Estimate the cost to frame a picture or poster.
Framing is priced on two different geometries. Moulding is sold by the foot and follows the perimeter, so it scales linearly with size. Glazing is priced by area and therefore scales with the square of size, which is why doubling the dimensions roughly doubles the moulding and quadruples the glass. Both are measured to the outside of the mount border, not the artwork, so a generous mount adds cost on both fronts — a 2.5 inch border on a 20 by 16 print adds nearly two feet of moulding.
Frame geometry
Outer size = artwork + 2 x mount border; perimeter feet = 2 x (outer width + outer height) / 12
Cost
Total = perimeter feet x moulding rate + outer area in square feet x glazing rate + labour
Because it enlarges the frame on both axes, so it pays for extra moulding on all four sides and extra glazing across the whole added area. Reducing a border from three inches to two on a large piece can save a fifth of the cost.
Acrylic is lighter, safer and usually cheaper to ship but scratches easily; glass is clearer and more scratch-resistant but heavy and fragile above about 20 by 30 inches. Enter whichever rate applies.