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Add up both sides' implied probabilities and a two-way market sums past 100%. The excess is the overround — the margin priced into the lines — and from it comes the book's theoretical hold: the share of balanced two-way action it keeps. Two related numbers, two different denominators. This tool shows both, labeled.
Implies 52.38%
Implies 52.38%
Market total
104.76%
Both implied probabilities added — over 100% is the book's cushion
Overround (vig)
4.76%
Market total minus 100%
Theoretical hold
4.55%
Overround ÷ market total — the book's cut of balanced two-way action
Lower hold means a cheaper market. Compare the same game across books, and see what the fair prices would be with the vig removed in the no-vig calculator.
With implied probabilities p_A and p_B from the two prices:
The overround measures how far the prices overshoot 100%. The hold expresses that margin as a fraction of the total handle — what the book keeps when action is balanced, which is why it is the smaller of the two. People say "vig", "juice", and "hold" loosely; when comparing numbers, check which denominator is in play.
Why care? Hold is the price of playing. The same game can cost 4.6% at one book and under 3% at another — and paying less for the same bet is pure arithmetic, no prediction required. To see what the fair lines would be with the margin stripped out, run the pair through the no-vig calculator.
More free tools
These calculators run the exact helpers the Blitzen terminal uses on every board. See them applied to real markets — and how we grade everything against the close.