A Roofing Felt Unit Conversion Reference for Import Orders
Keep dimensions, area and mass in separate fields. Accurate unit conversion helps compare roofing felt offers, but it cannot convert a product designation into a tested grade.
By Merily Waterproofing · Bulk supply for importers, distributors and building-material wholesalers
Convert dimensions before calculating area
Use metres consistently when multiplying width and length. One metre is 100 centimetres or 1,000 millimetres.
For example, 100 cm × 800 cm becomes 1 m × 8 m, giving 8 nominal m². Do not multiply mixed units without converting them.
Convert a real mass value, not an ambiguous label
One avoirdupois pound equals exactly 0.45359237 kg. Thus 20 lb is approximately 9.072 kg as a mathematical mass conversion.
A printed “20” or “20 lb” designation still needs interpretation. The arithmetic does not establish the actual mass of a particular roll or compliance with a roofing standard.
Keep precision appropriate to the information
Avoid giving an estimated roll mass many decimal places after conversion. Retain the original figure, unit and basis in the comparison.
Merily quotes identifiable roll specifications. Ask for the original mass basis rather than reconstructing an order solely from a wrapper number.
Put it in your buying record
| Quantity | Relationship | Buying note |
|---|---|---|
| Length | 1 m = 100 cm = 1,000 mm | Align units before area |
| Area | Width in m × length in m | Nominal, not net installed |
| Mass | 1 lb = 0.45359237 kg | Convert actual mass values |
| Shipment mass | Rolls × stated mass basis | Include other packing separately |
Questions buyers ask
Can I convert a No.30 designation into kilograms?
Not as though it were automatically a measured mass. Identify what the designation means first.
Should I keep both original and converted values?
Yes. It makes the source and calculation easier to audit.
Does more decimal precision mean a better measurement?
No. Precision should reflect the original information and measuring method.