Copper wire weight chart — kg per km, and the copper in a 90 m coil

How conductor weight is worked out

The weight of a conductor follows from its cross-section and the density of copper, and nothing else: multiply the nominal area in square millimetres by 8.89 to get kilograms per kilometre. Every figure on this page is that one sum, applied to the IEC 60228 nominal sizes and then multiplied by the number of cores and by the coil length — so any row can be re-derived with a calculator, and any coil can be weighed against it.

One convenience worth remembering on site: kilograms per kilometre and grams per metre are the same number. 25 mm² is 222.3 kg/km and 222.3 g/m. So a metre cut off a coil, stripped bare and put on a kitchen scale, is a direct reading of the chart.

Copper wire weight chart: kg per km by size

One conductor, bare copper. Multiply by the number of cores for a finished cable.

0.75 mm² and 1 mm² are flexible-cord sizes built to IEC 60228 class 5, so the class 2 resistance column carries a dash for them. The weight column is unaffected: class 2 or class 5, thick strands or fine ones, a full-size 2.5 mm² conductor holds the same 22.2 g of copper in every metre. That is exactly why weight is the check that survives every construction difference.

Copper in a 90 m coil, by core count

Cable is bought by the coil in Pakistan, so this is the table that matters at the shop counter. Every figure is the conductor copper only — the coil on the scale will always read more than this, because insulation, sheath and drum sit on top.

Before this table can be used, one thing has to be asked at the counter: how many metres are in the coil? Coil length is not standard in Pakistan. Packs of 30 m, 45 m and 90 m are all sold, some sellers quote in feet or yards, and a rate given "per coil" means nothing until the length is stated. Ask for the length in the same message as the rate — the price per metre page covers converting between the units, and every quote we send names the coil length beside the figure.

Worked example: a 90 m coil of 25mm 4 core

Eighty kilograms is two men lifting it, and that is the point of knowing the figure before you buy: it tells you what the coil should feel like, what the freight will cost, and what the copper alone is worth. The same sum on 4 mm² three-core gives 35.6 × 3 × 0.090 = 9.61 kg, a coil one man carries. Products at both ends of that range are the 25mm 4 core standard cable and the 4mm 3 core standard cable.

Why weight verifies an honest cable

"Full gauge" is printed on a lot of cable in Pakistan and almost nobody publishes a test for it. Weight is that test. A conductor's area cannot be reduced without reducing its copper, its copper cannot be reduced without reducing its mass, and mass is the one property a buyer can measure with a scale rather than a laboratory.

Three checks, in order of how easy they are to run. None of them requires our figures to be taken on trust — each one is arithmetic you can repeat.

Two honest cautions on that method. First, it is a one-sided test: light is proof of a problem, heavy is not proof of quality, because sheath thickness, filler and drum weight all vary between makers and a heavier drum can mask a lighter conductor. Weigh the stripped metre if the gross figure is ambiguous. Second, an under-weight reading has innocent explanations too — a coil short of its stated metres weighs less for a reason that has nothing to do with the conductor, which is one more reason to confirm the coil length before the rate.

Strand geometry: what the standard sizes actually measure

IEC 60228 fixes the maximum resistance of a conductor, not its geometry. A compliant conductor's measured area therefore lands close to the nominal size without being identical to it, and the typical class 2 constructions below show how close. Use this table to convert a strand count and a caliper reading into an area you can compare against the weight chart.

A caliper on a single strand is the fastest check on site, and it is unforgiving in the right way: area goes with the square of the diameter, so a strand 5% thin is a conductor about 10% light. Flexible cable answers the same sizes with many more, finer strands — class 5 rather than class 2 — and the copper mass per metre is unchanged, which is the subject of flexible versus solid cable.

What the trade strand codes compute to

Pakistani shops sell by an imperial strand code — 7/.036 means seven strands of 0.036 inch — while the standards and this chart work in square millimetres. The two systems do not land on each other exactly. Below is what each code computes to, and the weight that follows from it, next to the nominal size the same cable is sold as.

The gap runs both ways, which is the part nobody prints. Through the middle of the ladder the code computes above the nominal it is sold as — 7/.029 is 2.98 mm² against a 2.5 mm² label, and 7/.036 is 4.60 mm² against 4, 15% more copper. At both ends it computes below: 3/.029 is 1.28 mm² against 1.5, 15% less; 7/.052 is 9.59 mm² against 10, 4% less; 7/.064 is 14.53 mm² against 16, about 9% less. So a coil weighed against the wrong system reads as short when it is not, or as generous when it is not. Fix the system first, then weigh. The full code-to-millimetre conversion, including the strand diameters behind each code, is on the Pakistan wire size chart; our own strand-code goods carry both figures on the page, as on 4mm 7/.036 single core copper cable and 6mm 7/.044 single core copper cable.

Aluminium weighs under a third of copper

Aluminium masses 2.70 kg/km per mm² against copper's 8.89, so the same nominal size weighs 30.4% of the copper version. That is why a big aluminium service cable can be pulled by hand where the copper equivalent needs a winch — and why it prices differently by weight.

The weight saving is real and the capacity cost is real with it: 25 mm² aluminium carries 87 A where copper carries 112 A, so matching a copper circuit usually means going up a size or two in aluminium. Aluminium earns its place on service drops and long feeders where the run is long and the terminations are large. The trade-off in full is in copper versus aluminium cable, and the sizes we draw are on aluminium cable.

Copper content, scrap value, and why a coil rate expires

The weight chart is also a scrap chart, because the copper recovered from a cable is the same copper that was priced into it. A 90 m coil of 4 mm² three-core holds 9.61 kg; strip an old run of 10 mm² two-core, 60 m of it, and you recover 88.9 × 2 × 0.060 = 10.7 kg. Multiply the kilograms by the day's scrap copper rate and you have the recovery value, before the dealer's deduction for insulation left on and for oxidised strands.

Strip old cable mechanically, with a stripper or a blade. Burning the insulation off is dangerous, fouls the air around whoever is doing it, and leaves an oxidised surface that a scrap buyer discounts — it destroys value rather than saving time.

The same arithmetic explains the thing buyers find hardest about cable pricing: a coil rate is only good for the day it was given. A 90 m coil of 25 mm² four-core has 80 kg of copper in it, so every rupee the copper rate moves moves that coil by eighty rupees, before anything else in the cable changes at all. That is why we quote on WhatsApp against the day's rate instead of printing a figure that goes stale, and why last week's quote is not a promise anyone in the trade can keep. It is also the whole of our factory-direct case: the same line that drew the copper answers the message, so the metal price is the price you are talking about, not a dealer's margin on top of it.

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