How to Measure Subway Tile Backsplash

Measuring and calculating the square footage needed for a subway tile backsplash is an important part of planning your kitchen or bathroom remodel. With some simple math and measurement techniques, you can accurately determine how many subway tiles you need to purchase. Getting the measurements right will ensure you buy enough tiles the first time and avoid extra trips to the tile store.

Why Proper Measurement Matters

When undertaking a new backsplash installation or renovation, measuring correctly makes a big difference in achieving the desired outcome. Here are some key reasons accurate measurements are essential:

  • Avoid buying the wrong quantities of tile – Precise calculations allow you to purchase the right amount of subway tile and prevent coming up short or having costly leftovers.
  • Minimize wastage – Good measuring helps reduce tile cuts and waste. This saves you money and helps the environment.
  • Achieve the desired visual look – Proper measurement ensures tiles are spaced evenly and align correctly for the optimal aesthetic.
  • Save time – Reduces back and forth trips to the tile shop for adjustments or supplemental purchases.
  • Prevent headaches down the road – Accurate calculations lead to a smooth installation process without nasty surprises or complications.

Taking the time to measure thoughtfully and develop a clear tile plan ultimately leads to a stunning, professional-looking subway tile backsplash you will admire for years to come.

How to Calculate Square Footage for Tile Backsplash

To determine the required square footage of subway tile, follow these simple steps:

1. Measure Surface Area Height x Width

  • Use a measuring tape to measure the height of the backsplash area in inches from the countertop to the bottom of the upper cabinets.
  • Next, measure the length of the backsplash area in inches across the bottom edge along the countertops.
  • Multiply these two measurements together to calculate the overall surface area.

2. Calculate Surface Area in Square Feet

  • Take the surface area total from Step 1 measured in inches.
  • Convert to square feet by dividing by 144 (the number of square inches in a square foot).

This final number gives you the estimated square footage of tile needed to cover the backsplash area.

As an example:

  • Height of backsplash: 18 inches
  • Width of backsplash: 120 inches
  • Surface area: 18 x 120 = 2,160 square inches
  • Convert to square feet: 2,160/144 = 15 square feet

So for this sample backsplash, you would need approximately 15 square feet of subway tile.

3. Factor in Grout Joints and Wastage

Once you know the estimated tile area, add a buffer for the grout joints and tile cuts.

  • For grout joints, assume 1/16 of extra space for every 12×12 inch tile.
  • For waste factor, add 5-10% more tile than calculated area.

Applying the grout and waste factors, our 15 sq ft backsplash example would need:

  • 15 sq ft tile area
  • Plus 1/16, or 0.0625 sq ft for grout joints
  • Plus 10% waste factor, 1.5 sq ft
  • Total tiles needed = 16.56 sq ft

Always round up to the nearest full box when purchasing tiles.

Measuring Tile Square Footage

When buying subway tile, it is sold by the square foot, so knowing accurate measurements is key. Here are some tips on calculating tile square footage:

  • Measure the length x width of each tile in inches.
  • Convert square inches to square feet by dividing by 144.
  • Multiply this individual tile square footage by the total number of tiles needed.

For example, a typical 3×6 subway tile:

  • Width = 3 inches
  • Length = 6 inches
  • Area = 3 x 6 = 18 square inches
  • Converted to square feet = 18/144 = 0.125 sq ft per tile

If you need 300 tiles, multiply:
300 tiles x 0.125 sq ft per tile = 37.5 square feet

Round up to the next full box size and purchase accordingly. Measure carefully, account for pattern layouts, and plan for extras.

Find Square Footage Using Tile Dimensions

For a simpler square footage calculation, you can use the physical tile dimensions rather than taking detailed room measurements.

This involves:

  • Multiplying the height x width of each subway tile in inches.
  • Adding up the totals for all tiles needed.
  • Converting from square inches to square feet.

For instance:

  • 300 tiles needed
  • Each tile = 3 x 6 inches
  • So 300 tiles x (3 x 6) = 5,400 square inches
  • Convert to square feet = 5,400/144 = 37.5 square feet

This shows the same square footage required without measuring the whole installation area directly.

Knowing the exact tile dimensions makes it easy to determine overall square footage. Just multiply the individual tile size by total tiles required.

Measure Carefully for Accurate Calculations

Carefully following measurement best practices ensures you calculate subway tile square footage precisely:

  • Use a quality metal measuring tape for accuracy. Laser measures also work well.
  • Measure multiple spots at top, middle, and bottom and average the results.
  • For height, measure from countertop to bottom of upper cabinets.
  • Measure width across the countertop frontage needing tile.
  • Take photos of measurements for later reference.
  • Double-check all calculations.
  • Round up estimates to the nearest 1/4 tile to allow a margin of wastage.
  • Have décor elements like backsplashes professionally measured if unsure.

Taking extra time to measure correctly makes a big difference in getting your math right. Avoid shortcuts or estimating—precise tile calculations lead to backsplash success.

Tips for Measuring Tricky Backsplash Areas

Many backsplashes have an irregular shape or angled surfaces that make getting accurate measurements tricky. Here are some tips for handling unique backsplash measuring challenges:

Measure Around Obstructions

  • For protruding corners or soffits, take measurements in sections and tally the total.
  • Use a contour gauge to transfer exact shapes and outlines.

Account for Angle Walls

  • For any angle greater than 90 degrees, measure height and width separately.
  • Use the respective dimensions to calculate each wall section independently.

Consider Backsplashes with Open Shelving

  • Take measurements of the area getting tile only, excluding open sections.
  • Calculate separate sections divided by shelving gaps for the math.

For Curved Backsplashes

  • Use a flexible measuring tape to follow the curve contours precisely.
  • Note measurements at regular intervals along the curve.

Around Outlets or Obstacles

  • Measure segments around outlets or appliances individually.
  • Make tile cuts to fit those sections later during installation.

With extra care and detail, even complex backsplashes can be measured accurately. Take your time and account for every angle and curve.

Measure Existing Tile for Replacement

When retiling or replacing a backsplash, measuring the existing tile is easy. Follow these steps:

  • Remove a tile and measure the length, width, and thickness.
  • Count the total number of tiles needed for full coverage.
  • Note the size and color for matching.
  • Measure the area getting retiled if less than the full backsplash.
  • Account for 10% overage just as with new installs.
  • Use a tile gauge to confirm exact sizing if the original size is unclear.

Having the original tile makes it simple to calculate how many replacements you need. Carefully remove samples, record measurements, and use for comparison when purchasing.

Apps and Technology to Measure Backsplash Tile

Beyond manual measurement methods, technology can also help calculate your backsplash tile needs:

  • Smartphone apps like MagicPlan use AI to auto-measure rooms from photos.
  • Digital measuring tools quickly provide precise room dimensions.
  • Online tile calculators allow you to input room size and tile dimensions to estimate totals.
  • Design software like Tile Studio can map out backsplash patterns and specify quantities.
  • Use a laser level to mark layout lines and get clean height and width measurements.

Combining manual measuring with digital tools provides added convenience and accuracy for your backsplash tile math.

Ordering the Right Amount of Subway Tile

Once you’ve used the above techniques to accurately measure and calculate the backsplash area, follow these tips when ordering materials:

  • Round up the total square footage to the nearest quarter or half box.
  • Purchase extra tiles, up to 10% over the calculated amount as spares.
  • Match brand, color, size and style of existing tile if swapping out damaged tiles.
  • Buy all tiles needed for the project at once to guarantee matching dye lots.
  • Get extra matching grout for re-grouting over time as needed.
  • Confirm return policies in case you end up with unused extras.

Careful measurement coupled with smart ordering provides everything needed to complete your backsplash beautifully.

Preparing the Surface for Installation

Once materials are purchased, proper preparation is crucial for achieving a flawless finished backsplash:

  • Clean the surface thoroughly – Remove existing wallpaper, grease, and grime so the tile adheres well.
  • Sand glossy paint for better bonding if tiling over paint.
  • Seal porous drywall using a drywall sealer for a smooth finish.
  • Apply any waterproofing needed according to product instructions.
  • Mark plumb lines as guides for the first tile row using a level.

Taking time to prep ensures the tile goes on cleanly and lasts for years of beauty and function.

Step-by-Step Subway Tile Backsplash Installation

Once preparation is complete, follow these step-by-step instructions for achieving a stunning DIY subway tile backsplash installation:

1. Determine Tile Layout

Decide on the pattern and orientation of your tile design. Typical options include:

  • Standard brick pattern
  • Horizontal stacked
  • Diagonal herringbone
  • Vertical stripes
  • Geometric designs

This will inform cutting needs and overall installation technique.

2. Mix Thin-set Mortar

Prepare thin-set mortar adhesive according to package directions. Maintain an even consistency without lumps for best adhesion.

3. Apply Thin-set Mortar

Use a notched trowel held at a 45° angle to evenly spread the thin-set adhesive on the wall area. Apply 1-2 square feet area at a time to prevent premature drying.

4. Place the First Tile

Beginning with the bottom corner, press the first tile firmly into the thin-set adhesive with a slight twisting motion. Align with guide lines. Use spacers around edges.

5. Lay Remaining Tiles

Work row by row, bottom to top, setting tiles into place gently but firmly. Check alignment often using a level and make any necessary adjustments.

6. Cut Edge and Angle Tiles as Needed

Use a wet saw or tile cutter tool to trim tiles to fit edges and corners neatly. Grind the cut edges smooth.

7. Allow Thin-set Mortar to Cure

Let the thin-set adhesive cure fully per manufacturer directions, usually about 24-48 hours. Avoid disturbing or grouting tiles during this time.

8. Mix and Apply Grout

Prepare grout per package instructions and apply between tile joints, cleaning excess away with a sponge. Allow grout to cure properly before sealing or using.

9. Seal & Enjoy Your New Backsplash

Apply grout sealer once fully cured and buff surface for sheen. Then sit back and admire your stunning, professional-looking subway tile backsplash!

Taking it step-by-step ensures a successful installation and stunning backsplash design feature.

FAQs About Measuring Subway Tile Backsplashes

How many square feet are in a box of subway tile?

Subway tile boxes contain a standard 10 square feet of tile, though larger options like 15 sq ft boxes are also available. Measure your backsplash size in square feet to know how many full boxes to purchase.

What size notch trowel do I need for subway tile?

Use a 1/4 x 3/8 inch square notch trowel for optimal thin-set adhesion on standard subway tile backsplash installations. The ridges create just the right amount of mortar thickness.

How are subway tiles measured?

Subway tiles are measured by their length x width dimensions in inches, such as a standard 3×6 subway tile meaning 3 inches wide by 6 inches long. Use these dimensions to find the tile square footage.

Can I install a backsplash over existing tile?

Yes, it is possible to install a new backsplash over existing tile. The surface must be properly prepped and may require use of a membrane or adhesive specifically formulated for tiling over tile.

How long does thin-set take to dry before grouting?

Allow thin-set adhesive to cure for 24-48 hours before applying grout on a subway tile backsplash. This ensures a strong bond and prevents slippage or cracks between tiles.


Measuring and calculating your subway tile backsplash area properly takes planning, precision, and attention to detail. Following the techniques outlined above will help you get accurate measurements, purchase the correct tile quantities, and achieve impressive installation results. A stunning backsplash starts with measuring right. Use these tips to get your project mapped out and ensure tile purchasing and installation success. With some careful math and tile layout considerations, you’ll gain a gorgeous, professional-looking backsplash you’ll love.