Price band is the rupee range within which applicants can bid for IPO shares — for example ₹290-310. The band is announced in the RHP a few days before the issue opens. The width of the band is typically narrow — under 20% — to give the market a focused price discovery exercise rather than a wide-open guessing game.
Retail investors bid at cut-off (effectively the upper band). NII / HNI and QIB bidders specify a price within the band. The final issue price — also called the cut-off price for that issue — is the highest price at which the entire offering can be sold across all categories, based on the book the BRLM has built during the subscription window.
Issue size (in rupees) is calculated using the final cut-off price, not the upper or lower band. The RHP discloses issue size in terms of number of shares offered; the rupee value follows once price discovery completes.