Nifty Notions: When is a ¼ inch not a ¼ inch?

Showing scant versus quarter inch seam allowance


A comparison of using scant quarter inch versus quarter inch seam allowance for patchwork by Judy Hall, a regular contributor to Into Craft.

Last month I mentioned sewing a scant ¼” seam for patchwork as opposed to a ¼” seam allowance. It has always raised so many queries as to why it is necessary and I certainly received emails privately asking for more information.


I am constantly being told by students, “But I do sew with a quarter inch foot and I do sew fairly consistent seams”. Patterns DO say to use a ¼” seam but what they are really meaning is to sew using a scant ¼” seam if machine piecing. – Why? – To achieve perfect matching of pieces and blocks.

So why do we need to sew with a scant ¼” and what is a scant ¼” seam? When sewing by machine, the nature of the top and bottom threads locking to form a straight row of stitching takes a little more space than the traditional hand stitch method. Also, seams are not pressed open as we do for dressmaking seams; they are pressed to one side so as to prevent the batting from ‘bearding’ through a sewn seam. This extra tiny fold of fabric takes up the difference between a ¼” seam and a scant ¼” seam. Only two threads worth, but this makes a huge overall difference. Hence, if piecing by machine, you should always use a scant ¼” seam allowance.

Seam allowance


The yellow thread shows a ¼” seam and the white thread shows a scant ¼” seam.


Even if you are using a Patchwork Foot or Quilting Foot, you should CHECK your seam allowance stitching line. Make adjustments if necessary to be perfect. There are several methods and tools to assist and you should refer back to last month’s editorial for some firm favourite tools to assist. Go to Nifty Notions: Sewing Straight



But first let’s run a test on your machine.


Cut two 2 ½” squares and one rectangle 2 ½” x 4 ½”.

Sew the two squares together the way you would normally sew your patchwork shapes together. The sewn piece SHOULD measure the same as the rectangle. Does it?

Cut shapes
Quarter inch seam allowance
Scant seam allowance

Here is a basic block sewn with a ¼” seam and the same block sewn with a scant ¼”. I think you can easily see that cross sections are just not going to match up with the ¼” seam.

Quarter result


Scant result
Quarter inch rows sewn

Quarter inch block sewn
Scant rows sewn
Scant sewn block
Scant sewn block back

Note the pressing of the sections and the spiralling of the centre seam.

Showing scant versus quarter inch seam allowance


Note in the right hand side block, sewn with ¼” seams, the points don’t precisely match and the side edges are irregular.

How did your test pieces measure up?… Is adjustment needed?

Check your needle position to acquire a perfect scant ¼” seam allowance by using a tool such as Westalee Design Seam Gauge as shown. Simply align the right hand edge of the sewing foot with the edge of the Seam Gauge. Lower the needle slightly and adjust the needle position until the needle fits into the slot on the Seam Gauge. Raise the needle and the presser foot to remove the Seam Gauge. (Click on images to enlarge).
Westalee Machine Guide

Once set, the Westalee Machine Guide will assist in sewing consistent seams. Place the adhesive side of the Sewing Machine Guide against the right hand side of the presser foot as shown.

Westalee Machine Guide sewing

Note that when sewing small sections such as in patchwork piecing, it is preferable to use a small piece of scrap fabric as a leader so no bunching up of stitches occurs at the commencement of a patchwork seam.

Qtools Sewing Edge in use

Other helpful tools are The Angler2 by Pam Bono Designs, the fast2sew Ultimate Seam Guide from C & T Publishing and various adhesive strips to place down on the sewing area. The best of which is the Qtools Sewing Edge shown in last month’s editorial.

All better than the elastic band around the freearm of your machine, sticky tape or using texta or nail polish to mark the guideline!…Hmmm.

Off to the sewing room to sew some patchwork blocks with everything perfectly aligned up like you’ve never sewn before because you are now sewing with a scant ¼” seam!

Products are available from good haberdashery retail outlets or from the Punch with Judy stand at the Craft & Quilt Fairs and Craft and Sewing Shows. Or visit


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