In this post I will be collecting all formulas that may be useful in Betfair trading.

Profit for BACK bet

Profit = Stake * (Odds – 1)

Profit for LAY bet

Profit = Stake

Loss for BACK bet

Loss = Stake

Loss for LAY bet

Loss = Stake * (Odds – 1)

PL = (Stake / 2) * (Odds – 1) – (Stake / 2)

PL = (Stake / 2) – (Stake / 2) * (Odds – 1)

How to calculate LAY stake from given liability

Stake = Liability / (Odds – 1)

How to calculate BACK stake from given target profit

Stake = Target Profit / (Odds – 1)

How to calculate BACK stake for equal greening up. Assuming that you have a lay bet at LayOdds and want to trade out at higher BackOdds to make a situation with equal profit for win and lose results.

LayWinPL = LayStake * (LayOdds – 1)
LayLoosePL = LayStake
BackStake = (LayWinPL + LayLoosePL) / BackOdds

How to calculate LAY stake for equal greening up. Assuming that you have a back bet at BackOdds and want to trade out at lower LayOdds to make a situation with equal profit for win and lose results.

BackWinPL = BackStake * (BackOdds – 1)
BackLoosePL = BackStake
LayStake = (BackWinPL + BackLoosePL) / LayOdds

How to find a chance % of selection to win from it’s odds

Chance = 100 / Odds

How to convert fractions to decimal odds

Fractions: A/B

Decimal = A / B + 1