How to measure a kitchen backsplash
A kitchen backsplash is usually a simple rectangle, but it can get complicated by the area behind the stove or sink.
The standard 18-inch rule
The standard distance between a kitchen countertop and upper cabinets is 18 inches. Measure the total length of your countertop in inches, and multiply by 18 to get the area in square inches. Divide by 144 to get square feet.
Behind the stove
If your backsplash continues up behind the stove to meet a range hood, you need to calculate this extra rectangular area. Measure the width of the space (usually 30 or 36 inches) and the extra height from the bottom of the upper cabinets to the bottom of the hood. Add this to your total area.
Outlets and windows
Do not subtract area for electrical outlets — the area is too small to matter and cutting around outlets actually produces waste. If you have a large window over the sink, you can subtract its area, but it's often safer to just ignore it and treat the extra tile as a safety buffer.