Hold & Margin Calculator
The margin (or “overround”) is how far the combined implied probabilities sit above 100% — that gap is the sportsbook's built-in edge. The fair odds strip it out so you can see the price you'd need to beat. Two -110 lines carry about a 4.8% margin and a true price of even money.
How to read a book’s margin
Add up the implied probability of every outcome in a market and you'll get a number above 100%. That overage is the hold — the sportsbook's margin baked into the prices. A tighter market (say, 102%) is a better deal than a fat one (108%).
Strip the margin out and you get the fair, no-vig price: each side's honest share of the probability. That fair line is the number any real edge has to beat. If you can find the same game priced better somewhere else, the difference is your value.
Comparing a book's price to the fair line is exactly what our model does on every game — it calculates a true line and only flags a play when the book's price is off by enough to matter.
Frequently asked questions
What is a sportsbook’s hold?
The hold (or margin / overround / vig) is how much the combined implied probabilities of a market exceed 100%. That excess is the sportsbook’s built-in edge — the cut it expects to keep on a balanced book.
How do you calculate the margin?
Convert every side to its implied probability and add them up. A two-sided market at -110 / -110 sums to about 104.8%, so the margin is roughly 4.8%. The bigger the number above 100%, the worse the price.
What are fair (no-vig) odds?
Fair odds are each side’s share of the market once the margin is removed — what the price would be if the book took no cut. Two -110 lines have a fair price of even money (+100) on each side.