SettingsSettings for this calculationUS
The weight of one square foot of the assembly, in pounds.
Enter a self-weight — the pounds a square foot of the build-up actually weighs. If the figure came off a loading schedule as a live or design load it is a pressure, and the honest metric equivalent is kN/m² rather than kg/m². Superimposed allowances for finishes and services belong here only when you mean their mass, not a factored load.
Weight per square metre
58.59 kg/m²
Converted using an exact defined factor of 4.882427636 kg/m² per lb/ft². Fixed by definition for a self-weight; if the figure is a design load, take the kN/m² route instead of this one.
- Conversion factor applied
- 4.88 kg/m² per lb/ft²
They open the calculator with your figures already in it
lb/ft² to kg/m² Calculator: 58.59 kg/m² — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- 1 lb = 0.45359237 kg and 1 ft = 0.3048 m, both exact, so 1 lb/ft² = 0.45359237 ÷ 0.09290304 = 4.882427636383050… kg/m². Note what this page does NOT do: a psf PRESSURE is 47.880 Pa, not 4.88 kg/m². The two share a number only because a pound weighs a pound-force at standard gravity, and a live load in psf belongs on the psf → kPa page instead.
Inputs used
- Weight per unit area (lb/ft²)
- 12
Intermediate steps
- Conversion factor applied
- 4.88 kg/m² per lb/ft²
Confidence note: Converted using an exact defined factor of 4.882427636 kg/m² per lb/ft². Fixed by definition for a self-weight; if the figure is a design load, take the kN/m² route instead of this one.
Add the equipment this sizes
This result is a specification — 58.59 kg/m² — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-08-26 · in the site-wide review of 2026-09-06 · v1.0.0
Regulatory standards & verification citations1
- 1 lb = 0.45359237 kg and 1 ft = 0.3048 m, both exact, so 1 lb/ft² = 0.45359237 ÷ 0.09290304 = 4.882427636383050… kg/m². Note what this page does NOT do: a psf PRESSURE is 47.880 Pa, not 4.88 kg/m². The two share a number only because a pound weighs a pound-force at standard gravity, and a live load in psf belongs on the psf → kPa page instead.
Cite this page
Your workspace
Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.
Everything here turns on what the psf figure means before you touch it. Read as a build-up — a roof assembly, a solar array, a topping — it is mass spread over area, and 12 lb/ft² is the 58.6 kg/m² a metric supplier will recognise. Read as a design load it is force spread over area, and no European code will accept kg/m²: 100 lb/ft² is 4.788 kN/m², reached by multiplying by 0.047880. Coming back, 1 kN/m² is 20.885 lb/ft². Both readings share one factor only because a pound-force and a pound-mass carry the same number under standard gravity, which is a coincidence of naming rather than a licence to swap them. Settle which one you hold, then convert.