How Much Fabric Do You Need Per Dozen T-Shirts? The Real Production Formula

Sales Intan Jaya Tekstil
5 days ago
5 min read

One of the most common questions that comes into fabric suppliers — including us at IJT — is this:

"How many kilograms of fabric do I need to produce one dozen size M t-shirts?"

Simple question. The answer is not so simple.

Many garment manufacturers and small clothing operations estimate fabric requirements based on guesswork — or based on "what we ordered last time." The result: some end up with leftover fabric they can't use, others run short mid-production and scramble to reorder, risking a dye lot mismatch in the process.

This article gives you the formula that's actually used in real production — with worked examples you can apply immediately.

Why Fabric Estimates So Often Go Wrong

Before getting into the formula, it's worth understanding why so many fabric estimates miss the mark.

Three factors that get ignored most often:

1. Not accounting for actual fabric width

The same fabric type can come in different widths depending on the supplier and the knitting machine used. Tubular (circular) fabric and open-width fabric are calculated differently. If you're working from a standard number without checking the actual width of the rolls you're using, your calculation is already off before you start.

2. Not building in allowance for shrinkage and cutting waste

Knit fabrics shrink after washing — typically 3–8% depending on the fabric type and finishing process. Cutting waste is also real: fabric trimmings at pattern edges, unusable roll ends, trial cuts. If these aren't factored in, you will always come up short.

3. Assuming all sizes require the same amount of fabric

A size S and a size XL t-shirt don't just have different patterns — they require meaningfully different amounts of material. Mixed-size productions calculated with a single average number consistently produce estimates that don't match reality.

What You Need Before You Calculate

Before using any formula, have these four numbers ready:

Garment body length — shoulder to hem, in cm
Garment body width — chest width (half chest circumference), in cm
Actual fabric width — measure it yourself from the rolls you'll be using, in cm
Fabric type — tubular or open width (this changes how you calculate)

If you don't have finalized pattern specs yet, use standard size measurements as a preliminary estimate — but update the calculation before placing a large fabric order.

The Core Formula: Tubular (Circular Knit) Fabric

Tubular fabric is knit fabric that comes off the machine in cylinder form — two layers still joined at both edges. The majority of combed and carded knit fabric sold in the market comes in this form.

Because it's two layers, one "width" of tubular fabric already covers both the front and back panels of a t-shirt simultaneously.

Basic formula per piece:

Fabric required (meters) = (Garment length + allowance) × 2 / 100

But this is too simplified for real production. The more accurate formula:

Fabric required per piece (kg) =
  [(Body length + 10 cm allowance) × (Body width × 2 + 10 cm allowance)]
  × GSM / 10,000,000

Worked example:

Adult t-shirt, size M:

Body length: 68 cm
Body width: 50 cm (half chest circumference of 100 cm)
Fabric GSM: 180 (combed 24s)
Length allowance: 10 cm
Width allowance: 10 cm

= (68 + 10) × (50 × 2 + 10) × 180 / 10,000,000
= 78 × 110 × 180 / 10,000,000
= 1,544,400 / 10,000,000
= 0.154 kg per piece

Per dozen (12 pieces): 0.154 × 12 = 1.85 kg

Add Allowance for Shrinkage and Waste

The number above is the theoretical requirement — ideal conditions with zero waste and zero shrinkage. In real production, always add:

Fabric shrinkage: 5% (safe figure for standard combed cotton)
Cutting waste: 5–8% (depending on pattern complexity and your cutting team's skill level)

Safe total allowance: 10–15%

From the example above:

1.85 kg × 1.12 (12% allowance) = 2.07 kg per dozen

For a production run of 10 dozen size M t-shirts in combed 24s at 180 GSM, the safe fabric requirement is approximately 20–21 kg.

What If You're Producing Mixed Sizes?

This is where estimates go wrong most often.

If you're filling one order with multiple sizes — S, M, L, XL — each size has a different fabric requirement. Do not use a single average number across all sizes.

The correct approach:

Calculate the requirement for each size separately, then add them up.

Example: an order of 5 dozen with this size breakdown:

1 dozen S → estimated 1.7 kg/dozen × 1.12 = 1.90 kg
2 dozen M → estimated 1.85 kg/dozen × 1.12 = 2.07 kg × 2 = 4.14 kg
1 dozen L → estimated 2.0 kg/dozen × 1.12 = 2.24 kg
1 dozen XL → estimated 2.2 kg/dozen × 1.12 = 2.46 kg

Total: 1.90 + 4.14 + 2.24 + 2.46 = 10.74 kg

If you used "2 kg per dozen" as a flat average for all sizes, you'd order 10 kg — and come up nearly 0.75 kg short mid-production.

Quick Reference Table

Estimated fabric requirement per dozen for standard adult t-shirts, combed cotton, with 12% allowance:

Size	Body Length (cm)	Body Width (cm)	Est. per Dozen (kg)
S	64	46	~1.9 kg
M	68	50	~2.1 kg
L	72	54	~2.4 kg
XL	76	58	~2.7 kg
XXL	80	62	~3.0 kg

Note: these estimates are based on 180 GSM and tubular fabric at 70–75 cm width. Recalculate using your actual pattern measurements and fabric specs before placing any large order.

Two Steps Before You Place Your Fabric Order

Once you have your fabric requirement figure, two final steps before ordering:

Confirm the actual fabric width with your supplier. Ask for the width of the specific rolls that will be shipped — not the "standard" width listed in the catalogue. Actual width can differ, and that directly affects your calculation.
Add a buffer for samples and QC. Before full production runs, you'll typically sew a few pieces first to check sizing and fit. Set aside an extra 1–2 kg for this purpose, separate from your main production requirement.

The Bottom Line

Calculating fabric requirements isn't about guessing, and it's not about repeating last order's number. It's about having a figure you can stand behind — so you can order precisely, without overstocking or coming up short mid-production.

The formula in this article isn't complicated. But many garment operations don't use it simply because they didn't know it existed — and keep paying the cost of over- or under-ordering on every production run.

Starting from your next order: calculate first. Order after.

Want to know exactly how much fabric you need for your next production spec? The IJT team can help you work it out before you order — so you get the right quantity from the same lot.

Contact our 24hr CS at WA 0812 9090 2360 or

contact our store admin at office hours (Monday - Friday 09.00 - 17.00 and Saturday 09.00 - 17.00, Sunday off) at WA 0812 1234 2360

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