Betting (bookmaker, bettor) odds calculator

The current web page allows you to calculate margin (vigorish) and overround for bookmakers odds, to evaluate the proposed betting markets. Also a bettor (a professional player who bets on sports) has the ability to obtain true (fair) odds and calculate stakes (amounts) for the betting arbitrage (surebets).

Coef, C, C1, C2, C3, ... C9 - bookies odds in decimal format (coefficients; all >= 1)
Prob, P, P1, P2, P3, ... P9 - probabilities

⊕, ⊖ - bookmakers odds Sum and Difference

Margin (M) and Overround (O) calculation formulas:

M = 1 - Odds*Prob, Odds = (1 - M)/Prob

M = 1 - 1/(1/C1 + 1/C2 + ... + 1/CN), when P1 + P2 + ... + PN = 1

O = M/(1 - M), M = O/(1 + O)

Set two-way (for example: W1, W2X) or three-way (for example: W1, W2, X) odds and sum of stakes (total bid) to calculate

Stake - stake (wager, bet) amount

Calculation equations:

Odds_1*Stake_1 = Odds_2*Stake_2 [= Odds_3*Stake_3] = (1 - M)*Sum_of_Stakes