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No-vig calculator: remove the vig from any two-way market

By George Boyle · Updated 2026-10-18 · The Sport Stack

Devigging is removing the sportsbook’s built-in margin from a price to recover the probability the market actually implies. Raw odds always sum to more than 100% across a market; devigging rescales them back to 100% so you can compare a book’s true opinion against your own, or against a sharper book’s.

No-vig calculator

Enter both sides of a two-way market in American odds to see each side's fair probability and fair price with the vig removed.

Implied 60.0% + 43.5% = 103.5% — an overround of 3.5%.

MethodSide A fairSide B fair
Proportionaleach side divided by the total58.0% (-138)42.0% (+138)
Additivethe margin taken off both sides equally58.3% (-140)41.7% (+140)
Powermore of the margin on the longshot58.4% (-140)41.6% (+140)

Near-even markets agree under every method; they separate on big favourites, where the power method gives the favourite more and the longshot less. Devig each book first, then compare or take the median.

Why raw odds overstate every probability

Convert both sides of a typical -110 / -110 spread to implied probabilities and you get 52.4% + 52.4% = 104.8%. The extra 4.8% is the vigorish — the book’s margin. Taken together, a market’s posted prices overstate the true probabilities of its outcomes, because the book charges you to play.

Using raw implied probabilities in a model or an EV calculation therefore bakes the book’s margin into your math. Devigging removes it: rescale the implied probabilities so they sum to 100%, and what remains is the market’s actual opinion.

The basic method (and when it isn’t enough)

The simplest approach is proportional normalization: divide each side’s implied probability by the sum. For -110/-110 that returns 50%/50%, which matches intuition. For moneylines with a big favorite, proportional devigging is a reasonable start but known to be slightly biased — longshots carry disproportionately more vig (the favorite–longshot bias), and methods like the power or Shin adjustment handle that better.

One rule matters more than the method: devig per book, then aggregate. Averaging raw American prices across books before removing the vig produces a distorted consensus — the correct order is to recover each book’s fair probabilities first, then take the median. Our NFL win-probability consensus is built exactly that way.

A worked example: -150 / +130

Take a moneyline at -150 on the favourite and +130 on the underdog. The raw implied probabilities are 60.0% and 43.5%, which add to 103.5%: an overround of 3.5%, or a hold of 3.4% of every dollar wagered.

Proportional devigging divides each side by that sum, giving 58.0% and 42.0%, fair prices of -138 and +138. The power method puts more of the margin on the longshot and returns 58.4% and 41.6%. Enter any two prices in the calculator above to run the same steps.

What devigged numbers are for

A devigged consensus is the reference point for everything else: whether your model disagrees with the market (an edge claim), whether a stale price at a lagging book is actually value, and whether you beat the closing line. Without devigging first, all three comparisons quietly measure the book’s margin instead of your skill.

Common questions

What does a no-vig calculator do?

It takes the prices on both sides of a market, converts each to an implied probability, and rescales the pair so they add to exactly 100%. What comes out is the fair probability of each side and the fair odds that match it: the price the book would post if it charged no margin.

What is hold in sports betting?

Hold is the share of all money wagered on a market that the book expects to keep if it takes balanced action at its prices. It is 1 minus 1 divided by the sum of the implied probabilities: 4.5% at -110 on both sides, 3.4% on a -150 / +130 moneyline.

What is the no-vig price of -110 / -110?

Even money on both sides. Each side implies 52.4%, the pair sums to 104.8%, and every devig method returns 50% for each — a fair price of +100 — because a symmetric market has no favourite to push the margin toward.

Which devig method should I use?

Proportional is the standard and fine for near-even markets. On big favourites, the power method moves more of the margin onto the longshot, matching the favourite-longshot bias. Whatever the method, devig each book separately before comparing or averaging.

Written by George Boyle, who builds The Sport Stack — the models, the public ledger and these explainers. Corrections and questions: hello@thesportstack.io. Who runs this.

See it in practice