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Fair price calculator

Take the site's cut out of a price to see the fair chance of each side.

Free, no account needed. The link keeps your numbers, so you can share them.

One site's prices

Example numbers. Type your own.

Use every side of one bet at one site. Best is a site known for accurate prices (a sharp site, like Pinnacle). Mixing sites gives a wrong answer.

How many sides?

Odds format

Result

The site's cut
3.70%

The chances add up to 103.70%. Everything over 100% is the site's cut, and this takes it out.

Fair chance and fair odds for each side, by way
WaySide 1Side 2
Multiplicative64.29%1.5635.71%2.80
Additive64.81%1.5435.19%2.84
Power65.08%1.5434.92%2.86
Shin64.81%1.5435.19%2.84
Worst caseDefault64.29%1.5634.92%2.86
Side 1 fair odds (worst case)
-180
Side 2 fair odds (worst case)
+186

Worst case adds up to 99.20%, a bit under 100%, because it takes the lowest chance for each side. That is on purpose: a bet only counts as a value bet if it beats every way.

See open both-sides bets (no account needed)

How it works

  1. Type one site's price on every side of one bet: 2 sides, or 3 with a draw.
  2. The calculator adds up the chances the prices imply. Everything over 100% is the site's cut.
  3. It takes the cut out four ways and shows each side's fair chance and fair odds.
  4. It also shows the worst case: the lowest fair chance any way gives.
The formula
p = 1 / decimal odds, S = the sum of every pMultiplicative: p / SAdditive: p - (S - 1) / nPower: p^k, with k set so the chances add up to 100%Shin: solves for the share of informed moneyWorst case: the lowest of the four, side by side
Example

Favourite at 1.50, underdog at 2.70

  1. The implied chances add up to 103.70%, so the site's cut is 3.70%.
  2. Multiplicative: favourite 64.29%, underdog 35.71%.
  3. Power: favourite 65.08%, underdog 34.92%.
  4. Worst case: favourite 64.29%, underdog 34.92%, so fair odds of 1.56 and 2.86.

These are the numbers already in the calculator above.

Questions

What does devig mean?
Taking the vig, the site's cut, out of its prices. What is left is an estimate of the true chance of each side, the fair price. You can compare it with prices at other sites.
Which way is best?
No way is right every time. Multiplicative is the simplest. Power and Shin take more off long shots, which often suits real games. If you are not sure, use the worst case: a bet with value by every way has value by whichever one turns out right.
Can I use prices from two different sites?
No. Use one site's prices on one bet. Two sites' prices together don't show either site's cut. If they add up to under 100%, you have a both-sides bet, not a cut to take out.
Why doesn't the worst case add up to 100%?
Because it takes the lowest fair chance for each side on its own, from whichever way gives it. That makes it a little under 100% on purpose, so no side's chance is overstated.
Which site's prices should I use?
A sharp site: one known for accurate prices. It takes large bets and moves its prices quickly. WynFynd uses Pinnacle's prices as its fair price by default.

Learn the idea

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