How to Calculate Quartz Countertop


Installing a new quartz countertop can greatly enhance the look and functionality of your kitchen. Quartz is an engineered stone made from crushed quartz bound together with resin. It is highly durable, stain and scratch resistant, and available in a wide variety of colors and patterns.

When preparing for a new quartz countertop installation, it is important to calculate the amount of quartz you will need. Accurately measuring your existing countertop and planning for any new sections will ensure you purchase the correct quartz slab size and have minimal waste. This guide will walk you through the key steps for how to calculate the quartz needed for your new countertop.

Measuring Existing Countertop Sections

The first step is to carefully measure each section of your existing countertop that will be replaced with quartz. Here are some tips for getting accurate measurements:

Use a Measuring Tape

Use a metal measuring tape for taking all length and width measurements. Cloth tape measures can stretch over time resulting in inaccurate readings. Measure to the nearest 1/8th inch.

Measure Separate Sections

Break the countertop into distinct sections like island, peninsula, etc. Measure each section individually.

Note Inside Dimensions

For length and width, measure from inside edge to inside edge. This gives the actual surface area.

Measure Overhangs Separately

Measure any overhangs like a bar lip separately from the main surface.

Account for Seams

If your countertop has seams note measurements on each side of the seam.

Mark Drain and Cooktop Cutouts

Identify any areas that will need cutouts for sinks, cooktops, etc. and mark their dimensions.

Be sure to write down all measurements for each section. This will allow you to calculate the square footage later.

Measuring New Sections or Additional Pieces

In addition to replacing existing countertops, you may be adding new sections like a kitchen island. Be sure to take detailed measurements of any new sections that will be installed.

Some best practices for measuring new sections:

  • Mark the overall length and width as well as any overhangs
  • Note interior dimensions of any cutouts
  • For island and peninsula end pieces, measure the side length and depth
  • Measure separations between multiple stacked pieces like a desk area
  • Identify corner pieces and angle measurements

Having all new section dimensions will make it easy to calculate the total slab requirements.

Calculating the Square Footage

With all your measurements handy, you can now calculate the total square footage of countertop needed. Here is the process:

Multiply Length x Width

For each section, multiply the length by the width to get the square footage of that piece.

For example:
Section 1 – Length 96 inches x Width 24 inches = 2,304 square inches

Adjust for Overhangs

Add any overhang measurements to the length or width before multiplying:

Section 1 – Length 96 inches + 12 inch overhang x Width 24 inches = 2,808 square inches

Convert to Square Feet

Once you have the total square inches for each section, divide by 144 to convert to square feet:

Section 1 – 2,808 square inches / 144 = 19.5 square feet

Add Sections Together

Add together the square footage of all sections to get the total.

Section 1: 19.5 square feet
Section 2: 14.25 square feet
Island: 9 square feet
Total = 42.75 square feet

This total square footage amount is what you will use to determine how much quartz to purchase.

Accounting for Seams

Most countertop installations require seams between slabs to accommodate the size limitations of quartz slabs. When calculating, make sure to account for any seams you will need:

  • For standard depth countertops (24-26 inches), plan for 1 seam every 8-10 feet.
  • For extra deep countertops (over 26 inches), plan for a seam every 6 feet.
  • Add 1-2 feet per seam for the amount of overlapped material.

For example, if you have a 10 ft section, you will need to get 2 pieces at 5 ft each with 1 ft of overlap for seaming. This means you should calculate it as 12 sq ft instead of 10.

Planning ahead for seam placement based on your measurements will ensure you get the right quartz slab sizes.

Selecting Slab Sizes

Once you know the total square footage needed, you can select the best slab sizes to purchase. A few tips:

  • Quartz slabs are available in standard widths of 55”, 65” and 73”.
  • Standard lengths range from 110” to 130”. Custom sizes are available.
  • Allow for a 2” overhang on each exposed edge unless planning for a minimal reveal installation.
  • For most efficient use, fit the longest sections across the narrower slab widths.

Using your calculations, play around with different slab size combinations to minimize seams and waste. This will maximize your budget.

Planning for Other Materials

In addition to the quartz slabs, be sure to account for any other materials needed:

Quartz Backsplash

If doing a full quartz backsplash, measure the linear feet needed and add 10-15% for seams and wastage.

Edge Profiles

Factor in extra material if doing special edge treatments like a bullnose. Add up the linear footage.

Support Materials

Account for adhesive, seam kit, and other supplies. Talk to your fabricator about required items.

Getting an accurate quartz measurement along with these extra materials will give you a complete countertop budget.

Factoring in Waste

It is impossible to perfectly plan quartz slab use so that you end up with no leftover materials. When estimating, add a waste factor to give yourself a buffer:

  • Add 15% for simple layouts with few seams
  • Add 20% for more complex designs with multiple seams
  • Add 25% for intricate edge treatments or insets

By overestimating slightly, you end up with extra quartz rather than coming up short. The excess can be used for cutting boards, trivets, soap dishes, etc.

Ordering Your Materials

Once you have your measurements and have added appropriate waste factors, you are ready to place your quartz order.

  • Provide your total square footage amount and the slab size combinations you want.
  • Supply any special instructions like edge profiles or thickness.
  • Order extra as needed for backsplashes and other materials.
  • Confirm timelines – slab fabrication can take a few weeks.

Ordering the properly calculated quartz amount and other supplies well in advance will ensure your project stays on schedule.

Key Takeaways for Calculating Quartz Countertops

Calculating your exact quartz needs may seem complicated but following this process will guarantee you order the right amount:

  • Carefully measure each section and overhang. Convert to square feet.
  • Account for any seams and add material.
  • Select optimal slab widths and lengths for your layout.
  • Factor in extra materials like backsplash, edges, etc.
  • Add appropriate waste factors – 15-25% is typical.
  • Order your materials from a fabricator early.

With detailed measurements and planning, you will purchase just the right quartz amount for a beautiful new countertop installation.

Frequently Asked Questions About Calculating Quartz Countertops

Some common questions that come up when calculating quartz countertops:

How do I account for corners and seams when measuring?

For inside corners or seams, take the measurements for each section right up until the join. Avoid overlaps in your measurements. The fabricator will cut the quartz to fit correctly at corners.

Should I add extra for potential breakage or defects?

The waste factor already builds in a buffer for any potential slab damage or unusable areas. No need to add more unless you have an extremely intricate design.

What thickness quartz should I get?

Standard thickness is 3cm (1.25 inches). Go with a thicker slab of 3.5cm or 4cm if you want a heavier look or will have very heavy use.

Can I use remnants somewhere else if I have leftovers?

You can get creative with extra pieces of quartz! Just make sure to double check on the warranty – some disallow using remnants for certain purposes.

Is there an easy formula I can use?

To simplify calculations, use this rule of thumb: Total square feet x 1.15 x number of slabs needed. This accounts for 15% waste and provides a quick estimate.


Calculating the right amount of quartz for your countertop project involves careful measurement, planning for seams and extras, factoring in waste, and ordering the correctly sized slabs. Following the process outlined in this guide will help you determine the exact quartz countertop square footage required with minimal leftovers. With your materials order placed well in advance, you will be ready for a smooth installation.