Free planning tool
Countertop area calculator
Calculate countertop square footage or worktop area in m². Add straight runs, L-shaped corners and islands, then save a clear breakdown of your measurements. Free, with no sign-up.
Your measured area
One L-shaped run
Area for planning. Slab quantity, seams and installation costs need a separate estimate.
L-shaped run 1
Top view · to scaleFocus a measurement field to highlight its dimension. Separate sections are added together; they must not overlap.
Net area is a geometry check, not the amount of material to order. Cutout locations and spacing are not checked.
How to use the countertop calculator
- Choose centimetres or inches. Measure the complete surface, not just the cabinet boxes.
- Choose a straight run, island or L-shaped section. For an L, measure both full outside lengths and both depths. The shared corner is subtracted once.
- Add separate runs or islands. For a U-shape, split your sketch into three rectangles that meet without overlapping. Use the shorter, non-overlapping lengths.
- Optionally record rectangular cutouts. Save, share or print the total and section breakdown for your next planning conversation.
Need help with your sketch? Follow our countertop measuring guide for examples, overhangs and common corner mistakes. Planning an island footprint? Use the kitchen island size calculator first.
Try a worked example
| Example | Gross area | Net after cutout |
|---|---|---|
| 120 × 25.5 in straight run | 21.25 sq ft | 21.25 sq ft |
| L: 300 × 60 + 240 × 60 cm, shared 60 × 60 corner | 2.88 m² | 2.88 m² |
| Same L + 180 × 90 cm island; 50 × 40 cm cutout | 4.50 m² | 4.30 m² |
Formulas and assumptions
Rectangle: length × depth.
L-shape: (A × D) + (B × E) − (D × E). Both outer legs include the corner; it is counted once in the result.
Conversion: square inches ÷ 144 = square feet. Square centimetres ÷ 10,000 = square metres. One inch is exactly 2.54 cm.
Net: gross area − the sum of rectangular cutout areas. Calculations use unrounded values; displayed results are rounded to two decimal places.
This tool supports up to eight sections and four rectangular cutouts per section. Dimensions must be positive and no greater than 2,000 cm (787.4 in). It checks whether a cutout can fit within a rectangular run in either orientation, and whether combined cutout area is smaller than that section. It does not place cutouts or check their spacing, overlaps, structural support or minimum edge distances. Round or irregular surfaces need their own measured drawing.
Common questions
Do I subtract the sink or cooktop?
The calculator keeps the full area as its primary result and optionally shows net area after rectangular openings. A fabricator still needs material around an opening; removing it does not automatically reduce the slab requirement or quote.
How do I enter feet and inches?
Select inches and convert feet to inches first: 10 ft 6 in becomes 126 in. You can enter decimals, such as 25.5 in. Metric inputs are in centimetres, so enter 300 for a 3 m run.
Are backsplash and waterfall panels included?
Only the sections you enter are included. This tool is designed for horizontal countertops. Keep vertical splashbacks and waterfall panels on a separate list so the surface total stays clear. Their material, seams and edge treatment need a separate specification.
Can this tell me how many slabs to buy?
No. Surface area alone cannot determine slab count. Slab dimensions, usable yield, defects, vein direction and where pieces can join change the cutting layout. Take your saved measurements to a fabricator for templating and a material estimate.
Measurement sources
The rectangle method follows the Lowe’s countertop measure guide and The Home Depot preliminary measurement worksheet. Our examples and diagram geometry are original calculations. The older Home Depot worksheet is used for its measurement method, not for current prices or service terms.
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