Guide · Fundamentals

No-Vig Odds Calculator Guide

Every betting line has the book's margin baked in. Here's exactly how to strip it out and see the market's real, fair probability — with the formulas and worked examples.

What "the vig" actually is

Sportsbooks don't set prices to reflect true 50/50 probability on an even game — they set prices so that both sides of the bet, added together, total more than 100%. That extra percentage is the vig (also called juice or the overround), and it's how the book makes money regardless of who wins. A "pick'em" game priced at -110 / -110 isn't really a 50/50 proposition to the book — implied probability on each side is 52.4%, which sums to 104.8%. The extra 4.8% is margin.

The implied probability formula

Before you can remove the vig, you need to convert American odds into implied probability:

Negative odds (favorite): implied probability = |odds| ÷ (|odds| + 100)
Example: -150 → 150 ÷ 250 = 60.0%

Positive odds (underdog): implied probability = 100 ÷ (odds + 100)
Example: +130 → 100 ÷ 230 = 43.5%

The no-vig (de-vigged) formula

Once you have implied probability for both sides of a two-way market, dividing each side by the sum of both removes the vig proportionally:

fair probability (side A) = implied(A) ÷ (implied(A) + implied(B))

This is the same method used throughout LyDia's own model and the live Value Tools calculator, and it's the standard approach used across the sports betting analytics community — it assumes the book distributes its margin roughly proportionally across both sides, which is a reasonable approximation for liquid two-way MLB markets.

A full worked example

Take a real-looking MLB moneyline: Team A -140, Team B +120.

Step 1 — implied probability: Team A = 140 ÷ 240 = 58.3%. Team B = 100 ÷ 220 = 45.5%.

Step 2 — sum: 58.3% + 45.5% = 103.8%. That's 3.8 percentage points of vig.

Step 3 — de-vig: Team A fair = 58.3 ÷ 103.8 = 56.2%. Team B fair = 45.5 ÷ 103.8 = 43.8%. Notice these now sum to exactly 100%, as a true probability pair should.

That 56.2% is the market's actual, fair-value opinion on Team A — not the 58.3% the raw price suggested. Any model comparison should always be made against this de-vigged number, never the raw implied probability, or you'll systematically understate how much edge you actually need to have.

No-vig for totals and run lines

The same math applies to Over/Under totals (Over vs. Under) and run lines (favorite -1.5 vs. underdog +1.5) — any two-way market works identically. See run line vs. moneyline for how those two markets relate to each other and why a bettor's view on one constrains what they can logically believe about the other.

Why this number matters more than the raw price

No-vig probability is the honest baseline for measuring edge: your model's probability minus the market's fair probability. Comparing your number to the raw (vig-included) price will make almost every bet look better than it really is, since the vig is working against you on both sides. Always de-vig first.

Frequently asked questions

What does "no-vig" mean?

No-vig (also called "fair odds" or "de-vigged") means the sportsbook's built-in profit margin has been mathematically removed from a price, leaving the market's true implied probability for each outcome.

Why don't both sides of a moneyline add up to 100%?

Because the book builds in a margin (the vig, or juice) on both sides of the bet. Adding the implied probabilities of both outcomes on a two-way market will almost always total slightly more than 100% — commonly 102% to 105% for MLB moneylines — and that excess is the book's edge, not a reflection of the true probabilities.

How much vig does a typical MLB moneyline carry?

It varies by book and by how lopsided the game is, but MLB moneylines commonly run 2% to 5% total vig, with lines on heavy favorites (very short prices) tending to carry more vig than close games.

Related reading: What is edge in MLB betting? · How to find value in MLB moneylines · Run line vs. moneyline