Convert Gallons per Day per Square Foot to cm/s

Formula

cm/s = gpd/ft² × 0.00004715952932099

or cm/s = gpd/ft² ÷ 21204.6221495

Derivation from SI units:

• 1 gpd/ft² = 0.003785411784 m³ ÷ 86,400 s ÷ 0.09290304 m².
• 1 cm/s = 0.01 m/s.
• 1 gpd/ft² = 4.715952932099 × 10⁻⁷ m/s ÷ 0.01 m/s per cm/s = 0.00004715952932099 cm/s

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

Worked examples

1. A reading of 100 gpd/ft² converts to 0.004715952932 cm/s.
   100 gpd/ft² × 0.00004715952932 = 0.004715952932 cm/s
2. A value of 1000 gpd/ft² is 0.04715952932 cm/s.
   1000 gpd/ft² × 0.00004715952932 = 0.04715952932 cm/s

Where it's used

Gallons per Day per Square Foot are used for older USGS and well-driller reports, while centimetres per second appear in constant-head and falling-head permeability tests. Both measure hydraulic conductivity (coefficient of permeability k), so the conversion is a fixed factor.

Gallon per Day per Square Foot to other hydraulic conductivity units

Frequently asked questions

Sources

• 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.)".
• 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).

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