How to use this calculator
- Measure the run. Length of the wall the backsplash will cover, in feet. For an L-shaped kitchen, add the two runs.
- Pick a height. Standard kitchen backsplash: 18 inches (between counter and upper cabinets). Stove area sometimes goes to ceiling.
- Choose tile size. Subway tile (3×6"), penny round, mosaic, or large-format. The calculator returns box count for each.
- Add 15% waste. Backsplashes have many cuts. Most pros buy 15% extra; mosaics with an irregular layout buy 20%.
Formula
Square feet = (Run length × Height in feet) + 15% waste
Worked example
A 12 ft kitchen backsplash at 18 in tall is 18 ft². Add 15% waste = 20.7 ft². For 3×6" subway tile (8 tiles per ft²), that is 166 tiles ≈ 7 boxes of 24. Plus a 5-gallon pail of mastic and 25 lbs of grout.
Tips for accurate results
- Order all the tile from one dye lot to avoid color variation between boxes.
- For a window in the backsplash run, measure the openings carefully — many tiles cut at odd angles.
- Use mastic adhesive for kitchen backsplashes; it grips faster than thinset and avoids drips down walls.
- Plan the layout dry first. Center the focal point (above the cooktop) so cut tiles end at corners.