How to measure a countertop
Sketch the kitchen from above and split the counter into rectangles. A corner belongs to one run or the other, never both, so decide which one takes it and mark that on your sketch. Then measure each rectangle's length, and its depth from the wall to the front edge, in inches. Lowe's guide reminds you to measure bar tops, islands and peninsulas as well, since they are easy to miss.
Measure the counter you have, not the cabinet beneath it, because the top overhangs. Lowe's calls 26 inches standard, while other pages say 25 to 25.5, which is why this calculator asks. An island's depth should include any seating overhang.
Leave the sink and cooktop in. Lowe's guide tells you to include those spaces, and it shows no subtraction, because the hole is cut from a piece you bought. A fabricator will template your actual kitchen before cutting, so this figure is for pricing and not for ordering.
A worked example
Here is an L-shaped kitchen with runs of 10 and 6 feet, a 6 by 3 foot island and a 4 inch backsplash along the walls. These lines come from the same formula the calculator above runs.
L-shape with a 6 by 3 ft island
- Runs: (120 + 72) × 26 ÷ 144 = 34.7 sq ft
- Island: 72 × 36 ÷ 144 = 18.0 sq ft
- Backsplash: 192 × 4 ÷ 144 = 5.3 sq ft
- To price: 58 sq ft, rounded up
- Slabs at the least: 2 of 47.02 sq ft
The slab count is the bare minimum, by area. Your fabricator also has to fit the shapes on the slab, so that the longest piece runs with the slab and the grain works. For the full price of the job, the kitchen remodel cost calculator sets this against the rest of the room, and the tile calculator handles a tiled backsplash.
Counter area for common kitchens
These all use a 26 inch depth and a 4 inch backsplash along the wall runs. Standard slabs are Cambria's 47 square foot size, counted at the bare minimum.
| Kitchen | Counters | Backsplash, 4 in | To price | Standard slabs |
|---|---|---|---|---|
| Galley, one 10 ft run | 21.7 | 3.3 | 25 | 1 |
| Two 8 ft runs | 34.7 | 5.3 | 40 | 1 |
| L-shape, 10 and 6 ft | 34.7 | 5.3 | 40 | 1 |
| L-shape with a 6 by 3 ft island | 52.7 | 5.3 | 58 | 2 |
| U-shape, 10 and 12 ft | 47.7 | 7.3 | 55 | 2 |
| Large, 14 and 10 ft, with an 8 by 3 ft island | 76.0 | 8.0 | 84 | 2 |
Mistakes that change a quote
- Measuring the cabinet. The top overhangs it, so the depth you want is from the wall to the front edge.
- Counting a corner twice. Where two runs meet, only one of them owns the corner.
- Assuming no seams. Cambria says its counters do not always come without a join, and a piece longer than the slab has to have one. Ask where.
- Forgetting the other charges. Pricing varies by fabricator, edge profile and cutouts, and removing the old top often costs extra.
- One slab size for every stone. Sizes depend on the brand and even the design, so check yours.
Questions
How do I measure countertops for quartz?
Measure each run along the wall and from the wall to the front edge, then multiply and divide by 144. Include spaces for the sink and cooktop, and measure bar tops, islands and peninsulas, as Lowe's guide says. A fabricator will template it before cutting.
How big is a countertop slab?
Cambria's standard slab is 122 by 55.5 inches, about 47 square feet, and its jumbo is 132 by 65.5 inches, about 60 square feet. Other brands differ, and some designs come in only one size, so ask your fabricator what is available.
How many slabs do I need for my kitchen?
At the least, divide your total area by the slab's: a 65 square foot kitchen needs 2 standard slabs. The real number can be more, because the pieces have to fit, with grain and seams in the right place. Only a fabricator can settle it.
Is backsplash included in countertop square footage?
Not unless you add it, and the Lowe's form asks for it separately. A 4 inch backsplash along 16 feet of wall adds about 5.3 square feet. If it is tile, leave it out here and use the tile calculator for it.
How much does a quartz countertop weigh?
About 15 pounds per square foot at 3 cm thick, by Cambria's sheet, with 2 cm at about 10 pounds. A 40 square foot kitchen in 3 cm is about 600 pounds, which is why installers need to check the cabinets and bring a crew.
Do I take off the sink cutout?
No, leave it in. Lowe's guide shows no subtraction, and the sink hole is cut from a piece you have already paid for. Fabricators may charge separately for each cutout, so ask, because that is not included here.
This countertop area is a planning estimate, and the slab count is only the area divided by a slab, because fabricators nest and join pieces as they see fit. A fabricator will template your kitchen and set the final figure. Check slab sizes with your supplier, since makers vary, and read the label on any sealer or adhesive.
Sources and review
- Kitchen countertop measure guide, Lowe's, no date shown, read November 2026.
- Slab product information, Cambria, 2024.
- What to know about quartz surface seams, Cambria, no date shown, read November 2026.
Checked in November 2026. Spotted a wrong number? Report it and it goes in the corrections log.
How this is calculated
Every figure below is read from the code that produces the answer, so what is written here is what the calculator ran. The constants were last checked against their sources in November 2026.
The arithmetic
Area
Square feet = Length × Depth ÷ 144, for each piece
- 144
- Square inches in one square foot
Worked through: 120 × 26 ÷ 144 = 21.67 sq ft
Slabs, at least
Slabs = Total area ÷ Slab area, rounded up
- Slab area
- 122 × 55.5 ÷ 144 = 47.02 sq ft for Cambria's standard
Worked through: 65 ÷ 47.02 = 1.38, so at least 2 slabs
The constants, and where they come from
SLABS
Published figureSlab sizes offered by one maker, in inches
- standard
- length 122, width 55.5
- jumbo
- length 132, width 65.5
Applies to: Cambria quartz. Other makers and even other designs differ, so ask
Source: Slab product information, Cambria, published 2024, read 2026-11. This source is about 2 years old, and it is the one the figure rests on.
Cambria prints standard as 122 by 55.5 inches, nominal 47 square feet, and jumbo as 132 by 65.5, nominal 60. The slab count is only the area divided by this, with no allowance for seams or nesting, because no source gives one.
POUNDS_PER_SQ_FT_3CM
Published range, narrowedWeight of 3 cm quartz, in pounds per square foot
Applies to: Cambria quartz at 3 cm. Thinner slabs are lighter
Source: Slab product information, Cambria, published 2024, read 2026-11. This source is about 2 years old, and it is the one the figure rests on.
Cambria's sheet lists 15, 10 and 6 pounds per square foot for 3, 2 and 1 cm, and we matched them up by the layout of its table.
SQ_IN_PER_SQ_FT
DefinitionalSquare inches in one square foot
Applies to: Definitional, everywhere
Source: Kitchen countertop measure guide, Lowe's, no date on the page, read 2026-11.
Twelve inches in a foot, and an area is a length times a length, so 12 × 12 = 144. Lowe's guide divides by 144 in just this way.
What the labels mean
- Published figure:
- taken directly from the source named beside it.
- Published range, narrowed:
- a source publishes a range and this calculator uses a representative value from it.
- Definitional:
- true by definition, like the number of inches in a foot, so there is nothing to cite.
If a figure here looks wrong, it may be. Tell us what you found and we will check it against the source and publish a correction if it needs one. How constants are chosen and how often they are reviewed is set out in our methodology.
How to use the countertop square footage calculator
- 1
Sketch the kitchen, marking every run, island and bar top
- 2
Measure each piece's length and depth, from the wall to the front edge
- 3
Add a backsplash height if it will be the same stone
- 4
Read the square feet to price, and the slabs at the least
- 5
Get a fabricator to template it, since they set the final figure
What this calculator assumes
Every estimate here rests on the assumptions below. Where your job differs from one of them, the figure will differ too.
- Sink and cooktop spaces are left in the area, as Lowe's guide shows, because they are cut from a piece you have paid for
- Depth is entered by you, because sources differ between 25 and 26 inches
- Slabs are counted by area alone, with no allowance for seams, because no source gives one
- Cambria's sizes are examples, and other makers and designs differ
Pro tips
- See the actual slab if it has movement, because the pattern changes where seams look best
- Ask how your fabricator charges for cutouts, edges and removing the old top
- Confirm the sink and appliance choices before the template visit