No-Vig Odds Calculator

What "vig" actually is

The vig (short for vigorish, also called juice, margin, or overround) is the built-in commission a bookmaker earns regardless of an event’s outcome, by pricing every side of a market slightly worse than its true, fair probability. On a genuinely 50/50 coin-flip event, a zero-margin bookmaker would offer even-money odds (2.00 decimal) on both sides. A real bookmaker instead typically offers something like 1.91 on both sides — still close to even, but each side now implies a probability of about 52.4% instead of the true 50%, and the two sides together imply 104.8%, not 100%. That extra 4.8% is the vig: it’s the bookmaker’s expected long-run take on the market, collected regardless of which side actually wins.

How de-vigging works

The most common method (and the one this calculator uses for two- and three-way markets) is proportional de-vigging: convert every outcome’s odds to implied probability, sum them to find the total overround, then divide each individual outcome’s implied probability by that total sum. The result is a new set of probabilities that sum to exactly 100%, proportionally scaled down from the original margin-inflated figures. Converting those adjusted, "fair" probabilities back into decimal odds gives you an estimate of what the market would look like with the bookmaker’s margin fully removed.

A worked example: two-way odds of 1.91 and 1.91 both imply 52.36% probability, summing to 104.7% (a 4.7% margin). Dividing each side’s 52.36% by 1.047 gives a de-vigged probability of exactly 50% each — converting back to decimal odds of exactly 2.00 on both sides, the fair, no-margin price implied by the market’s own view of the event.

Why de-vigged odds matter for finding value

Serious bettors use de-vigged odds — often averaged across several sharp, high-liquidity bookmakers — as a working estimate of an event’s true probability, then compare that estimate against the actual (margin-included) odds available elsewhere. If a bookmaker’s own price on an outcome is better than what the de-vigged consensus suggests is fair, that’s a signal of possible value — the bookmaker offering that price is, in effect, paying out more than the market’s collective assessment says the outcome is worth. This "compare against a de-vigged baseline" approach is one of the more common, systematic ways bettors try to find an edge, rather than relying purely on their own subjective view of an event.

A caution on the proportional method

Proportional de-vigging, while the most widely used method, is a simplification — it assumes the bookmaker’s margin is spread evenly across every outcome in proportion to that outcome’s own probability, which isn’t always exactly how real bookmakers price markets. Some apply a flatter margin uniformly, others shade specific outcomes more heavily based on which side is attracting more public money. This calculator’s output is a well-established, useful estimate of the fair line, not a mathematically exact reconstruction of a bookmaker’s actual internal pricing model.

Margin varies a lot by market type

Bookmaker margin isn’t a fixed number across every market a sportsbook offers — it typically varies quite a bit depending on the sport, the specific market, and how much betting volume and sharp attention that market attracts. Major markets on popular events (like the moneyline on a top football league match) tend to carry tighter, more competitive margins, often in the low single digits, since heavy betting volume and competition between sportsbooks pressure the price toward fair value. Niche markets, obscure leagues, and exotic bet types (like specific player props or long-term futures) typically carry noticeably wider margins, since less betting volume and attention give the bookmaker more room to price in a larger cut without it being immediately obvious or competed away.

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