How to calculate countertop square footage
Countertop material is priced and ordered by the square foot, so the number you need is the surface area of every counter run. For a straight run:
Square feet = Length (in) × Depth (in) ÷ 144
- Measure each counter run along the wall, in inches. Standard kitchen counters are 25 inches deep (24-inch cabinets plus a 1-inch overhang).
- Multiply length × depth for each run and divide by 144 to convert square inches to square feet.
- Add islands, peninsulas, and backsplash strips separately, then sum everything.
- Add a waste buffer: about 10% for laminate and butcher block, 15–20% for granite and quartz slabs.
Worked examples
| Layout | Runs | Calculation | Area |
|---|---|---|---|
| Straight galley wall | 120 in × 25 in | 3,000 ÷ 144 | 20.8 sq ft |
| L-shaped kitchen | 120 × 25 in + 96 × 25 in | 5,400 ÷ 144 | 37.5 sq ft |
| Kitchen island | 72 in × 36 in | 2,592 ÷ 144 | 18 sq ft |
| Bathroom vanity | 60 in × 22 in | 1,320 ÷ 144 | 9.2 sq ft |
L- and U-shaped counters
Measure each leg to the wall, not to the inside corner, then subtract the overlapping corner square once (25 × 25 in ≈ 4.3 sq ft) so it isn't counted twice. For a U-shape, subtract two corner squares.
Standard countertop dimensions
- Kitchen counter depth: 25 in (63.5 cm)
- Bathroom vanity depth: 19–22 in
- Island seating overhang: 12–15 in beyond the cabinet
- Backsplash strip (4 in high): length in inches × 4 ÷ 144