Estimate the cost of printing photos at different sizes.
Photo printing is priced per print by size, and the size steps are steeper than the area suggests — a 10 by 8 is four times the area of a 6 by 4 but often ten times the price, because the larger sizes are treated as a premium product. A premium or lustre finish adds roughly 40 percent per print. Delivery is a fixed charge, so its share falls sharply with order size: it can be a third of a small order and negligible on a large one, which is why batching prints pays.
Unit price
Price per print = listed price for the size x 1.4 if a premium finish is chosen
Order total
Total = price per print x number of prints + delivery charge
Rarely for photographs. Ink and photo paper together commonly run above lab prices for 6 by 4, before counting the printer itself. Home printing wins on immediacy and on very small quantities where delivery dominates.
Because delivery is fixed. Ten prints with a 3.99 delivery charge cost about 0.54 each all-in; two hundred cost about 0.16, and the prints themselves have not changed price.