Buying Fabric by the Kilo: Converting a Price per Kilo to a Price per Metre

Most fabric shops sell by length: a price per metre or per yard, cut from the roll at a fixed width. But a good deal of fabric is sold by weight instead. Knit fabrics from mills and wholesalers are often priced per kilogram, deadstock and end-of-roll lots are frequently sold by the kilo, and yarn is almost always sold by weight. A price per kilo is hard to compare with a price per metre until you know how many metres there are in a kilo of that particular cloth. This guide shows how to convert one into the other with the Fabric Weight from Dimensions tool, works through two examples, and covers the traps that make a cheap-looking kilo price expensive.

Why some fabric is sold by weight

Knits are the main example. A knitted fabric stretches, so measuring a length off the roll accurately is harder than with a woven, and the width of a knit can vary as it relaxes. Weight does not change when you pull on the fabric, so mills and wholesalers often find it the fairer measure. Knits made on circular machines also come off the machine as a tube, and whether they are sold tubular or slit open changes the width you get.

Deadstock and remnants are another. A seller clearing a warehouse of assorted ends of rolls cannot sensibly measure and price each piece, so they weigh them and sell by the kilo. And many mills price by weight because their own costs, yarn above all, are by weight.

The conversion

You need two facts about the fabric: its GSM (grams per square metre) and its width. From those, the weight of one running metre is:

grams per running metre = GSM × width in metres

and from that:

price per metre = price per kilo × grams per running metre ÷ 1000

metres per kilo = 1000 ÷ grams per running metre

The dimensions tool gives you the grams per running metre directly: enter the GSM, a length of 1 m, and the width in centimetres.

Example 1: a cotton jersey at 180 GSM, 180 cm wide

A typical T-shirt-weight cotton jersey might be 180 GSM. Suppose it is sold open width at 180 cm, for a price of 12 per kilo in your currency.

• One running metre is 1.8 m² and weighs 324 g.
• Price per metre: 12 × 324 ÷ 1000 = 3.89.
• Metres in a kilo: about 3.09.

A 25 m roll of this fabric would weigh 8.1 kg by the same calculation. So a kilo buys you just over three metres. If a shop down the road sells a similar jersey at 150 cm wide for 4.50 a metre, you can now compare like with like, though remember that a narrower width also yields less per metre.

Example 2: a heavier fleece at 280 GSM, 160 cm wide

Now a sweatshirt fleece at 280 GSM and 160 cm, at the same 12 per kilo.

• One running metre weighs 448 g.
• Price per metre: 12 × 448 ÷ 1000 = 5.38.
• Metres in a kilo: about 2.23.

The kilo price is identical, but the fleece costs about 38% more per metre because each metre is heavier. This is the central point of buying by weight: at the same price per kilo, heavier and wider fabrics cost more per metre. A kilo price only looks like a bargain once you know what a metre weighs.

Working from metres you need to kilos you buy

Usually you know how much fabric a project needs as a length. The Fabric Yardage Calculator will give you that length from the area and the usable width. Multiply the length by the grams per running metre to get the kilos to order. For four metres of the jersey above, that is 4 × 324 g, or about 1.3 kg. Sellers often round lots to the nearest half or whole kilo, so expect to buy a little more.

Where the GSM and width come from

For new fabric from a mill or wholesaler, both should be on the listing or the spec sheet. If only ounces per square yard are given, convert with the Fabric Weight Converter first. For deadstock or remnants with no paperwork, measure:

1. Measure the width from selvedge to selvedge, and the usable width inside any pin holes or printed edge.
2. Cut a 10 cm by 10 cm square, or several, and weigh them on a scale reading to 0.1 g. Grams for one square, times 100, is the GSM.
3. If you cannot cut a sample, weigh a whole piece and measure its length and width; GSM is the weight in grams divided by the area in square metres.

Traps when buying by weight

Tubular versus open width

A circular knit sold as a tube has two layers. If the listing says "90 cm tubular", you get 180 cm of fabric when it is slit open, minus a little for the crease and any edge that curls. Make sure you know which width the GSM and the price refer to.

Moisture and finish

Fabric weight changes with humidity, and natural fibres such as cotton and wool take up much more moisture than synthetics. Unwashed fabric may also carry finishing chemicals that wash out. Neither usually changes the weight by more than a few percent, but on a large order a few percent is real money. Ask how the seller weighs.

Shrinkage

Knits, especially cotton knits, can shrink noticeably in the first wash. A kilo that would have given 3.09 m unwashed gives less length after washing, because the same weight now occupies a smaller area. Test a piece with the Fabric Shrinkage Calculator before cutting a whole order.

Mixed lots

Remnant lots sold by the kilo can include pieces too small or too damaged to use. A low kilo price for a mixed bag is not the same as a low price for usable fabric. Estimate how much of the lot you will actually cut from.

Packaging included in the weight

Some sellers weigh fabric on the roll or in the bag. For small lots, the packaging can be a noticeable share of the weight. Ask for net weight.

Comparing quotes from different sellers

To compare one seller who quotes per kilo and another who quotes per metre, convert both to the same basis. The cleanest basis is usually the price per square metre, which strips out width as well as weight:

• From a per-metre price: divide by the width in metres.
• From a per-kilo price: multiply by GSM and divide by 1000.

For the 180 GSM jersey at 12 per kilo, that is 2.16 per square metre. A per-metre price of 3.89 at 180 cm wide comes to the same thing, which is a useful check that your arithmetic is consistent.

Price is not the only thing to compare, of course. Two jerseys of the same GSM can differ in yarn quality, fibre, knit structure and finishing. A spec sheet that gives yarn counts lets you compare them more closely; the yarn count converter puts different systems on one scale.

What the calculation does not account for

The dimensions tool multiplies a single GSM by a rectangle. Real fabric varies a little in weight across and along the roll, quoted widths may include selvedges you cannot use, and knitted fabric can change width as it relaxes after being unrolled. The conversion is accurate for the numbers you give it; the uncertainty lives in the GSM and width. If the purchase is large, ask the seller for a sample and weigh it yourself before you commit.

Summary

To turn a price per kilo into a price per metre, find the fabric's grams per running metre (GSM times width in metres) and scale the kilo price by it. At the same price per kilo, heavier and wider fabrics cost more per metre, which is why a kilo price on its own tells you very little. Measure or ask for the GSM and the width, check whether a knit is tubular or open, and allow for shrinkage before you decide how many kilos you need.