How to inspect knitted fabric with the 4-point system

Inspecting knitted fabric with the 4-point system means scoring every visible defect on a knit roll from 1 to 4 points by its length, capping each linear yard at 4 points, and normalising the total to 100 square yards so the roll can be judged against the buyer's limit. The rules come from ASTM D5430, the same standard used for wovens, but knits bring their own defects, their own limits and one practical problem: knit rolls are usually sold by weight, not length. This guide walks through the whole process as it is done in Tirupur, Erode, Karur and Ludhiana units.

What do you need before you start?

• The buyer manual. It gives the roll limit (knitwear buyers commonly use 20 to 28 points per 100 sq yd), the lot-average limit, the hole rule, the running-defect reject length, and the tolerances for width, GSM, shade and shrinkage.
• An inspection frame or table with a length counter, bright and even overhead lighting as the buyer manual specifies, and a way to see the fabric face side up at a steady speed.
• A GSM cutter and balance, a measuring tape and the approved shade swatch.
• A way to record defects with yard position: a printed sheet, or an app such as Fabric Inspection Software on an Android tablet.

Step 1: Sample the lot

Most buyer manuals ask for at least 10 % of the rolls in a lot to be inspected, chosen across every colour, width and construction, and 100 % when the previous lot from the same knitter failed. With 24 rolls of navy single jersey in a lot, that is a minimum of 3 rolls; pick them from different positions in the delivery rather than the top of the stack.

Step 2: Record the roll details and convert weight to length

Write down roll number, lot, shade, supplier, construction (single jersey, rib, interlock, fleece), GSM as ticketed, the roll weight and the open width. The 4-point formula needs length in yards, but a knit roll ticket usually shows kilograms. Convert it like this:

Length in metres = roll weight in kg × 1000 ÷ GSM ÷ width in metres

Example: a 25 kg roll of 180 GSM single jersey, 72 inches (1.83 m) open width. Area = 25 × 1000 ÷ 180 = 138.9 sq m. Length = 138.9 ÷ 1.83 = 75.9 m, which is 83.0 yards. If the frame has a length counter, use the counter reading instead and keep the calculated figure as a cross-check; a big gap between the two usually means the GSM is off.

Tubular or open width?

Many knits arrive in tubular form. Agree with the buyer whether the formula uses the opened width (twice the tube width) or the tube width, and write it on the report. Using the tube width for a fabric the buyer measures open doubles the points per 100 sq yd and can fail a good roll.

Step 3: Measure width, GSM and shade before inspecting

Measure width at the start of the roll, then again in the middle and at the end. Cut a GSM sample from the start. Compare shade against the approved swatch at the start, and against the previous roll in the lot. These results are recorded separately and are never converted into points, but they decide as many rejections as defects do.

Step 4: Inspect the face side and score each defect

Run the fabric face side up at a steady speed. For each defect, note the yard position, the defect type and its length, and award points:

Which defects matter most in knits?

Two rules apply throughout. No single linear yard can carry more than 4 points, however many defects fall in it. And running defects such as needle lines and barre earn 4 points for every yard they continue; many buyers reject the roll if a running defect exceeds a set length, commonly a few yards.

Step 5: Calculate points per 100 square yards

Points per 100 sq yd = total points × 3600 ÷ (length in yards × width in inches)

Continuing the example: the 83-yard, 72-inch roll has nine defects totalling 14 points after the per-yard cap. 14 × 3600 ÷ (83 × 72) = 50,400 ÷ 5,976 = 8.4 points per 100 sq yd. Against a 28-point knitwear limit, the roll is first quality. You can check any roll on the free 4-point system calculator, which also gives the per-100-sq-m figure for metric buyers.

Step 6: Grade the roll and the lot

Grade each roll First quality (at or under the limit) or Second quality (over it), or PASS and FAIL if the buyer uses those words. Then calculate the lot average across all inspected rolls and compare it with the lot-average limit, which for strict knitwear buyers is often 15 to 20. A lot can fail on its average even when every roll is under the roll limit. If the lot fails, most manuals require 100 % inspection of the remaining rolls.

Step 7: Report, label and claim

The report should carry the roll details, the defect log with yard positions, the points result against the limit, width, GSM, shade and shrinkage, and the inspector's sign-off. A roll map, with every defect plotted along the length, lets the cutting master avoid damaged zones. Our guide to the fabric inspection report format for export buyers lists every field. For any roll that fails, hold it uncut and raise a claim; see how to raise a debit note to a fabric mill.

How does Fabric Inspection Software help with knit inspection?

Fabric Inspection Software was designed in Coimbatore with knit units in mind. The defect master comes with knit defects (hole, needle line, lycra out, barre, oil mark) in Tamil, and you can add your own such as press-off, Hindi and English; inspectors can log by voice with both hands on the fabric where the tablet's speech recognition supports their language; the per-yard cap and running-defect rules are applied automatically; and the roll map, buyer PDF and debit note come from the same record. Tap logging works offline on a ₹10,000 Android tablet. It does not detect defects from camera images; the inspector finds them. See how the fabric inspection app works, or the plans from ₹4,999 a month.

Questions people ask

What is the usual 4-point limit for knitted fabric?

Knitwear buyers in the US and EU commonly set 20 to 28 points per 100 sq yd per roll, with a lot average of 15 to 20, which is tighter than the generic 40-point default. Always use the figure in your buyer's manual; Fabric Inspection Software stores each buyer's limit separately.

How do I find the length of a knit roll sold by weight?

Divide the roll weight in grams by the GSM to get the area in square metres, then divide by the width in metres. A 25 kg, 180 GSM roll at 1.83 m wide is 75.9 m, or 83 yards. Use the frame counter as the primary figure when you have one.

Is a needle line always a reject?

Not always. A needle line is a running defect, scored 4 points for every yard it continues, so a short one may still pass. Many buyer manuals reject a roll outright when a running defect exceeds a set length, often a few yards. Check the reject length in your buyer's manual.

Should knitted fabric be inspected tubular or open?

Inspect it in the form the buyer specifies and agree which width the formula uses. Using the tube width when the buyer measures the opened width doubles the points per 100 sq yd. Fabric Inspection Software prints the width used in the formula on every report, so the basis is visible to the buyer.