Convert Millimeters per Second to L/(m²·s)

Formula

L/(m²·s) = mm/s × 1

Derivation from SI units:

• 1 mm/s = 0.001 m ÷ 1 s = 1 L/(m²·s)
• 1 L/(m²·s) = 10⁻³ m³ ÷ (1 m² × 1 s) = 10⁻³ m/s = 1 mm/s
• 1 mm/s = 0.001 m/s ÷ 0.001 m/s per L/(m²·s) = 1 L/(m²·s)

Both units are defined exactly, so the factor is exact. Millimeter per Second definition: millimeter per second; Liter per Square Meter per Second definition: liter per square meter per second.

Worked examples

1. 1 mm/s is exactly 1 L/(m²·s).
   1 mm/s × 1 = 1 L/(m²·s)
2. A fabric tested at 250 mm/s is 250 L/(m²·s).
   250 mm/s × 1 = 250 L/(m²·s)

Where it's used

ISO 9237 results are written either way. They are identical: one litre per square metre per second is a 1 mm thick layer of air passing each second.

Millimeter per Second to other face velocity & air permeability units

Frequently asked questions

Sources

• The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 2 with SI prefix milli.
• ISO 9237:1995 Textiles — Determination of the permeability of fabrics to air, International Organization for Standardization , results expressed in mm/s.
• ISO 9237:1995 Textiles — Determination of the permeability of fabrics to air, International Organization for Standardization , air permeability expressed per unit area.
• The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 8 (litre).

Last reviewed: 2026-10-15. Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.