Inside Mount vs Outside Mount

The call

Inside mount looks tailored and shows off the trim, but it demands adequate depth and an exact width — and every seller applies its own deduction, so you confirm the number against their measuring guide, not ours. Outside mount forgives a shallow or out-of-square opening, blocks more light because it overlaps the frame, and is the move for true room-darkening; the cost is that it covers the trim and reads a little bulkier. Add 2–3 inches of overlap on each side for an outside mount. Whichever you choose, custom blinds are made to size and generally not returnable — measure twice.