What is the formula for shares allotment in an IPO?

Once the subscription closes, one can make out probability of allotment. e.g. XYZ ltd. issues IPO with lot size of 60, let's assume that retail subscription was 5 times after closure. So it's clear that people who applied for 5 lots will definitely get atleast 1, but for those who applied for less than 5 lots it will be done on lottery basis. i.e. for those who applied for say 1 lot 1 of every 5 will get allotment. For detail knowledge of shares allotment formula, please refer Basis of allotment document of recent IPO's. /report/ipo_basis_of_allotment_list/7/ Answered by Mr Manoj