What Can and Cannot Be Altered Easily
A realistic guide to which garments suit a beginner alteration and which ones are better left to a professional.
What you will learn
- Judging a garment before altering
- Measuring available seam allowance
- Spotting alteration marks
Good first alterations
Simple, unlined garments made of woven fabric are the best place to start. Shortening a straight hem on trousers, a skirt or a plain dress is easy and forgiving. Taking in side seams on a simple, unlined garment is also reasonable, because the seams are straight and nothing complicated lies inside them.
Harder garments
- Structured garments such as blazers, coats and tailored dresses contain interfacing, canvas, padding and boning. Changing the shape disturbs all of these layers.
- Lined clothing has a second garment inside. Any change to the outer layer has to be matched in the lining, and often means opening seams that are hard to reach.
- Complex waistbands, including curved waistbands, those with hooks and bars, and ones with stiff interfacing, are fiddly to take apart and rebuild.
- Tailoring such as set-in sleeves with a sleeve head, bound buttonholes, working cuff buttons and shaped shoulders requires professional skill and tools.
- Leather, suede and heavily embellished fabric show every needle hole and cannot be unpicked cleanly.
Check how much fabric you have
Before any change that makes a garment bigger or longer, find out how much seam allowance or hem allowance is available. Turn the garment inside out and measure the fabric between the stitching and the raw edge.
Many ready-made garments have a seam allowance of only 3/8 in (10 mm), and some have 1/4 in (6 mm) or less. Letting out a seam gains twice the allowance you release, but about 1/4 in (6 mm) must stay at the raw edge. A 3/8 in (10 mm) allowance therefore releases only 1/8 in (3 mm) and gains about 1/4 in (6 mm) per seam. Hems on ready-made trousers are often 1 to 1 1/2 in (2.5 to 4 cm).
Fraying is the second limit. If a raw edge frays heavily, a narrow allowance may disappear as you handle it.
Old stitch lines and fade marks
When you open a seam or unpick a hem, the old stitch holes and fold lines can remain visible. On soft or loosely woven fabric, such as wool, they often disappear with steaming. On dark, dense or heavily pressed fabric, denim, cotton twill and shiny fabric they are often permanent.
Fading is the other mark. A hem that has been worn and washed has a crease where the fabric folded, and the colour is lighter along that line. If you lengthen the garment, the old fold line may show as a visible ridge or lighter line. Test a small area by steaming it before you commit.
Be honest about these limits. If an old line still shows after pressing and steaming, plan the new hem to cover it, or leave the hem alone.
Tips for a neat result
- Press the old crease with a damp cloth and see how much it fades before unpicking a whole hem.
- Start with a garment you can afford to ruin.
Common mistakes and fixes
I let out the seam and the fabric frayed away.
The allowance was too narrow. Check the amount before unpicking anything, and stop if there is less than 3/8 in (10 mm) to work with.
The old hem line is still visible after I lengthened the garment.
The fold set into the fabric. Try steam and a pressing cloth first, then cover the line with trim or choose a new hem depth that hides it.
Check your result
- You know how much seam or hem allowance your garment has before you choose a change.
- You can decide whether the project is suitable for you or needs a professional.