Convert felt areal weight or apparent density using thickness. Calculated values do not establish material suitability.
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Results are rounded for display. Keep the original values, measurement method and conditions in your project record.
How to convert felt areal weight and thickness to density
Apparent density (kg/m³) = areal weight (g/m²) ÷ thickness (mm). The gram-to-kilogram and millimetre-to-metre factors cancel in this relationship.
To express that density in g/cm³, divide the kg/m³ value by 1,000. To calculate areal weight in g/m² from density in kg/m³, multiply the density by thickness in mm.
A worked example
For an illustrative material with areal weight 1,000 g/m² and measured thickness 5 mm, apparent density is 1,000 ÷ 5 = 200 kg/m³, or 0.2 g/cm³. These example values demonstrate the calculation; they are not a Feltova stock grade, test result or tolerance promise.
Why does the thickness measurement condition matter?
Use a defined thickness method and record the measurement pressure or other agreed conditions. A different thickness value changes the calculated apparent density even when the areal weight stays the same.
For background on the separate measurements, ASTM D1777-26 addresses textile thickness and ASTM D3776/D3776M-20(2025) addresses mass per unit area. Agree the applicable method and edition for your material; using this calculator does not demonstrate compliance with a test standard.
Can I use values for an adhesive-backed or layered construction?
Identify what each value includes. If areal weight includes adhesive or other layers, a calculation using the complete construction’s thickness describes that construction. It should not be presented as the density of the felt face alone. Keep the material scope consistent across both inputs.
What belongs in the material specification?
Record the material reference, original values, units, measurement methods and conditions, and any required tolerances. See the felt material specification checklist and the felt sample review record before comparing supplier data or approving a sample.
For project review, send Feltova your material requirements and drawing. State whether density, areal weight and thickness are specified or remain open for review.