Understanding Odds (Decimal, Fractional, American)

To bet successfully on football, you first need to understand how odds work. Odds tell you how likely something is to happen and how much money you’ll win if your bet is successful.

Bookmakers display odds in three main formats:
Decimal Odds
Fractional Odds
American Odds

All three formats represent the same thing — probability and potential payout — just displayed in different ways.

This guide explains each format in simple terms, with examples and conversions.


What Are Betting Odds?

Betting odds show:

  1. The implied chance of something happening
  2. The return you receive if your prediction is correct

For example:

  • Low odds = more likely outcome, smaller returns
  • High odds = less likely outcome, bigger returns

No matter which format you use, the meaning is the same — only the presentation changes.


1. Decimal Odds (Most Common in the UK & Europe)

What decimal odds mean

Decimal odds show the total return for every £1 staked.
The number includes your stake.

Example:

Odds: 1.80
Stake: £10

Return = £10 × 1.80 = £18
Profit = £18 – £10 = £8

Implied probability formula

To convert decimal odds into probability:

Probability (%) = 1 / Decimal Odds × 100

Example:
1 / 1.80 × 100 = 55.5% probability

Why bettors like decimal odds

  • Very easy to calculate
  • Clear total return
  • Used by all betting exchanges

2. Fractional Odds (Traditional UK Format)

What fractional odds mean

Fractional odds show how much you win relative to your stake.

Example:
5/2 means:

  • You win £5 profit for every £2 you stake.

Example bet

Odds: 5/2
Stake: £10
Profit = £25
Return = £35

Implied probability formula

Probability (%) = Denominator / (Numerator + Denominator) × 100

Example with 5/2:
2 / (5 + 2) × 100 = 28.57%

Why fractional odds still exist

  • Used historically by UK bookmakers
  • Still popular in horse racing
  • Many punters grew up with them

3. American Odds (US Format)

American odds use + and numbers.

Positive odds (+150)

Shows how much profit you'd make on a £100 stake.

Example:
+150 → Profit = £150 on £100 stake
Total return = £250

Negative odds (−150)

Shows how much you must stake to win £100 profit.

Example:
−150 → You must stake £150 to win £100


Implied probability formulas

✅ For positive odds (+X):

Probability (%) = 100 / (Odds + 100) × 100

Example: +150
100 / (150 + 100) × 100 = 40%

✅ For negative odds (−X):

Probability (%) = Odds / (Odds + 100) × 100

Example: −150
150 / (150 + 100) × 100 = 60%


Comparing the Odds Formats

All three formats ultimately represent the same thing.

FormatExampleMeaning
Decimal2.50Total return of 2.5× stake
Fractional6/4Profit of £6 for every £4 stake
American+150£150 profit on £100

Converting Between Odds

Decimal → Fractional

Remove 1, convert to a fraction, simplify.

Example:
Decimal 3.50 → Fractional 5/2

Fractional → Decimal

Divide numerator by denominator, then add 1.

Example:
Fractional 5/2 → Decimal 3.50

Decimal ↔ American

  • Decimal under 2.00 = negative American odds
  • Decimal above 2.00 = positive American odds

Example:
Decimal 1.67 → American -150
Decimal 2.50 → American +150


Why Understanding Odds Helps You Bet Smarter

Knowing odds allows you to:

  • Compare bookmakers properly
  • Spot value bets
  • Avoid being misled by long odds
  • Understand implied probability
  • Decide whether a bet is actually worth taking

It’s a core skill for any football bettor.


Safer Gambling Advice

Understanding odds doesn’t guarantee success — it just helps you make better decisions.

Always:

  • Set a clear budget
  • Use deposit limits
  • Keep stakes consistent
  • Avoid chasing losses
  • Don’t gamble when emotional or stressed
  • Take breaks if betting stops being fun

Help and support:

  • BeGambleAware.org
  • GAMSTOP
  • GamCare

Related Glossary Terms


Back to the Main Glossary

Return to Football Betting Glossary