The fair price: take out the cut
How we take the betting site's cut out of a price to find the true chance.
3 min readChecked on Oct 31, 2026
A site's prices include its cut. To use them as a fair price, you take the cut out first. This is called devigging (vig is another word for the site's cut).
WynFynd does this to the prices of a site known for accurate prices (a sharp site, like Pinnacle). That gives the true chance of each side. Then we look for other sites paying more than that.
The simple case
1.91 on both sides
- Each side means 1 / 1.91 = 52.36%.
- Together that is 104.71%. The extra 4.71% is the site's cut.
- Take it out evenly and each side is 50%. The fair odds are 1 / 0.50 = 2.00.
When both sides have the same price, every way agrees. When one side is a favourite, they don't. Nobody knows exactly how a site spreads its cut between the favourite and the underdog.
Four ways to take out the cut
- Multiplicative: shrink every side by the same share. Divide each chance by the total. Simple and very common.
- Additive: take the same amount off every side. The underdog keeps a little less than with multiplicative.
- Power: raise each chance to the same power until they add up to 100%. It takes more off long shots, which usually carry more of the cut.
- Shin: a model that assumes some of the money comes from people with inside information. Popular with professional bettors.
| Way | Favourite | Underdog |
|---|---|---|
| Multiplicative | 64.29% (1.56) | 35.71% (2.80) |
| Additive | 64.81% (1.54) | 35.19% (2.84) |
| Power | 65.08% (1.54) | 34.92% (2.86) |
| Shin | 64.81% (1.54) | 35.19% (2.84) |
| Worst case | 64.29% (1.56) | 34.92% (2.86) |
The prices add up to 103.70%. The four ways give the underdog anything from 34.92% to 35.71%. That gap looks small. It can decide whether a bet has value.
Is 2.85 on the underdog a value bet?
- Another site offers the underdog at 2.85. Value = fair chance x 2.85 - 1.
- With each way's fair chance: Multiplicative +1.79%, Additive +0.28%, Power -0.48%, Shin +0.28%.
- Three ways say it is a value bet. The power way says it is not.
- The worst case (34.92%) gives -0.48%.
Worst case: WynFynd's default
WynFynd takes the lowest fair chance any way gives each side. This is called the worst case. A bet then only counts as a value bet if it beats every way. So its value is never overstated.
In the example, 2.85 on the underdog is not a value bet by the worst case. WynFynd would not send it. Pro members can pick a single way instead, in Alerts.
Worst-case chances add up to a little under 100% (99.20% here). That is expected: each side gets its own most careful number.
Things to watch
- Only use one site's prices on one bet. Mixing two sites' prices gives a total that is nobody's real cut.
- Use a site known for accurate prices. A slow site, or one with a big cut, gives a fair price only as good as its prices.
- Three-way bets (home, draw, away) work the same way, with three prices.
- Prices move. A fair chance from an hour ago may not be fair now.