Accurate Quarter Inch Seams

Tags: how-to, quilting lesson

It is important to be able to sew an accurate 1/4" seam. For many machines you can purchase a machine foot that is exactly 1/4" from the needle to the side of the foot. They are a very useful tool. I have found that many machines, especially older ones, have a foot that is an exact 1/4" so please check and measure the feet that are with your machine before you purchase one.

use a quarter inch foot on your sewing machin to make a quarter inch seam
Quarter inch foot makes it easy to sew an accurate quarter inch seam.
It measures exactly 1/4" from needle to edge of foot

Let us look at some ways of making your accurate seam without a 1/4" foot

If you do not have one of these or cannot obtain one for your machine, you need to measure and mark out 1/4" from your needle so that your seam is accurate. Sometimes you can adjust the needle position and use the edge of another presser foot.

adjust needle position to make a quarter inch seam
The needle has been moved right. The green line indicates a
measurement of 1/4" between needle and edge of presser foot

Remember, this has to be exact for your piecing to work accurately.

There are two other ways to make an accurate seam. Measure 1/4" from the needle then either, mark the distance on the top of your presser foot with a permanent marker OR stick a piece of tape at this distance onto the bed of your machine. The latter method is not so good as sometimes the fabric will cover the tape. Only use this as a last choice as you will have difficulty when attaching the narrow border in this design.

mark sewing machine foot to make a quarter inch seam
Use a permanent marker to mark top of presser foot,
1/4" from needle 
use a fine tip marker

use tape to mark a quarter inch seam
Stick tape to your sewing machine bed, 1/4" from needle.
The green line indicates 1/4" from needle to side of tape

Make a sample test by sewing together your four 2" squares of scrap fabric in a row using accurate 1/4" seams. Press the seams to one side and measure through all squares across strip from the right side. It should measure 6 1/2" if you have done this accurately.

piece squares together for an accuracy test
Four 2" squares sewn together with 1/2" seams gives
a measurement of 6" plus 1/2" seam allowance, totaling 6 1/2"

If your strip is not accurate, you may need to adjust your 1/4" measurement, but first check you have pressed the strip correctly. Pressing should be done from the right side of the block. For more details on pressing see our Pressing Lesson. If your pressing is correct, then make the adjustment to your seam and try again.

Why is it important to sew an accurate 1/4" seam? For correct piecing this is important to avoid having trouble joining adjacent seams and matching points. Imagine if you can join eight 2" squares together correctly the length of the strip would equal 12 1/2". If your seams are all out by just 1/16", your piece would be 1" short of the required measurement. Now, how difficult it would be to attach this to a 12 1/2" strip?

Tip: Do not be fooled if you hear someone say "sew a scant 1/4" seam". Many quilters swear by this and say it is the most accurate way to making a block. In essence, what they mean is a scant 1/4" seam ALLOWANCE which is the result of an accurate 1/4" seam. An accurate 1/4" seam is measured from the right side of your block as you did in the test above, this will likely leave a scant 1/4" seam allowance.

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