Countertop Square Footage Calculator
Countertops are sold and priced by the square foot, but you measure them in inches, so the job is to multiply length by depth for each section, sum them, and convert to square feet. A waste allowance covers seams, sink and cooktop cutouts, edge profiling, and slab matching. Enter the length and depth of up to two sections, such as a main run and an island, plus a waste percentage. This calculator returns the net area, the area to order with waste, and the square inches total.
Countertop area formula
Section area (sq in) = length * depth
Total sq in = section 1 + section 2
Net area (sq ft) = total sq in / 144
Area to order = net area * (1 + waste / 100)
Length times depth gives each section in square inches. Dividing the sum by 144 converts to square feet. The waste factor covers seams and cutouts.
Countertop ordering tips
- Standard counters are about 25 to 26 inches deep over a 24-inch cabinet.
- There are 144 square inches in a square foot.
- Stone needs more waste for grain matching than laminate.
- Include sink and cooktop cutouts in your waste allowance, not as deductions.
- ICC residential and GSA construction standards apply to fixed casework in the US.
Countertop square footage: frequently asked questions
How do I calculate countertop square footage?
Multiply the length by the depth of each countertop section in inches, sum the sections, then divide by 144 to convert square inches to square feet. Add a waste allowance for cuts, seams, and template adjustments.
What is the standard countertop depth?
A standard kitchen countertop is about 25 to 26 inches deep, sitting over a 24-inch base cabinet with a small overhang. Enter your actual depth in inches; this calculator does not assume a fixed value.
How much waste should I add for countertops?
Fabricators often add around 10% to 20% for seams, sink and cooktop cutouts, edge profiling, and slab matching. Stone in particular wastes more because of grain matching. This calculator lets you set the percentage.
Why convert square inches to square feet?
Countertops are usually priced per square foot, but measured in inches. There are 144 square inches in a square foot, so dividing the total square inches by 144 gives the area in square feet for ordering and pricing.
Can I add an island or a second run?
Yes. This calculator has two sections so you can enter a main run and an island or return. Sum more sections by hand if you have a complex layout, using the same length times depth divided by 144 method.
Official sources
- U.S. General Services Administration: Design and construction standards.
- U.S. National Institute of Standards and Technology: Office of Weights and Measures (unit conversion).
Reviewed by the CalculatorHub team, edited by James Graham, 16 June 2026. See our methodology.