The seam allowance of a sewing pattern is simply the extra room around the stitching lines. This lets you know how far in from the cut raw edge you will be sewing your seam. Using the wrong seam allowance will mean your clothing may be too big or too small so it is important to learn how to add seam allowance correctly.
It is important to note that different designers will have different rules so it is always important to check carefully before you start cutting.
My patterns all include the seam allowance which means you don’t need to alter the pattern in any way. You just cut around the pattern and start sewing.
The actual seam allowance will vary depending on the project and will be specified in the notes.
As a general rule My Childhood Treasures’ (MCT) sewing patterns have the following seam allowances included. (There are always some exceptions so please check your pattern before you start.)
- Wovens: 1/2 inch (12mm)
- Knits : 3/8 inch (1cm)
- Leotards: 1/4 inch (12mm)
- Doll’s clothing: 1/4 inch (6mm)
- Clutches/Bags: 3/8 inch (1cm)
It is common for European designers to add NO seam allowance to their patterns. If you have a pattern from another designer that needs a seam allowance added here is what you do.
HOW TO ADD SEAM ALLOWANCE
You can add your seam allowances directly onto your fabric or onto paper first.
Step 1: Place your pattern pieces on your fabric or paper with enough room between them to add the seam allowances. Decide what seam allowance you would like to add. If you are a beginner and not sure what to add, then refer to my rules above.
Step 2: Using a chalk or removable pen, add the seam allowance all around the pattern using your ruler. If you have a regular ruler just make a series of dashes and join them up. It can be a bit faster if you use a quilting ruler as you can draw longer lines at once. For curved parts, make a series of small dashes and join them up. You can use a curved ruler or French curve at the end to smooth out the curve.
Seam Allowance on the Fold
Just to trick you up there are a couple of exceptions. Do not add seam allowance on a seam which is placed on the fold of the fabric.
How to Add Seam Allowance to Hems
Where you have a hem you may need to add extra seam allowance. Your pattern instructions should specify how much. If it doesn’t then try adding 3/4 inch (2cm) any hems. This allows you to turn the hem twice. Once at 1/4 inch (6mm) then again at 1/2 inch(12mm).
If you need to add seam allowance to an angled piece such as a sleeve, continuing at the same angle means the hem will become too narrow when folded. You will need to angle the hem outwards as shown in the diagram.
PRODUCT HACK: HOW TO ADD SEAM ALLOWANCE FAST
Add seam allowances by sticking 2 pencils together. Use one to mark and the other to guide around the edge.
STITCHING THE CORRECT SEAM ALLOWANCE
Once you have cut your fabric out you will need to stitch it together using the correct seam allowances.
If you look at the plate of your sewing machine you will see that there are different numbers and lines marked. These are the seam allowance guides.
When the needle is in its center position you should align the raw edges of your fabric with the appropriate seam allowance guide. Start stitching maintaining the same distance.
BEGINNERS TIP FOR SEWING WITH SEAM ALLOWANCES:
New sewers may want to put a piece of colored tape or even rubber bands along the seam guide they will be using.
READ MORE FOR SEWING FOR BEGINNERS