How to Sew a scant 1/4 Inch seam
Most of the time sewing a 1/4 inch seam allowance is totally fine. It may mean your completed blocks may be a little smaller than the pattern’s stated dimension and therefore the finished quilt will be slightly smaller. As long as your seam allowance is consistent and your blocks are all the same finished size it doesn’t matter!
But there are times when sewing a scant 1/4 inch seam really does matter!
For example:
The Cosmic Cactus pillow has a lot of seams in a small area, plus half-square triangle and flying geese points to match up. Without a scant 1/4 inch seam you will struggle to match the seams and points.
When testing the Urban Crossways pillow pattern I discovered these blocks didn’t match up without using a scant 1/4 inch seam.
Read on to discover what a scant 1/4 inch seam is; when a scant 1/4 inch seam matters; and how to sew a perfect scant 1/4 inch seam in Two Easy Steps!
Disclaimer: You should always follow the guidance outlined in the pattern and use a scant 1/4 inch seam when a pattern asks for it.
What exactly is a scant 1/4 inch seam?
A scant 1/4 inch seam requires you to sew just under 1/4 inch, which is typically a thread or two with your normal 1/4 inch seam. When pressing your fabric either open or to the side, you lose a little bit of fabric to the thread width and fold after pressing. A scant 1/4 inch seam will account for the loss in fabric and allow you to maintain your block size.
Example: The difference between an exact 1/4 inch and a scant 1/4 inch seam.
When a scant 1/4 inch seam matters
If your pattern calls for a 1/4 inch seam then definitely follow the guidance in the pattern. There’s a very good reason the designer has suggested this. Some reasons may be:
Typically blocks with many seams are more likely to require a scant 1/4 inch seam.
The pressing direction can make a difference, with open seams generally being flatter and more precise. When you’re pressing to the side there’s more chance of creating a larger fold around the seam. I generally press my seam open and find it achieves better results. But this is a personal preference.
You may also need to adjust your seam allowance to account for:
Fabric weight - Depending on the fabric you are sewing with, you may need to adjust your seam allowance for a thicker fabric. For instance, you may notice a difference with your seam allowance when sewing with an Art Gallery and Kona fabrics.
Thread weight - The thickness of your thread can make a difference. A 50 weight thread is recommended for piecing, with a 40 weight thread or thicker will have an impact on the accuracy of your seam allowance.
How to Achieve a perfect scant 1/4 inch seam (in two easy steps)
1. Check your sewing machine feet and decide which of these options work best for you:
Option 1
Check if you have a scant 1/4 inch foot. I didn’t even know they existed, but it’s possible your sewing machine might have a sewing machine foot that can sew a scant 1/4 inch seam.
GUESS WHAT? While writing this blog I discovered I had a scant 1/4 inch foot. The HP Plate and HP foot were one of a number of accessories that came with my Janome Memory Craft 9450QCP sewing machine. All I had to do was attach the HP Plate and HP Foot, then when sewing match the edge of the foot against the edge of the fabric and I had a scant 1/4 inch seam allowance! Find out more about about the HP Plate and HP foot (which has other cool features) and check if it’s compatible with your Janome sewing machine.
I have a HP Foot for my Janome sewing machine that sews a scant 1/4 inch.
Option 2
Move the needle position if your sewing machine allows.
With 1/4 inch seam foot. Attach foot and then using your sewing machine settings adjust the needle to the right and then test your seam width.
With any sewing machine foot: With a ruler and using the edge of your sewing machine foot as your guide, move your needle position to the right until you find the optimal position to sew a scant 1/4 inch seam. Then test your seam width.
Option 3
Use tape or a guide on your sewing machine.
This is a reliable method that can be used on any sewing machine, especially if you can’t adjust the needle position. Tape is cheap and easily available, but you may find purchasing a guide is better suited to you, especially if you are an avid quilter and going to be sewing a lot of quilts.
Simply measure out a 1/4 inch and then make a small adjustment to make the seam smaller. Then test your seam width.
2. Test and check your seam width.
To test you are sewing a perfect scant 1/4 inch seam:
Cut 3 x 1.5 inch wide strips of fabric.
Sew them together using a scant 1/4 inch seam.
Press seams open. Check the centre strip measures exactly 1 inch wide. Well done, you have now achieved a perfect scant 1/4 inch seam.
Centre strip not 1 inch! Make adjustments and repeat these steps until you achieve a perfect scant 1/4 inch seam.
Check the centre strip measure exactly 1 inch wide. Well done, you have now achieved a perfect scant 1/4 inch seam!
