Weft knits vs warp knits: single jersey, rib, interlock and other common structures

Learning to tell single jersey, rib and interlock apart by looking at the fabric, not by guessing

This page is for anyone who reads a fabric swatch, a tech pack, or a mill's specification and needs to know exactly what knit structure the fabric is: a merchandiser, a buyer, a quality controller, a mill employee, or a new entrant to the trade. Lesson 2.1 explained what knitting is; this lesson does not require it, though it helps.

A merchandiser who cannot tell single jersey from rib from interlock cannot check whether a swatch matches a tech pack, cannot explain to a buyer why one fabric curls at a raw edge and another does not, and cannot stop a factory from cutting the wrong fabric for a design that actually needed strong widthwise stretch, not flat stability. Order A's own 180 GSM T-shirt fabric is a single jersey. This lesson teaches you to recognise that structure, and the two others you will meet most often on a knitwear order, by their loop pattern, their face, and how they behave.

What you need, and what this lesson does not cover

You need: to know that a knitted fabric is built from loops, not from two crossing sets of yarn (lesson 2.1). No other lesson is required.

By the end of this lesson you can:

• describe single jersey's loop pattern and say why it curls at a raw edge;
• describe rib's loop pattern and say why it stretches widthwise without curling;
• describe interlock's loop pattern and say why it is thicker and more stable than single jersey;
• identify Order A's own 180 GSM fabric as a single jersey;
• use a two-step check to tell single jersey, rib and interlock apart from a swatch or a description alone.

Not covered here: how gauge, stitch length and GSM describe a knit structure precisely (lesson 2.3), why knitted fabrics stretch and how that affects pattern-making (lesson 2.4), and choosing a structure for a new product brief (lesson 2.5).

Words you will meet in this lesson

Single jersey, rib and interlock are told apart by how many needle beds form them and how their two faces compare

Single jersey uses one needle bed, forming loops in one direction only. This is the lightest and simplest weft-knit structure: it has a distinct flat (knit) face on one side and a looped (purl) face on the other, and it tends to curl at raw edges because nothing balances the pull of the loops on each side. Rib alternates knit and purl columns using two needle beds. This balances the fabric so it does not curl, and gives strong widthwise stretch and recovery, which is why cuffs and collars are ribbed. Interlock combines two layers of rib knitted together on the same two needle beds, producing a thicker, smoother, more stable fabric in which both faces look the same. These are standard textile definitions, not facts specific to this academy's own cast of companies.

The same three structures show up across different products, and the fastest test is comparing the two faces

Single jersey, rib and interlock are not equally common in every product, and reading a swatch's two faces is the quickest way to sort them before checking anything else.

Cedar & Co. asks Rowad Knits to confirm, in writing, what knit structure gives Order A's own fabric its look and feel

Cedar & Co., the academy's domestic, Make to Stock brand, is developing its own T-shirt range and wants a fabric with the same look and feel as Order A's 180 GSM T-shirt fabric. Cedar & Co. is not the buyer of Order A itself, but it asks Rowad Knits, the knitting mill that made Order A's fabric, to confirm in writing what knit structure produces that flat face, looped face, and curling raw edge.

Rowad Knits confirms in writing that Order A's fabric is single jersey: one needle bed, one flat face, one looped face, and the curl at a raw edge that single jersey always shows. Cedar & Co. can now brief its own factory using the same structure name with confidence.

Reusing Order A's own fixed fabric fact, correctly described

This lesson needs no new figure. Order A's fabric is already fixed at 180 GSM, Ne 30/1 combed cotton, 15,000 pieces (docs/02 section 7). The worked output here is not a calculation; it is a correct, one-sentence structural description, applied to that already-fixed fabric.

A two-step check for telling single jersey, rib and interlock apart

1. Look at the fabric's two faces. If one face is flat (knit) and the other is looped (purl), the fabric is single jersey.
2. If the two faces look the same, set single jersey aside and check the fabric's thickness and stretch instead.
3. Feel the thickness and stretch. A thinner fabric with strong widthwise stretch and recovery is rib.
4. Compare a thicker option to that same test. A thicker, more stable fabric with both faces alike is interlock.
5. Check for curling at a raw edge. Single jersey curls; rib and interlock, both built on two needle beds, do not.
6. Write down the structure name, not just "stretchy" or "thick", so the fact travels correctly to the next document.

A common mistake is assuming any two-faced knit is interlock, or that all stretchy knits are rib

A common mistake is assuming that any knitted fabric with two similar-looking faces is automatically interlock, or that all stretchy knits are rib. Rib and interlock both use two needle beds, so stretch behaviour alone does not tell them apart; a learner also has to check the fabric's weight and hand-feel, because interlock is markedly thicker and more stable than rib knitted from the same yarn. Skipping the thickness check and naming a fabric from stretch alone risks writing the wrong structure into a tech pack or a mill order, which the next lesson's construction detail (gauge, stitch length, GSM) cannot fix on its own.

• One flat face and one looped face, plus curling at a raw edge, always means single jersey.
• Two faces that look alike never means single jersey; it means rib or interlock instead.
• Strong widthwise stretch with no curling and a thinner hand usually means rib.
• Thick, smooth, stable, with both faces alike, usually means interlock.
• Order A's own fabric, 180 GSM Ne 30/1 combed cotton, is a single jersey, not a rib or an interlock.
• Stretch alone never tells rib and interlock apart on its own; always check thickness and hand-feel too.
• One needle bed produces single jersey; two needle beds produce rib or interlock.

Cedar & Co.'s buyer receives two unlabelled fabric swatches from a new mill and must name each one's structure

Cedar & Co.'s buyer is sourcing a second knitting mill and receives two fabric swatches, each with only a short description attached, no structure name given.

Which knit structure is each swatch, and which one belongs to the same family as Order A's own fabric? Decide before opening the answer.

Knit construction reference sheet: fill in the three main structures

Copy the three rows below into the knit construction reference sheet (introduced in lesson 2.1) so you always have single jersey, rib and interlock's own facts side by side when a new swatch arrives.

Download the Knit construction reference sheet (Excel)

Lesson 2.3: Reading a knitted fabric's construction: gauge, stitch length and GSM

You can now name single jersey, rib and interlock by their loop pattern and their face. The next lesson goes one level deeper: how gauge, stitch length and GSM describe any one of these structures precisely enough to write into a fabric specification. Back to the course map