Calculate savings during a game store sale.
Store sales are easiest to judge by wishlist rather than by title: the full-price total is the baseline, the average discount sets the sale total, and any wallet balance reduces the cash actually leaving your account. The average cash per title is the number that keeps a sale honest — a long wishlist at a deep discount can still add up to more than a monthly entertainment budget.
Sale basket saving
Sale total = titles x full price x (1 - discount/100); cash due = max(0, sale total - store credit); saved = full-price total - cash due
Only against titles you were going to buy anyway. Discount-driven purchases of games you never play cost money rather than saving it, which is why the cash-due figure is shown separately.
It reduces cash out but was already money you owned. Keeping it separate from the discount avoids double counting the benefit.
Historically discounts on older titles keep deepening, so patience usually pays. Compare the current average discount against what the same titles reached in previous sales.