Knitting Mill Cost Calculation

A circular knitting mill’s per-kilogram fabric cost equals yarn cost plus knitting conversion cost plus dyeing and finishing cost, where the yarn cost alone is calculated as (yarn price in USD/kg × fabric GSM × 1,000) ÷ (yarn count in tex × machine efficiency in %), and the knitting conversion charge typically runs USD 0.10 to 0.35 per kilogram before dyeing and finishing add USD 0.40 to 1.20 per kilogram depending on process complexity.

For a 150 GSM single jersey knitted from 20 tex cotton yarn at USD 3.20/kg, with 88% machine efficiency and a USD 0.18/kg knitting charge, finished fabric cost sits between USD 4.80 and USD 6.20 per kilogram before overhead and margin, a range that makes textile-engineering accuracy, not negotiation, the biggest lever on margin.

This guide walks through the four cost blocks a knitting mill accountant must price, the formulas that connect yarn count, fabric GSM, and machine gauge, the tolerance bands defined in ISO and ASTM standards, and the cost-reduction levers that survive a price-volume squeeze.

The Four Cost Blocks of a Knitting Mill

Every knitted fabric invoice can be broken into four blocks, and the relative weight of each block depends on the construction, fibre blend, and finishing route.

• Yarn cost: 55 to 65% of total fabric cost in most cotton and cotton-blend knits.
• Knitting conversion cost: 10 to 15%, covering machine depreciation, power, needles, and direct labour.
• Dyeing and printing cost: 15 to 22%, dominated by dye class (reactive, disperse, acid) and the number of process steps.
• Finishing and inspection cost: 5 to 10%, covering compacting, calendering, stentering, and quality control.

Cost engineering starts with the yarn block because a 1% error in yarn consumption modeling repeats across every kilogram the mill ships, while a 1% error in dyeing appears only once per dye-lot. This is why the formulas below get most of the engineering attention in a costing sheet.

Yarn Cost From Fabric GSM and Yarn Count

Yarn cost per kilogram of finished fabric is the single most important line in a knitting-mill cost sheet. The formula comes from a simple mass balance, where the number of meters of yarn needed to knit one square meter of fabric, multiplied by the mass of one meter of that yarn, gives the yarn mass per square meter. Dividing into the finished GSM yields fabric mass per kilogram of yarn consumed.

The worked calculation for a 160 GSM single jersey made from 24 tex combed cotton yarn at USD 3.60/kg, knitting at 87% efficiency:

1. Yarn length needed to knit one square meter of fabric = (160 × 100) ÷ (24 × 0.87) = 766 m/m². (This is the loop length plus waste figure, calculated loop-by-loop for the chosen stitch.)
2. Mass of one meter of 24 tex yarn = 24 / 1000 = 0.024 g.
3. Yarn mass per square meter of finished fabric = 766 × 0.024 = 18.4 g, giving a yarn-consumption ratio of 1 ÷ (18.4 ÷ 160) = 8.69 m of yarn per gram of fabric. Wait, recompute: this yarn-consumption ratio means 1 kg of yarn yields 54.3 kg of finished fabric.
4. Yarn cost per kg of fabric = 3.60 ÷ 54.3 = USD 0.0663 / kg of finished fabric × 1000 = USD 66.3 / kg of fabric on the yarn line alone? No: read carefully, the formula gives USD 3.60 ÷ (54.3 kg fabric per kg yarn), giving USD 0.0663 per kg of fabric for the yarn line. Stated in familiar units, yarn cost is USD 66.30 per 1,000 kg of finished fabric.

The point of the worked example is not the arithmetic, which a costing spreadsheet does in milliseconds, but the sensitivity. A drop in machine efficiency from 87% to 82% raises yarn consumption per kilogram of fabric by 6.1%, which at USD 3.60/kg yarn translates to USD 0.20/kg of additional yarn cost, larger than the entire knitting conversion charge on the same line. Machine efficiency, not yarn price, is usually the bigger lever.

Knitting Conversion Cost: Machine, Gauge, and Speed

Knitting conversion cost is the second block, covering everything the mill does on the knitting floor: machine depreciation, electricity, needle and cylinder replacement, direct operator labour, and indirect overhead. Costs are usually quoted per kilogram of fabric produced, which converts the line’s hourly operating cost into a per-kilogram figure using machine output.

Output per hour for a circular knitting machine follows three variables: number of feeders (F), feeder speed in revolutions per minute (RPM), and the number of courses knitted per revolution (CPR, which equals 1 for most plain circular knitting, higher for striping, jacquard, or miss-and-tuck patterning). The hour-output formula:

Output (kg/h) = (F × RPM × 60 × stitch length × GSM) ÷ (10⁶ × course density per cm × 100)

Where stitch length is in centimetres and course density is courses per centimetre of fabric length. Plugging in typical values for a 24-inch diameter, 24-gauge single-jersey machine running 24 feeders at 28 RPM with a stitch length of 0.28 cm and 16 courses per cm at 160 GSM gives approximately 18.4 kg/h. At a fully-loaded hourly cost of USD 4.80 (depreciation, power, labour, needles amortised), the conversion charge is USD 0.26/kg, comfortably inside the USD 0.10 to 0.35 industry band.

The non-obvious finding is that diameter, gauge, and feeder count matter far less than RPM and the percentage of shift time the machine is actually knitting. A 5% improvement in machine utilisation saves more than any needle or cylinder upgrade a mill can buy.

Dyeing and Finishing Cost

Dyeing cost is the most variable block. Reactive dyeing on cotton for pastels runs USD 0.25 to 0.45/kg of fabric; deep shades with three-bath processes climb to USD 0.70 to 1.00/kg; disperse dyeing on polyester sits in the USD 0.45 to 0.85/kg band; and yarn-dyed or piece-dyed mercerising adds further. Finishing includes compacting (USD 0.03 to 0.06/kg for cotton knit), stentering (USD 0.05 to 0.10/kg), calendering for selected finishes (USD 0.04 to 0.08/kg), and the dimensional-stability pass through a compactor that brings knitted loop distortion back inside ASTM D3887 tolerance bands.

The single biggest engineering question at the dyeing stage is liquor ratio. Modern low-liquor-ratio jet machines run at 1:5 to 1:7 versus the older 1:10 to 1:12 machines. A move from 1:10 to 1:6 cuts water, steam, and dye effluent volume by 40%, and since steam and effluent together account for roughly 60% of dyeing operating cost, the saving is material.

Cost Sheet Summary and the Standard Cost Sheet

The two standards most often cited on a knitted-fabric quality certificate, ISO 8388 (knitted-fabric types vocabulary) and ASTM D3887 (tolerance bands on knitted constructions), do not dictate cost directly. They do, however, define the dimensional and weight tolerance bands the mill must hold, and a mill pushing fabric weight closer to the lower tolerance saves yarn without violating the standard, a quiet but legal margin lever.

Five Cost-Reduction Levers That Survive a Volume Squeeze

When margins compress, mills look at four levers first: yarn, knitting, dyeing, and finishing. The list below ranks them by typical savings per kilogram, not by ease of implementation.

1. Knitting efficiency. Each one-point gain (87 to 88%) saves roughly 1.1% on yarn cost, the single highest leverage change a mill can make without capital investment, achievable through needle and cylinder replacement programs plus operator training.
2. Liquor-ratio reduction on the dye floor. Moving a cotton jet line from 1:10 to 1:6 cuts steam, water, and effluent cost by 30 to 40%, lifting dyeing margin by USD 0.10 to 0.20/kg depending on shade depth.
3. Yarn-count standardisation. A single-jersey line that can run 22, 24, and 26 tex in the same gauge drops knitting-needle changeover time by 50%, lifting effective machine hours per shift.
4. Process loss allowance. Most mills over-engineer the process-loss line. Reducing assumed loss from 4% to 3% without changing practice is unsustainable, but reducing it from 4% to 3% by tightening grey-fabric inspection saves real money.
5. Energy recovery. Exhaust-heat recovery on stenters and heat-recovery loops on dye-bath effluent cut thermal energy cost by 15 to 25% with payback periods under 18 months in most jurisdictions.

Frequently Asked Questions

What is the standard cost sheet format for a knitting mill?

The standard cost sheet lists yarn cost, knitting conversion cost, dyeing cost, finishing cost, labour and overhead, process loss allowance, and margin in that order, with each line shown per kilogram of finished fabric so that cost-share percentages add to 100%. The yarn line is calculated from GSM, yarn count, machine efficiency, and yarn price using the formulas shown above.

How is yarn consumption calculated for weft knitted fabric?

Yarn consumption in kilograms per square meter equals (stitch length in centimetres × number of wales per cm × number of courses per cm × yarn tex) ÷ 10⁶, multiplied by a machine-efficiency factor and an allowance for needle-loop distortion during finishing. Most mills use this formula with their own empirical corrections per construction.

What is the biggest variable cost in a knitting mill?

Yarn is the biggest variable cost for cotton and cotton-blend knits, typically 55 to 65% of finished fabric cost. The biggest controllable cost is the knitting-conversion line, because machine efficiency, utilisation, and gauge-needle changeover time all sit inside this line and respond to engineering discipline.

How does GSM tolerance affect knitting-mill profitability?

Knitted-fabric mass-per-unit-area tolerance is governed by ASTM D3887 and similar ISO standards. A mill producing fabric at the lower end of the tolerance band, for example 158 GSM against a target of 160 GSM ± 5%, uses less yarn without violating the standard. Across a year, this practice can lift yarn margin materially, but it must be managed against customer-specified nominal GSM.

Why does machine efficiency matter more than machine speed?

Machine efficiency captures the fraction of nominal speed that produces saleable fabric, accounting for stoppages, needle failures, yarn breakages, and stitch faults. A 28 RPM machine at 87% efficiency beats a 32 RPM machine at 72% efficiency on output and yarn cost together. Operating discipline, not raw RPM, drives mill margin.

References

• International Organization for Standardization. ISO 8388:2018, Knitted fabrics — Types — Vocabulary. iso.org — defines plain knit, rib, interlock, and purl constructions used in this article.
• International Organization for Standardization. ISO 4921:2000, Knitting — Basic terms — Vocabulary. iso.org — vocabulary source for knitting machine terminology.
• ASTM International. ASTM D3887/D3887M, Standard Test Method for Tolerances of Knitted Fabrics. astm.org — defines tolerance bands on courses per centimetre, wales per centimetre, and mass per unit area for weft knits.
• ASTM International. ASTM D3776/D3776M, Standard Test Methods for Mass Per Unit Area (Weight) of Fabric. astm.org — test method cited for GSM measurement.
• AATCC. AATCC Test Method 135, Dimensional Changes of Fabrics After Home Laundering. aatcc.org — used to verify knitted-fabric dimensional stability after finishing.
• Spencer, D. J. (2001). Knitting Technology: A Comprehensive Handbook and Practical Guide. Woodhead Publishing, Elsevier — chapter on circular knitting machine economics is the source for feeder-speed and output-per-hour formulas.

This article is the working reference for knitted-fabric cost engineering. Editorial by Iftay Khairul Alam, TextileTuts. Sources: ISO 8388, ISO 4921, ASTM D3887, ASTM D3776, AATCC TM-135, and Spencer (2001) as cited.