Free Tools

Betting Calculators

Size every bet, evaluate every price, convert every format. The same maths sharps run — built into clean, mobile-friendly tools.

Vig / Juice Calculator

Calculate the bookmaker's built-in margin (vig). Lower vig means better value. Compare books to find the fairest odds.

Excellent (<3%) — Pinnacle, Betfair Exchange

Good (3-5%) — DraftKings, FanDuel, Bet365

Average (5-8%) — Most recreational sportsbooks

High (8%+) — Avoid for serious betting

What is Vig (Juice)?

The vig (short for vigorish, also called "juice") is the bookmaker's built-in profit margin. It's the reason the implied probabilities of both sides of a bet add up to more than 100%. The difference between 100% and the total is the vig — it's the price you pay for placing the bet.

Why Vig Matters

Lower vig means you're getting closer to the true fair odds. Over hundreds of bets, a 2% difference in vig compounds significantly. If you consistently bet at books with 3% vig instead of 6%, you're effectively doubling your profit margin. This is why sharp bettors are obsessive about finding the best lines.

Fair Odds Explained

The "Fair Odds" shown above are what the odds would be if the bookmaker took zero margin. They represent the true market probability without any vig built in. Compare these to the actual offered odds to see exactly how much you're paying in vig on each side of the market.

Diary of a Pro Gambler

Sports betting community with 10+ years of profitable results across UFC and Football. Live betting audio, daily tips, and data-driven tools.

18+ only. Gambling can be harmful. Content on this site is opinion and entertainment — not financial advice. Please gamble responsibly. Free, confidential help is available 24/7 on the National Gambling Helpline: 0808 8020 133.

© 2026 Diary of a Pro Gambler. All rights reserved.