Cambridge – Adjustable Waist Pants


Blogger: Christine Hanes

Cambridge – Adjustable Waist Pants

I love being able to make pants that fit my daughter just right, and sometimes that just right fit changes from day to day. To be able to customize the fit, we love adjustable waist pants so they are always comfortable for her and they get extended wear. Today in this blog, I am going to show you how to make the Cambridge pants with an adjustable waist. 

For this hack, you will need 1” (2.54 cm) buttonhole elastic and buttons that fit the buttonholes and within the seam allowance. 18mm buttons work perfectly for 1” (2.54 cm) elastic. 

Add ½ inch length to the waistband pieces, so that the edges of the seam are a little further back from the opening if serged/zig zag finished, or so they can be folded over to have no raw edges. 

Place the front waistband wrong side up. Find the center of one short side of the front waistband piece. Measure down 1/8” (0.3 cm) from the center and mark it with a ¾” (2 cm) horizontal line. Measure up ½” (1.3 cm) from the bottom, raw edge of the waistband and mark it with a ¾” (2 cm) horizontal line. Draw a vertical line ¾” (2 cm) in from the outer raw edge connecting the top mark to the top of the waistband and the bottom mark to the bottom of the waistband. Repeat on the other short side of the front waistband piece. 


Place the back waistband right side up. Place the front waistband on top, right sides together. Align one short end. Sew directly on top of the vertically marked 3/4" (2 cm) seam allowance line, leaving a gap between the two horizontal markings. Backstitch several times to lock the stitches as this seam will endure a lot of stress. 


Press the seams open.


Finish the side, raw edges with a zig zag stitch or serger.

Otherwise, fold the side, raw edges 1/4" (0.6 cm) wrong sides together. Please note that the folding method will be slightly bulkier. Repeat all steps on the other side. Edgestitch the seam allowance down.


With wrong sides together, fold the waistband in half lengthwise. Press to create a memory crease. 

There are two methods for attaching the button to the waistband piece.  

*The traditional method has the button on the inside of the pants, on the right side of the waistband fabric. This is what I have most commonly found in store bought pants and the elastic is simple to adjust. 

*Measure over 1" (2.5 cm) from the opening/slit created in the waistband, towards the front of the waistband, and make a mark.

This is where the button will be placed. Make sure the button fits the buttonhole elastic and the edges are at least 5/8” (1.6 cm) above the raw edge and 1/4" (0.6 cm) below the top fold. 

 Sew the button on. Repeat on the other side.


**An alternative method places the button on the wrong side of the waistband piece, so it will end up sandwiched inside the waistband fabric pieces. It is a little fussier to adjust because it is in between the two fabric pieces, but conceals the button and elastic, which may be more comfortable for kids with sensory sensitivities.  

**Measure over 1/4” (0.6cm) from the opening/slit created in the waistband, towards the back of the waistband, and make a mark.

This is where the edge of the button should sit, so it is close to the opening/slit. Make sure the button fits the buttonhole elastic and the edges are at least 5/8” (1.6 cm) above the raw edge and ¼” (0.6cm) below the top fold. (Photo to be added) Sew the button on. Repeat on the other side. 


Fold the bottom of the waistband up 1/2" (1.3 cm) wrong sides together and press. (The same side the buttons were just sewn on). 


Follow the pattern as written to attach the waistband to the pants. Slide the waistband over the pants, right sides together. Align the side seams of the waistband with the side seams on the pants, making sure the front waistband (with the buttons) is aligned with the front side of the pants.


Sew to attach with a 1/2" (1.3 cm) seam allowance. 

Press the seam allowance up. 

Re-press the memory crease and topstitch the waistband down. When topstitching the waistband down, sew around the entire waistband instead of only sewing the back. 

Cut the buttonhole elastic 4 inches longer than the pattern calls for. Draw a line two inches from each edge. 

You can finish the edges of the elastic with a zig zag stitch or serger, or fold the edges over ¼” (0.6 cm), then another ¼” (0.6 cm) to prevent unraveling (but this does add some bulk). Thread the elastic through the openings created inside the waistband seam. 

Use the lines drawn two inches from each edge as a guide to pull the elastic through evenly. 

Find the back center of the waistband, then sew a line vertically through the waistband & elastic to secure the elastic in place. 

The buttonhole elastic can now be adjusted to fit comfortably. 



The excess elastic can be pushed back through the waistband seam opening, for a more comfortable fit when the pants are worn. 


**If adding the alternative button placement, the elastic can be pushed through the opening/slit toward the front waistband. 

Follow the pattern instructions to finish the pants, by hemming the bottoms. Then admire your handiwork! 




More Posts