:36–09:37 (Madrid time, CET).

ITF Women Taby, Bernstein −1.5 games. The price fell from 3.52 to 2.88.

• 3.52 decimal = +252 American ≈ 5/2 fractional (exactly 63/25). Implied probability 28.4%.
• 2.88 decimal = +188 American. Implied probability 34.7%.
• A €10 bet at 3.52 would return €35.20; at 2.88, €28.80.
• Fair price after removing the margin (power method): 3.138.

ITF Men Norman, Daryabeigi −1.5 games. Flagged as a Big move from 3.38 to 2.84, later 2.24.

• 2.84 = +184; 2.24 = +124. Implied probability 35.2% → 44.6%.

Read this way, the odds stop being just payouts. A shorter price is a higher implied probability; when Pinnacle's price falls, the market has moved its estimate. That is the basis of reading odds movement and of dropping odds.

Common mistakes when reading odds

• Forgetting the stake in fractional odds. 5/2 returns 3.5 times the stake, not 2.5.
• Reading −110 as a loss. It is a favourite-style price: 110 to win 100, total return 210.
• Treating implied probability as the true chance. It includes the margin; devig first.
• Comparing different lines. A price on −1.5 and a price on −1 are different bets.
• Comparing formats by eye. Convert to decimal before comparing two bookmakers.

How Pinnacle Terminal handles this

Pinnacle Terminal shows Pinnacle's prices in decimal, with the fair price (NVP) next to each line, calculated by power devig by default, with multiplicative, additive and Shin also available plus a worst-case figure. Every pre-match move is graded 0–10 and labelled (Big move, Sharp drop, Limit-backed, Downtrend, Rebound, Standard), so you instantly see which price changes matter; live in-play drops are shown as they happen and filtered, without a grade. The terminal does not accept bets and is not affiliated with Pinnacle. See the Pinnacle dropping odds page.

FAQ

What does +150 mean in betting?

A 100 stake wins 150 and returns 250 in total. It equals decimal 2.50 and fractional 3/2, with an implied probability of 40%.

What does −110 mean?

You stake 110 to win 100. It equals decimal 1.909 and implies 52.4%.

Which odds format is best?

Decimal, for most purposes: one multiplication gives the return, and fair-price and EV formulas use it directly. The price is the same in every format.

Do lower odds mean a more likely outcome?

Yes. Lower decimal odds mean a higher implied probability. They do not mean the outcome will happen, and the implied figure includes the bookmaker's margin.

How do I calculate my payout?

Decimal: stake × odds. Fractional: stake × fraction + stake. American plus: stake × odds ÷ 100 + stake; minus: stake × 100 ÷ |odds| + stake.

Try it

See Pinnacle's prices and fair odds live, with every pre-match move graded 0–10 and live in-play drops filtered: start the Pinnacle Terminal 7-day free trial. Nothing is charged before day 8.

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