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Calculate coil weight – check the stated weight without scales

Measure the circumference with a tape measure or the wrap thickness with a folding rule. In just a few minutes, you can see whether the weight on the delivery note or label is plausible.

m

Place the tape measure tightly around the coil once; enter the value in metres (e.g. 5.655).

mm
Inner diameter

Rarely shown in the paperwork – usually 508, 610 or 762 mm.

t

Weight according to the delivery note or label – we will then show the deviation.

Result

Enter the measurements and press “Calculate weight”. Your entries remain in your browser.

When is an estimate useful?

When a coil is received or passed on without scales and the stated weight is in doubt – for example in the case of complaints, mixed-up coils or remaining stock. The calculator does not replace scales, but quickly shows whether a stated weight is far off.

How we calculate

The outer diameter is calculated from the circumference (OD = circumference ÷ π), or from the wrap thickness W (OD = ID + 2 × W). The weight is the volume of the winding multiplied by density and fill factor:

G = π/4 × (OD² − ID²) × B × ρ × f

G weight in tonnes, OD outer diameter, ID inner diameter, B strip width, W wrap thickness (dimensions in metres), ρ density in t/m³, f fill factor (air between the wraps).

Worked example

Width 1,250 mm, inner diameter 610 mm, circumference 5.655 m (outer diameter 1,800 mm), steel, tightly wound: around 21.7 t. A wrap thickness of 595 mm gives the same result.

How to measure correctly

  • Keep the tape measure tight and at right angles to the coil axis; do not measure over strapping or edge protectors.
  • Measure the wrap thickness at three points on the end face – top, left, right. Large differences indicate an oval coil; the range then becomes wider.
  • The inner diameter is rarely shown in the paperwork. The usual values are 508, 610 and 762 mm – if in doubt, measure it.
  • Select loosely wound coils and hot-rolled strip deliberately: they weigh less for the same dimensions.

How accurate is it?

The range is based on typical measurement uncertainties (tape measure ±10 mm at the circumference, folding rule ±5 mm, width ±2 mm) and a fill factor of ±0.01. Density and fill factor are values based on experience; only scales can show how well they match your coil. The result is therefore an estimate, not a weighing result.