Calculator
No-vig calculator
Remove the margin from a two-way market so both sides sum to 100%, giving the probability estimate implied by the price itself.
No-vig
Remove the margin
Normalising both sides to sum to 100% gives the book's actual probability estimate — the number worth comparing against an exchange.
- Market hold
- 3.63%
- Booked total
- 103.63%
- Fair A
- 57.1% · -133
- Fair B
- 42.9% · +133
1. Convert both sides
Turn each side of the market into implied probability. The two will sum to more than 100%; the excess is the hold.
2. Normalise
Divide each side by the sum. The results are the no-vig probabilities, which is the number worth comparing against an exchange price.
3. Compare
A gap between the no-vig probability and a prediction-market price is a difference of opinion between venues, not a guaranteed edge.
Sources
No source is connected to this section yet. Nothing here should be read as a current factual claim.
This tool takes no external data. It computes only from the numbers you type, in your browser, and nothing you enter is transmitted or stored.