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Betting Margin Calculator 2026

Calculate bookmaker margin, overround, and fair odds to find the best value

EV
Developed by Evgeniy Volkov

Enter Market Odds

Margin Rating Guide

Excellent
< 2%
Good
2-4%
Average
4-6%
Poor
6-10%
Very Poor
> 10%

Margin Analysis

Enter odds to see margin analysis

Margin Formulas

How bookmaker margin is calculated

Margin

(1/O₁ + 1/O₂ + ... - 1) × 100

(1/2.10 + 1/3.40 + 1/3.50 - 1) × 100 = 5.18%

Overround

(1/O₁ + 1/O₂ + ...) × 100

(0.476 + 0.294 + 0.286) × 100 = 105.18%

Fair Odds

Odds × (Overround / 100)

2.10 × 1.0518 = 2.21 fair odds

Understanding Betting Margins

📊

What is Margin?

Margin (or vig/juice) is how bookmakers guarantee profit. They offer odds lower than true probability, creating a built-in edge regardless of outcome.

5% margin = book keeps ~5%
📈

What is Overround?

Overround is total implied probability exceeding 100%. A fair market has exactly 100% total probability. Anything above is bookmaker's edge.

105% overround = 5% margin
⚖️

Extracting Fair Odds

Fair odds remove the margin, showing true probability-based prices. Compare offered odds to fair odds to find value bets.

2.10 offered vs 2.21 fair = no value
🔍

Comparing Bookmakers

Lower margin means better value. Betting exchanges (2-3%) beat traditional bookies (5-8%). Always shop for best odds.

2% vs 6% = significant difference

Margin Comparison by Bookmaker Type

Typical margins across different platforms

Bookmaker TypeTypical MarginPayout %Example
Betting Exchange1-3%97-99%Betfair, Betdaq
Sharp Bookmaker2-4%96-98%Pinnacle, SBO
Standard Bookmaker5-8%92-95%Bet365, William Hill
Recreational Book8-15%85-92%Local bookies

Pro Tips

🛒

Shop for Best Odds

Compare margins across bookmakers. A 2% difference in margin significantly impacts long-term profitability.

🔄

Use Betting Exchanges

Exchanges like Betfair offer 2-3% margins vs 5-8% at traditional bookmakers. The savings add up quickly.

📋

Check Market Types

Main markets have lower margins than exotic bets. Stick to 1X2, Over/Under, and handicaps for best value.

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FAQ

Frequently Asked Questions

Bookmaker margin (also called vig, juice, or overround) is the built-in profit percentage that ensures bookmakers make money regardless of outcome. It's the difference between the true probability and the odds offered. A 5% margin means approximately 5% of all stakes go to the bookmaker.
Convert each outcome's odds to implied probability (1/decimal odds), sum them all, subtract 100%. For example: odds 2.10, 3.40, 3.50 give probabilities 47.6% + 29.4% + 28.6% = 105.6%, so margin is 5.6%.
Betting exchanges offer 2-3% margin (excellent). Sharp bookmakers like Pinnacle have 2-4% (good). Standard bookmakers average 5-8% (average). Anything above 10% is considered poor value and should be avoided.
Fair odds are theoretical prices with zero margin, representing true probability. They're calculated by multiplying offered odds by the overround percentage. Comparing fair odds to offered odds helps identify value bets.
Lower margins mean better long-term value. Betting at 2% margin vs 6% margin significantly impacts profitability over time. Professional bettors always seek the lowest margins and best odds.
Exchanges match bettors against each other rather than taking positions. They charge a small commission (2-5%) on winnings only, resulting in much lower effective margins compared to traditional bookmakers.
Yes, margins vary by sport, league, and market type. Main markets (match winner) typically have lower margins than exotic bets (correct score). Popular events often have more competitive margins due to higher liquidity.

About Our Margin Calculator

Our professional margin calculator instantly analyzes any betting market to reveal the bookmaker's edge. Enter odds for all outcomes and see the exact margin, overround, and fair odds with no margin applied.

Understanding margin is crucial for profitable betting. This tool helps you compare bookmaker value, identify overpriced markets, and find the best odds. Used by professional bettors worldwide.

100% free, supports any number of outcomes (2-10), and calculates in real-time. Updated for 2026 with the latest industry-standard formulas.

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Evgeniy Volkov

Evgeny Volkov

Verified Expert
Math & Software Engineer, iGaming Expert

Over 10 years developing software for the gaming industry. Advanced degree in Mathematics. Specializing in probability analysis, RNG algorithms, and mathematical gambling models.

Experience10+
SpecializationiGaming
Status
Active
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