What Are Hem Types and Why Do They Matter?
A hem is the finished edge of a garment, such as the bottom of a t-shirt, the end of a sleeve or the leg opening of a pair of trousers. The way that edge is folded, stitched or bound is the hem type. Seams are where two pieces of fabric join, and stitches are the thread patterns that hold both together. Hem types, seam types and stitch types are three linked choices, and each affects appearance, strength, stretch and cost.
For a clothing brand, hem types matter for three reasons. They are visible, because customers notice a neat or wavy hem straight away. They are functional, because a hem on a stretch knit has to stretch with the fabric without breaking. And they are commercial, because different finishes need different machines and different amounts of operator time, which feeds into the price. A factory will choose a default if your tech pack is silent, so it is better to choose deliberately.
The sections below cover the common hem finishes, then seams and stitches, then how to choose between them. For the document where you record the decision, see our tech pack guide.
Common Hem Types in Clothing
Hem finishes fall into a few families. Some fold the raw edge inside, some finish the raw edge and fold once, some leave the edge raw on purpose, and some wrap the edge in a separate strip. The table below sets them out, along with the garments they usually suit and the machine typically used.
Hem types compared
| Hem type | How it is made | Typical garments | Typical machine |
|---|---|---|---|
| Single-turn hem | Edge is overlocked, then folded once and stitched | Woven shirts, casual trousers, light jackets | Overlock, then lockstitch |
| Double-turn hem | Edge is folded twice so the raw edge is enclosed | Woven shirts, skirts, trousers, cotton casualwear | Lockstitch |
| Coverstitch hem | Edge is folded once and stitched with parallel rows that stretch | T-shirts, hoodies, joggers, sleeves and cuffs of knits | Coverstitch machine |
| Blind hem | Edge is stitched so the thread is almost invisible on the outside | Tailored trousers, skirts, dresses, jackets | Blind-stitch machine |
| Raw hem | Edge is cut and left unfinished, sometimes with a wash to fray | Some denim and jersey, where the look is intended | None, or a washing process |
| Rolled hem | Very narrow edge rolled and stitched or overlocked | Lightweight wovens, scarves, fine fabrics | Rolled-hem foot or overlock |
| Bound hem | Edge is wrapped in a separate strip of fabric or tape | Jackets, unlined garments, decorative finishes | Binder attachment on lockstitch or coverstitch |
General guide. Names vary between factories, so confirm the construction with a drawing or reference garment.
It helps to know the vocabulary that sits behind the table. A turn is one fold of the fabric edge, so single-turn and double-turn describe how many folds hide or expose the raw edge. Finished depth is the visible width of the hem after stitching, and it is not the same as the allowance, which is the extra fabric needed to make it. Mixing those two measurements up is a frequent source of garments that come back shorter than expected.
Two of these, the coverstitch hem and the double-turn hem, account for most of the hems you see on everyday casualwear. The coverstitch suits knits because its looper thread on the underside stretches, while the double-turn hem suits stable wovens where a neat enclosed edge is wanted.
Seam Types: How Pieces Are Joined
Seams do more than join fabric. They carry load, give shape and show on the outside or inside. A plain seam is the most basic, with two pieces stitched together right sides facing. Everything else is a variation on how the raw edges are enclosed or reinforced.
Main seam types
| Seam type | Description | Strength and finish | Typical use |
|---|---|---|---|
| Plain seam | Two layers stitched, seam allowances pressed open or to one side | Simple; raw edges need finishing | Lined garments, tailored pieces |
| Overlock (serged) seam | Edges trimmed and wrapped with looped thread | Neat, fast and stretchy | T-shirts, hoodies, most knitwear |
| French seam | Seam sewn twice so the raw edge is enclosed inside | Clean inside; best on light fabric | Delicate shirts and dresses |
| Flat-felled seam | Seam allowances folded and stitched flat | Very strong; clean on both sides | Jeans, workwear and shirts |
| Bound seam | Raw edge wrapped in tape or bias binding | Tidy inside; adds bulk and cost | Unlined jackets |
| Lapped seam | One edge laid over the other and stitched | Flat and strong | Denim yokes, some jackets |
General descriptions. The right seam depends on the fabric, the garment and the target price.
A flat-felled seam is the classic construction for denim because it is strong and has no exposed raw edge. We look at how those seams are stitched in our guide to jeans stitching. On a t-shirt, by contrast, a four-thread overlock seam is usual, because it trims, joins and finishes the edge in one pass with built-in stretch.
Stitch Types: Lockstitch, Chain Stitch, Coverstitch and Overlock
Stitches are the thread patterns that form the seam or hem, and the stitch type is what decides how much a seam can stretch and how it holds up. Industry stitch classes are catalogued in the ISO 4915 standard, which groups them by how the threads interlock. Factories often talk in terms of the class number, so it is worth knowing the main four families.
Main stitch families
| Stitch family | How it behaves | Where it is used |
|---|---|---|
| Lockstitch (class 301) | Needle thread and bobbin thread lock in the fabric; same on both sides; limited stretch | Woven seams, topstitching, hems on stable fabric |
| Chain stitch (class 401) | Looper thread forms a chain underneath; some give, can unravel if broken | Jeans hems and waistband seams |
| Overlock (classes 504, 514) | Looped threads wrap the fabric edge; flexible | Knit seams and edge finishing |
| Coverstitch (classes 406, 602) | Two or more needle rows with looper cover thread; stretchy and flat | Knit hems, cuffs and neck bands |
Class numbers follow the ISO 4915 stitch classification. Check the exact class with your factory.
Choosing the stitch is not decoration. A lockstitch hem on a stretch t-shirt can pop its threads the first time the garment is pulled over a head, because the stitch cannot stretch with the fabric. The tech pack should therefore specify both the hem type and the stitch type for each edge.
Which Hem and Seam Finish for Which Fabric?
The fabric determines the finish more than the designer's preference does. Stretch knits need stitches that stretch. Heavy denim needs a strong seam and a hem that can be folded through thick layers. Lightweight woven fabrics need narrow, neat hems that do not pull the cloth. The table matches the common fabric groups to their usual finishes.
Choosing a finish by fabric
| Fabric group | Usual hem types | Usual seam type | Notes |
|---|---|---|---|
| Jersey and knit (t-shirts, hoodies) | Coverstitch hem, sometimes a raw or rolled edge | Four-thread overlock | Avoid plain lockstitch on stretch areas |
| Fleece and French terry | Coverstitch hem; ribbed cuffs and hem bands | Overlock | Bulky fabric; check seam bulk at joins |
| Denim | Single-turn or double-turn hem; chain stitch or lockstitch; raw hem for a deliberate look | Flat-felled and overlock | Wash shrinkage affects the hem; allow for it |
| Woven shirting and casual cottons | Narrow double-turn or rolled hem | Plain, French or overlock | Light fabrics need small stitches and narrow hems |
| Tailored trousers and skirts | Blind hem or double-turn hem | Plain seam, pressed open | Hem depth affects drape and hang |
| Outerwear and jackets | Double-turn, bound or faced hem | Plain, lapped or bound | Thicker layers need longer stitch length |
Common starting points only. Samples will confirm what works for your exact fabric.
Fabric weight changes the answer inside each row. A light cotton jersey can take a narrow coverstitch hem, while a heavy fleece may need a wider hem allowance to lie flat. For help matching structures to uses, see our jersey fabric guide.
Hem Allowance: How Much Fabric Goes Into the Hem?
Hem allowance is the extra length added to a pattern piece so that it can be folded up to create the hem. A pattern cutter adds it beyond the finished length, so a garment ends up at the length you specified once the hem is turned. The right amount depends on the fabric, the hem type and the garment, and it needs to be consistent across sizes so that the finished measurements do not drift.
Typical hem allowance by garment
Approximate fabric turned up, in centimetres
Typical ranges only, which vary by product, fabric weight and factory. Always check against your pattern cutter and tech pack.
Allow for washing as well. If a fabric shrinks in length, a hem that looked right on the sample may be shorter after a wash. Garment washing or pre-shrinking, and testing, reduce the risk. Our guide to sewing patterns and industrial garment patterns explains how allowances are built into production patterns.
How Hem and Seam Finishes Compare
Different finishes make different trade-offs between strength, stretch, bulk and cost. The ratings below summarise how the most common choices typically compare. They are indicative: actual results depend on the fabric, the operator and the machine setup.
Comparing common hem finishes
1 dot = low, 5 dots = high
| Coverstitch hem | Double-turn hem | Blind hem | Raw hem | |
|---|---|---|---|---|
| Durability | ●●●●● | ●●●●● | ●●●●● | ●●●●● |
| Stretch recovery | ●●●●● | ●●●●● | ●●●●● | ●●●●● |
| Low bulk | ●●●●● | ●●●●● | ●●●●● | ●●●●● |
| Neat inside | ●●●●● | ●●●●● | ●●●●● | ●●●●● |
| Low production cost | ●●●●● | ●●●●● | ●●●●● | ●●●●● |
Indicative ratings for typical use, not measured results.
A raw hem looks simple but is not necessarily the cheapest option, because it depends on the fabric not fraying badly and on the wash. The ratings show why the coverstitch hem dominates knitwear and casualwear: it is the only common finish that combines durability and stretch.
How to Specify Hems and Seams in a Tech Pack
A good specification names the hem type, the stitch type and the finished hem depth for every edge, and gives a drawing or photo. If the factory has to guess, it will use its default, which may differ from the reference garment you had in mind.
Specifying a hem in six steps
- 1Name the hem typeFor example: coverstitch hem on body and sleeve.
- 2Give the finished depthState the finished hem depth in centimetres or millimetres.
- 3Set the stitch typeSpecify lockstitch, chain stitch or coverstitch, and stitches per inch if needed.
- 4Match thread and colourState thread type and colour, including top and bottom threads.
- 5Add a detail drawingDraw a cross-section or attach a photo of the reference.
- 6Approve on the sampleCheck the hem for flatness, stretch and depth on the first sample.
Stitches per inch (SPI) is a standard measure of stitch density. Your factory can advise on a suitable range.
If you are copying a garment you already own, photograph the hem from the outside and inside, and measure the depth. It speeds up the discussion with the factory and helps your technical flat to be exact.
Common Hem Faults and How to Fix Them
Hem problems are rarely about the operator alone. The same fault can come from fabric, machine and pattern together, so it pays to look at all three before deciding who is responsible. Good factories test a hem on the actual production fabric before the bulk run starts, and that test is where most of these faults are caught and corrected.
Most hem problems come from a mismatch between fabric, stitch and machine setup rather than poor sewing. Recognising the symptom helps you describe the fix to the factory.
Typical hem faults
| Fault | Likely cause | Typical fix |
|---|---|---|
| Wavy or rippled hem | Stitch tension too tight, fabric stretched while sewing, or wrong stitch for knits | Adjust tension and feed; use a coverstitch with differential feed |
| Twisted side seams | Off-grain cutting or uneven knit | Check grain in cutting; use a stable fabric; pre-shrink |
| Uneven hem depth | Inconsistent folding or no guide | Use a folder or guide; mark the hem line |
| Popped stitches | Non-stretch stitch used on a knit | Change to coverstitch or stretch stitch |
| Puckered hem on woven | Stitch too long or tight for a light fabric | Shorten stitch, reduce tension, use a finer needle |
| Hem shows through to the outside | Fabric too thin for hem depth or pressing mark | Reduce hem depth or use a blind hem and interlining |
Quality inspection should look for each of these at the sample and at the production stage. Our guide to AQL inspection explains how defects are counted and how acceptance levels work.
Checklist: Specifying Hems, Seams and Stitches
Before you send your tech pack, run through the list once more. A complete specification leads to a better sample and fewer rounds of comments.
Hems and seams checklist
- Every garment edge has a named hem type.
- Finished hem depth is stated in millimetres or centimetres.
- Stitch type is matched to the fabric: stretch stitches for knits.
- Seam type is chosen for strength and finish, such as flat-felled for denim.
- Thread type and colour are specified for visible stitching.
- The allowance for washing shrinkage has been considered.
- A reference photo or cross-section drawing is attached.
Keep the list with the tech pack so the same questions are asked for every style you develop. Over time, it becomes your own standard construction sheet.
How Ruhrose Handles Hems and Construction
Ruhrose develops hoodies, jersey, denim and woven casualwear for UK buyers, with production in Bangladesh, so the hems and seams in this guide are everyday work: coverstitch hems and ribbed bands on knits, flat-felled seams and chain-stitch or lockstitch hems on denim, and double-turn hems on woven casualwear. We confirm construction against your reference or tech pack at sample stage, before bulk. For the wider picture of how a garment moves through the factory, read our garment production process step by step.