Convert Centimetres per Second to gpd/ft²

Formula

gpd/ft² = cm/s × 21204.6221495

Derivation from SI units:

• 1 cm/s = 0.01 m/s.
• 1 gpd/ft² = 0.003785411784 m³ ÷ 86,400 s ÷ 0.09290304 m².
• 1 cm/s = 0.01 m/s ÷ 4.715952932099 × 10⁻⁷ m/s per gpd/ft² = 21204.6221495 gpd/ft²

Both units are defined exactly, so the factor is exact. Centimetre per Second definition: centimetre per second; Gallon per Day per Square Foot definition: US gallon per day per square foot.

Worked examples

1. A reading of 0.0001 cm/s converts to 2.120462215 gpd/ft².
   0.0001 cm/s × 21204.62215 = 2.120462215 gpd/ft²
2. A value of 0.1 cm/s is 2120.462215 gpd/ft².
   0.1 cm/s × 21204.62215 = 2120.462215 gpd/ft²

Where it's used

Centimetres per Second are used for constant-head and falling-head permeability tests, while US gallons per day per square foot appear in older USGS and well-driller reports. Both measure hydraulic conductivity (coefficient of permeability k), so the conversion is a fixed factor.

Centimetre per Second to other hydraulic conductivity units

Frequently asked questions

Sources

• The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 4 (derived units) and Table 8 (non-SI units accepted for use with the SI).
• Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "gallon (U.S.)".

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