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Betting Vig Calculator

Calculate the bookmaker's margin (vigorish) and find the true odds with zero margin.

2 outcome(s)
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2

How It Works

💰 What is Vigorish?

Vigorish (vig) or juice is the bookmaker's commission built into the odds. It's the difference between the true probability of outcomes and the odds offered by the bookmaker.

Example: In a fair coin toss, both heads and tails should have 2.00 odds (50% probability each). But a bookmaker might offer 1.91 for both, building in a 5% margin.

🧮 Calculation Formula

Implied Probability = (1 / Odds) × 100
Total Implied Probability = Sum of all implied probabilities
Vigorish = Total Implied Probability - 100
True Odds = 100 / (Implied Prob / Total Implied Prob × 100)

📊 Vig Benchmarks

Excellent< 3% (Sharp bookmakers, exchanges)
Good3-5% (Competitive markets)
Average5-8% (Standard bookmakers)
Poor> 8% (Recreational books, niche markets)

💡 Using This Calculator

  • •Compare bookmakers: Check which bookmaker offers the best margins on a market
  • •Find value bets: If a bookmaker's odds are higher than the true odds, it may be value
  • •Identify arbitrage: Low vig markets make finding arbitrage opportunities easier
  • •Understand value: The true odds show what fair odds would be without bookmaker margin

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Find the Best Odds Automatically

Our Oddsmatcher compares margins across 20+ bookmakers to find you the best value every time.

A vig calculator (also called a juice or overround calculator) shows how much a bookmaker builds into a set of odds as their margin. It converts the offered odds into implied probabilities, sums them, and expresses the excess above 100% as the bookmaker margin.

Enter the odds for each outcome in a market. The calculator shows the overround percentage, the fair odds with zero margin, and how much value you lose on each bet at the current prices.

How to Use the Vig Calculator

  1. 1
    Select number of outcomes — 2-way for head-to-head markets, 3-way for football 1X2.
  2. 2
    Enter the decimal odds for each outcome — from the bookmaker you are evaluating.
  3. 3
    Read the overround and fair odds — the calculator shows the bookmaker margin and what the true odds would be at zero margin.

The Vig Formula: A Worked Example

Formula

Overround (%) = (Sum of 1/odds for all outcomes − 1) × 100

Example: 2-way market

Outcome A @ 1.90 | Outcome B @ 1.90

Sum = 1/1.90 + 1/1.90 = 0.526 + 0.526 = 1.053

Overround = (1.053 − 1) × 100 = 5.3% vig

Fair odds at 50/50 would be 2.0 each. You receive 1.90: the 5.3% overround is the bookmaker margin.

Fair odds formula

Fair odds = Actual odds × Sum of implied probabilities

1.90 × 1.053 = 2.0. The fair price is 2.0; you are paying 5.3% vig for the privilege of betting.

Why Vig Matters for Matched Bettors

High vig means larger qualifying losses on matched bets. When backing at a bookmaker with 8% overround versus one with 4%, you need better lay odds to break even on the qualifying bet.

Exchanges charge commission rather than building vig into odds. This is why exchange prices are almost always better than bookmaker prices for the same market, and why the exchange commission calculator is a companion to this one.

Common Mistakes When Analysing Vig

  • ✕
    Comparing markets of different sizes. A 2-way market at 5% overround is worse than a 3-way market at 6% overround per outcome. Normalise by dividing total overround by number of outcomes.
  • ✕
    Ignoring vig when assessing qualifying bets. A qualifying bet at 3.50 with 8% bookmaker vig requires better lay odds than one at 3.50 with 4% vig. Always check the overround before confirming a bet.
  • ✕
    Treating exchange odds as vig-free. Exchanges charge commission, which is effectively vig on winning bets. Use the exchange commission calculator to compare true net odds.

Frequently Asked Questions

What is vig in sports betting?

Vig (vigorish), also called juice or overround, is the bookmaker margin built into odds. When the implied probabilities across all outcomes in a market sum above 100%, the excess is the vig. A standard football market has 5–12% overround.

What is overround in betting?

Overround is the same concept as vig expressed differently. If implied probabilities across all outcomes sum to 110%, the overround is 10%. A fair book would sum to exactly 100%.

How does vig affect my qualifying loss?

Higher vig means the bookmaker odds are further below fair value, which requires a larger lay stake relative to the back stake to cover all outcomes. This increases the spread between back and lay, raising your qualifying loss.

What is a typical bookmaker overround?

Mainstream football 1X2 markets typically carry 5–8% overround at major bookmakers. Horse racing markets can reach 15–20%. Betting exchanges price at near-zero overround and charge commission on winnings instead.