Manufacturer · Fashion & Home Accessories
How much elastic to cut for a waistband depends on how much the particular elastic stretches. As a guide, waistband elastic is usually about 8–15% shorter than the waist measurement, plus an allowance for joining the ends. For cuffs and leg openings the reduction is similar, and for necklines it is smaller. The exact length is determined with a short stretch test and a trial.
Why there is no single number
Two elastics of the same width can behave completely differently. A soft knitted elastic for pyjamas stretches easily and almost doubles, while a dense woven elastic for work trousers is firm and stretches less. If you cut both with the same reduction, the first will be too loose and the second too tight. That is why professionals do not measure "by eye" but determine the ratio for each elastic article separately.
How much elastic to cut – the stretch test
- Cut a piece of elastic exactly 10 cm long, marked with two lines.
- Stretch it to a position where it is comfortably taut, but not at its limit.
- Measure the length between the lines. If it is 17 cm, the elastic has about 70% comfortable stretch.
- Stretch it fully and measure the maximum stretch.
- Record both values for this article.
Once sewn in, the elastic should work within its comfortable stretch zone, and its maximum must be enough for the garment to pass over the widest part of the body when dressing – hips, foot, hand or head.
Guide table by area
| Area | Reduction relative to the circumference | Check |
|---|---|---|
| Waistband of trousers, skirt, joggers | about 8–15% | Passes over the hips |
| Waistband of pyjamas, loungewear | about 5–10% | Does not press when lying down |
| Sleeve cuff | about 10–15% | Passes over the hand |
| Leg opening of shorts, underwear | about 10–20% | Does not dig in when sitting |
| Neckline and armhole | about 3–8% | Lies flat, does not gather |
| Fitted sheet elastic | according to mattress depth | Holds the corners |
The percentages are a starting point for the trial, not a rule. Woven and knitted elastic in the same area will require different reductions. The types of elastic for each area are described in the elastics category.
Calculation example
Waist 80 cm, soft knitted elastic 30 mm:
- reduction of about 10%: 80 × 0.90 = 72 cm;
- allowance for overlapping the ends: about 2 cm;
- cutting length: about 74 cm.
Then check whether 72 cm of elastic, comfortably stretched, reaches the hip measurement, for example 100 cm. If the comfortable stretch of the elastic is 70%, 72 cm stretches to about 122 cm – enough. If the elastic is firm and stretches only 30%, 72 cm barely reaches about 94 cm and the trousers will not pass over the hips – you need a softer elastic or a smaller reduction.
How the width of the elastic matters
A wide elastic exerts more force at the same reduction, because it has more elastic threads. So if you switch from 25 to 40 mm elastic with the same reduction, the waistband will be tighter. With a wide waistband elastic, the reduction is usually decreased. You will find firm elastic for trouser and skirt waistbands in the woven elastic category.
Elastic in a channel or sewn directly
With elastic in a channel, the fabric gathers freely around the elastic and the length of the elastic alone determines the circumference. When sewn directly, the elastic is stretched while sewing and then contracts, and the seam takes away a little of its elasticity. That is why, for direct sewing, the elastic is often cut slightly shorter or a softer one is chosen. Test on a sample with the real seam – overlock, coverstitch or zigzag.
Grading by size
In series production, the elastic length is specified for each size in the tech pack. It is not correct to increase the elastic by the same amount between sizes if the circumference increases by a different step. Calculate the reduction as a percentage and apply it to the circumference of each size. Check at least the smallest and the largest size on trial garments.
Common mistakes
- The same reduction for all types of elastic.
- Measuring the elastic in a slightly stretched state – it gets cut too long.
- Forgetting the allowance for joining the ends.
- Testing new elastic rather than after washing – some elastics shrink or relax slightly after the first wash.
- Not checking whether the garment passes over the hips or the hand.
Children and soft knitted elastic
For children's clothing, prefer a smaller reduction and a soft knitted elastic. The child should be able to put the garment on and take it off alone, and the elastic must not leave marks on the skin.
Elastic after washing
Before fixing the lengths in the tech pack, wash a sample of the elastic or the whole trial garment at the temperature on the care label. Some elastics shrink slightly in length, others relax a little after the first wash. If the difference is visible, adjust the cutting length. The test takes a day but saves complaints for a whole production run. Record the result together with the article number – the next time you order the same elastic you will not need to repeat the calculations from scratch.
Elastics from Polkom
Polkom is a Bulgarian manufacturer of accessories for fashion, furniture, footwear and bags, based in Sofia. We deliver knitted, woven and round elastics in various widths and degrees of firmness, with samples for testing and delivery across the EU. Minimum quantities depend on the article. Send us the style and the fabric via the contact page – we will help you choose the elastic and determine the length.
