How to Make a DIY Upholstered Bay Window Seat Cushion

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One of the easiest and inexpensive ways to update a space can be through the simple addition of upholstered cushions and pillows. But if you truly want to elevate a kitchen or window nook, a great way to make your space cozier is by adding window seat cushions. So here’s a tutorial on how to make your own DIY window seat cushions!

Required Supplies for Your New DIY Window Seat Cushion

  • GeoBella water-resistant, durable upholstery fabric
  • Foam (choose preferred thickness)
  • ½ inch plywood

Tools Needed for This Project

  • Pins
  • Sewing machine
  • Thread
  • Tape measure

Your Step-by-Step Guide to Make a DIY Upholstered Window Seat

Step #1: Choose the Fabric

Here’s where your creativity can take the wheel. Choosing a fabric will be important in terms of style, but don’t forget function. Whether your window seat is in a kitchen or a reading nook, the fabric will need to be strong, durable and water-resistant for all the traffic and spills that will inevitably come. GeoBella Outdoor Fabric is the perfect option for window seat cushions because it possesses all the above qualities, while still offering stylish flair. Browse our durable GeoBella upholstery fabrics perfect for a sturdy DIY window seat.

(The upholstery fabric we used for this project is GeoBella Canvas Marzipan.)

Step #2: Measure Your Bay Window Seat & Chosen Fabric

Measure twice, cut once. It’s important to accurately measure the area of your window seat or bench, in order to create a well-made DIY window seat cushion.

First, find the length of your cushion, by measuring the length of your bench.  Once you have this number, subtract about a half inch, so the cushion isn’t longer than the surface of the window seat. Second, measure the width or depth of your surface, and subtract a half inch again.

Next, take the length and width measurements and add the measured thickness of your foam and plywood + an additional inch, and these will be your measurements for your fabric. These additional inches will allow the fabric to wrap around the cushion. For example, if your foam is 3 inches and your length measurement is 40 inches, then your new measurements will be 40 + 3 + 1 = 44 inches long.

Step #3: Sew the Inseams of Your Window Seat Fabric

Sew down the edge of each end using a ½ inch seam. This will create clean lines, and a secure seal for your fabric on your window seat cushion.

Step #4: Prepare the Seams of the Box Corners for Your Seat Cushion

Now, determine the size of the boxed corner by taking the thickness of your foam and create your boxed corner according to those measurements.

Next, divide this measurement by two. For example, if you want your fabric’s depth to be four inches, 4 divided by 2 is 2.  Then take this measurement and cut squares out of each corner of the fabric.  To follow the example, you would cut a 2 inch by 2 inch square out of the corners of your fabric. Do this for each corner.

Step #5: Sew the Seams of Your Box Corners

Now that you’ve prepared your fabric to make box seams, pinch the top layer of the fabric and pull it over until the sewn seam and desired edge line up exactly. This will create a new corner with the seam running diagonally.

Next, place pins along the seam through all layers of fabric to hold the seam to the desired edge on the opposite side. Sew together.

Step #6: Turn Your Window Seat Pattern Inside Out and Stuff with Foam

Now you can take your fabric, turn it right side out and you should have a cushion covering. Next, stuff with foam.

Step #7: Stitch the Back Seam of Your DIY Bay Window Seat Cushion

Finally, you should have one open seam where you were able to stuff your covering with foam. Sew this seam together.

Et voila! You have your own DIY window seat cushion made and ready to use!

Step #8: Relax on Your New DIY Bay Window Seat Cushion

Consider yourself a professional DIYer? Stock up on GeoBella’s durable, long-lasting upholstery fabric for your next project.

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