How to Sew A Half Circle for a Scalloped Border

I had never thought of sewing half circle blocks until I wanted to add a scalloped border to this wall hanging I made – look how cute it turned out! I almost wish I had used a solid color to help the scalloped border pop, but this black floral fabric was really calling to me. Sewing curves can be tricky, but they just take practice! If you’ve ever sewn a garment with a set-in sleeve, sewing these half circle blocks reminds me of that – just on a much smaller scale.

In this tutorial I walk through my process of making this scalloped border, how to make a half circle template and tips for sewing curves together.

a wall hanging made from house and nine patch quilt blocks with a green background and black floral scalloped edge hanging on a white wall

I was very inspired by Farm and Folk’s sampler quilt with a gorgeous scalloped border, so I set out to learn how to make one myself. This tutorial by Simple Geometric Quilting was very helpful but did not go into detail on how to add seam allowance to the template. In this tutorial I walk through adding the seam allowance so you don’t need to figure it out yourself!

Sewing half circles takes practice and even after sewing the 20 half circle blocks for this wall hanging, they still didn’t end up perfect. I’m accepting the wonkiness as it gives handmade character to this piece. I used a very lightweight cotton designed for apparel and I think that made the half circles a bit harder to work with. My half circle blocks turned out much better when I used quilting cotton for my example in this tutorial.

closeup of the corner of a wall hanging made from house and nine patch quilt blocks with a green background and black floral scalloped edge

If you want to make a wall hanging like my example (or even a quilt!) head over to my review of my Hurry Home x Rue Quilt Coat where I go through all the details of the blocks needed. Then head back here for the scalloped border tutorial 🙂

I finished up this wall hanging with some scrap gingham linen for the backing, some simple hand quilting stitches, and a subtle striped linen border. I love how it turned out and the coziness it adds to this wall in my sewing room.

a finished quilted wall hanging with house quilt blocks and nine patch blocks with a scalloped floral border hanging from a branch against a white wall

showing the black and white gingham backing fabric of a quilted wall hanging with houses and nine patch blocks

Some Things You’ll Need

Card stock or regular paper
Sharp pencil
Ruler – I found this set of 3 rulers really helpful when making my template.
Paper cutting scissors
Quilting ruler
Fabric – quilting cotton works best
Fabric scissors
Rotary blade and cutting mat
Fabric marking tool
Pins – I really like these Clover Patchwork Pins for piecing.
Coordinating all purpose thread

Here’s a quick reel over on Instagram showing the process of how I made the scalloped border:

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A post shared by Bethany Lynne (@bethanylynne_makes)

Let’s get started!

Step 1: Make The Half Circle Template

To start, we need to make the half circle template pieces. It isn’t hard, but just takes a little planning up front and some measuring. These can be customized to whatever size you need.

supplies need to make a half circle template laying on a green cutting mat

I used leftover fabric from my Hurry Home Rue Quilt Coat and I wanted the half circle to be the same width as the blocks when sewn together, so that it looked like a scalloped edge when done.

Start with the finished width, the size after sewing together, that you want your half circle to be – so for me, that was 4.5″ (the unfinished size of each square is 5″). I started with a 6″ square so that I had extra space on each side for when I trim the finished half circle blocks later.

Draw a square your desired size on card stock or regular paper and then cut it out.

drawing out a square with a pencil and quilting ruler onto a white sheet of paper

the finished drawn square on a white sheet of paper with a square quilting ruler sitting next to it

Mark a line in the center of the square.

marking the center line of the 6 inch square with a quilting ruler and pencil

the finished center line drawn on the paper square with a ruler and pencil nearby

Take your desired half circle width and divide that in half. The width of my half circles is 4.5″, so half of that is 2.25″. From the center line, measure out that distance (2.25″) on either side and draw a line.

lines drawn to either side of the center line of the square cut out from white paper

At the bottom, draw a line across to mark the seam allowance (1/4″).

marking a line at the bottom of the square to mark the seam allowance

the finished marked seam allowance at the bottom of the square cut from white paper

To mark the height, measure up 2.25″ or half of the width of your half circle, starting from the seam allowance line. Note: You could experiment with this if you wanted to get a different arch shape, taller or shorter, but a more gradual arch will be easier to sew.

marking out the height of the half circle with a small ruler and pencil

Next, figure out how high you want your finished half circle block to be, and how much space you want at the top of the arch. I made mine 3.25″ high, but wish I had made mine a little bit higher. Mark that on your paper, measuring from the bottom edge and making sure to account for seam allowance.

drawing out the height of the half circle template with a quilting ruler and pencil

the finished marked lines on the half circle template

Drawing The Arch

It’s time to draw the arch! From the bottom of the center line, starting at the seam allowance line, make dots or dashed lines 2.25″ away, or the same measurement as the height of your half circle. I found a seam gauge was helpful for this.

marking the arch of the half circle moving down the side

the finished dotted lines of the right side of the arch of the half circle template

Then do the same on the other side of the arch.

making marks on the other side of the arch of the half circle template with a seam gauge and pencil

the finished dotted lines of the arch on the half circle template

Then, draw in the arch by connecting the dashed marks you made.

drawing in the arch of the half circle template by connecting the dashed lines

drawing in the last part of the arch of the half circle template by connecting the dashed lines

Make any last adjustments to the height of your template, and then cut off the extra paper along the line.

the top portion cut off the paper half circle template with scissors laying nearby

You’re almost done with the template! Next, cut out along the arch line and keep both of these pieces.

cutting out the arch from the half circle template with scissors

the finished cut half circle template pieces laying on a green cutting mat

Adding Seam Allowance

This part may seem a little redundant, but now you need to use the template you just made to make another template. It’s important though, because you’ll be adding in the seam allowance so that the pieces will fit together nicely when sewing.

Take the half circle piece you cut out and trace around it on another piece of paper.

tracing the arch of the half circle template onto another pieces of paper

the finished trace arch on another piece of paper

With a seam gauge or ruler, mark out the 1/4″ seam allowance along the outside of the half circle curve making dots or dashed marks. Draw along the dashed lines to make a curve.

marking out the seam allowance along the outside curve of the arch

continuing to mark the seam allowance along the outside of the arch curve

Cut out along the line you just drew and this is your final half circle template. I suggest labeling it so you know that this is the one with the seam allowance added.

the finished seam allowance drawn around the outside edge of the half circle

the half circle with seam allowance added cut out from the sheet of paper

Now take the other template you made (I’m calling it the “background arch” piece) and trace around it onto a piece of paper.

tracing around the arch background piece with a pencil onto another piece of paper

tracing around the background arch piece onto another piece of paper with pencil

In the same way as the half circle piece, mark the 1/4″ seam allowance along the inside of the curve with dashed lines. Draw the curve in by connecting the dashed lines.

marking the seam allowance on the background arch piece along the inside of the curve

continuing to mark the seam allowance on the background arch piece along the inside of the curve

Cut out along that line you just drew and the rest of the background arch piece. You now have your final template with seam allowance added!

cutting out the curved line along the inside of the background arch template piece

the finished half circle template pieces with seam allowance added and laying on a green cutting mat

Step 2: Trace Template And Cut From Fabric

Now it’s time to trace the templates on to your chosen fabric! Be mindful that you’re cutting with your fabric on grain to keep the pieces from stretching out.

For the background arch pieces, I find it helpful to first cut a rectangle the exact dimensions of the background arch (for me it was 6″ x 3.25″), and then cut out the arch in the middle.

cutting out a rectangle from red cotton fabric using a square quilting ruler and rotary blade

the finished cut rectangle cut out from red cotton fabric laying on a cutting mat with ruler and rotary blade next to it

You can cut out the arch with a rotary blade or you may find it easier to trace it first and then cut with fabric scissors.

tracing out the arch in the middle of the background arch template with a piece of tailors chalk

the finished drawn arch in the middle of the background arch on red cotton fabric

Next, cut out the half circle shape from your chosen fabric. I used a rotary blade but you could also trace the template onto the fabric first.

cutting out the half circle from brown floral fabric using a paper template with a rotary blade

the finished cut half circle cut from brown floral fabric using a paper template with hand resting at bottom left corner

Now you’re ready to sew!

the finished cut half circles and background arch pieces laying on a white table in rows with a hand at the bottom left corner

Step 3: Time To Sew

Now, the trickiest part is sewing these pieces together. They seem like they’re not going to fit together and you have to ease them in as you go, but it is possible!

Start by finding the middle of both the half circle and background arch pieces – I just do this by finger pressing.

finger pressing the half circle piece to find the middle

showing the mark made by finger pressing to find the middle

With right sides together, line up the center marks of the half circle and background arch pieces as shown below and place a pin.

the half circle pinned to the background arch at center marks with a hand holding the half circle in place

Then, rotate one end of the half circle piece to meet the corresponding end of the background arch piece as shown below. The straight edges should be flush with each other. Place a pin. Repeat at the other end.

bringing the ends together of the half circle and background arch piece

bringing the ends together of the half circle and background arch piece and holding them in place

Your pieces should look something like this now. See photo below.

showing the half circle pieces pinned together in three places and holding above a white table

Now, place some pins halfway between the other pins. This is where you will need to do a bit of easing in to get the curved edges lined up with each other. You can place more pins than this if you want to – it will make sewing a little easier too.

placing a pin halfway between the other pins along the curved edge of the half circle pieces

the finished pinned half circle pieces laying on a white table with a hand at bottom left corner

Before you start to sew, make sure the straight edges at the end are lined up well. This will help to make a straight edge at the bottom of the finished half circle block.

Sew around the curved edge with 1/4″ seam allowance, with the half circle piece facing up. It helps to sew a little way, sink the needle and readjust the fabric as needed, then continue sewing a bit more. I find it helpful to curve the pieces up with my fingers to help guide them together (3rd picture below).

showing the ends lined up at the ends of the half circle pieces before sewing them together

starting to sew the half circle pieces together at the sewing machine

Open it up and check out your half circle block! If you have any puckers, you can go back and unpick a little and try and ease them back together smoothly.

the finished half circle block in red and brown floral fabric holding it over a white table

Step 4: Press Seams

Before pressing the seams, make several little snips into the seam allowance making sure not to cut through your stitches. This really helps the curved seam lay flat!

clipping into the seam allowance of the half circle pieces before pressing

showing the snips in the seam allowance of the curved edge of the half circle block

Press the seam up toward the background arch piece or open. I chose to press them open so the seams were less bulky when sewing the finished blocks to each other. Try not to stretch your pieces at all, and just press without moving the ironing around.

pressing the seams open at the ironing board with a blue iron

the finished pressed open seams of the half circle block laying on an ironing board

Step 5: Trim Half Circle Blocks

Remember how I left a bit extra at each side of my template? Now it’s time to trim the blocks down to the right measurement. I’m cutting my blocks down to 5″ (the unfinished size of the blocks in my wall hanging).

The goal is to try and trim the same amount from each side, leaving about 1/4″ space (or even a scant 1/4″) on either side of the ends of the curved line.

measuring out the half circle block with a ruler before trimming and pointing out the 6" mark on the ruler

trimming down the half circle block to the desired measurement with a quilting ruler and rotary blade

I also squared up the bottom edge a little to straighten it up and double check that the height is measuring right at 3.25″.

straightening up the bottom edge of the half circle block with a quilting ruler and rotary blade

Now you have your finished half circle block!

the finished trimmed half circle block made from red and brown floral fabric laying on a cutting mat with a rotary blade next to it

three finished half circle blocks laying on a green cutting mat with a rotary blade nearby

Step 6: Sew Half Circle Blocks Together

If you’re using your half circle blocks for a scalloped border, it’s time to sew them together!

Place two half circle blocks right sides together, making sure to line up the seams at the end.

three half circles lined up next to each other on a green cutting mat with a ceramic pin dish nearby

placing two half circle blocks right sides together

Place a few pins along the edge.

two half circle blocks pinned together with three pins and holding above a green cutting mat

Sew with 1/4″ seam allowance. At the end, where the curved ends meet, try and have your stitching go right through the seam or just to the left of it. If you sew just to the left of the seams, then your scallop curves will look more seamless.