Vapor Permeability Converter
Water vapor permeability describes how readily moisture diffuses through a building material — the number behind vapor-barrier ratings. SI work uses kilograms per pascal second square meter; North American codes use the perm, and perm-inches when the rating is per inch of thickness.
5 units supported Base unit kilogram per pascal second m² (kg/(Pa·s·m²))
Multiply the number of kilograms per pascal second m² by 17478392337.5 to get perms (0 °c). How this is calculated
About vapor permeability conversion
Vapor Permeability conversion is commonly needed when vapour barriers, building envelope design, and moisture control. Building codes call anything under 1 perm a vapour retarder; the rating depends on the reference temperature, so 0 °C and 23 °C values both circulate.
Convert Kilogram per Pascal Second m² to other vapor permeability units
1 kg/(Pa·s·m²) expressed in every other vapor permeability unit on this site.
- Kilogram per Pascal Second m² kg/(Pa·s·m²) 1
- Perm (0 °C) perm (0 °C) 17,478,392,000
- Perm (23 °C) perm (23 °C) 17,405,683,000
- Perm-inch (0 °C) perm·in (0 °C) 688,125,680,000
- Perm-inch (23 °C) perm·in (23 °C) 685,263,110,000
Complete list of vapor permeability units
All 5 units this converter supports, each stated against the kilogram per pascal second m² (kg/(Pa·s·m²)).
| Unit | Symbol | System | In kilograms per pascal second m² | Conversions |
|---|---|---|---|---|
| Kilogram per Pascal Second m² | kg/(Pa·s·m²) | SI | base unit (kg/(Pa·s·m²)) | — |
| Perm (0 °C) | perm (0 °C) | US | 1 perm (0 °C) = 5.72135e-11 kg/(Pa·s·m²) | — |
| Perm (23 °C) | perm (23 °C) | US | 1 perm (23 °C) = 5.74525e-11 kg/(Pa·s·m²) | — |
| Perm-inch (0 °C) | perm·in (0 °C) | US | 1 perm·in (0 °C) = 1.4532229e-12 kg/(Pa·s·m²) | — |
| Perm-inch (23 °C) | perm·in (23 °C) | US | 1 perm·in (23 °C) = 1.4592935e-12 kg/(Pa·s·m²) | — |
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Frequently asked questions
What is the base unit for vapor permeability?
Vapor Permeability conversions on this site are calculated against the kilogram per pascal second m² (kg/(Pa·s·m²)).
Which vapor permeability units can I convert?
You can convert between 5 units, including kilogram per pascal second m², perm (0 °c), perm (23 °c), perm-inch (0 °c), and more.
Where is vapor permeability conversion useful?
It is commonly needed when vapour barriers, building envelope design, and moisture control.
Does this converter mix measurement systems?
The converter supports SI, US units and keeps their exact definitions separate so results stay accurate.
Related categories
Conversion factors are based on internationally agreed unit definitions. See our methodology and sources for details on how these values are verified.