Gallon per Day per Square Foot (gpd/ft²)
The gallon per day per square foot, once called the Meinzer unit, is the older US groundwater unit of hydraulic conductivity: 1 gpd/ft² ≈ 0.0408 m/day.
Symbol: gpd/ft² (ASCII: gpd/ft2)
Quantity: hydraulic conductivity (coefficient of permeability k)
SI relation: 1 gpd/ft² = 4.715952932099 × 10⁻⁷ m/s (exact)
Derivation: 1 gpd/ft² = 0.003785411784 m³ ÷ 86,400 s ÷ 0.09290304 m².
Exact: yes, by definition
Typical uses
- Older USGS and well-driller reports
- Converting historical aquifer data
Convert US gallons per day per square foot to other units
| Conversion | 1 gpd/ft² equals | Reverse |
|---|---|---|
| gpd/ft² to metre per second | 4.715952932 × 10⁻⁷ m/s | metre per second to gpd/ft² |
| gpd/ft² to centimetre per second | 0.00004715952932 cm/s | centimetre per second to gpd/ft² |
| gpd/ft² to metre per day | 0.04074583333 m/day | metre per day to gpd/ft² |
| gpd/ft² to centimetre per hour | 0.1697743056 cm/h | centimetre per hour to gpd/ft² |
| gpd/ft² to millimetre per hour | 1.697743056 mm/h | millimetre per hour to gpd/ft² |
| gpd/ft² to foot per day | 0.1336805556 ft/day | foot per day to gpd/ft² |
| gpd/ft² to inch per hour | 0.06684027778 in/h | inch per hour to gpd/ft² |
Open the Hydraulic Conductivity Converter (cm/s, m/day) to convert any value between all units.
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.)".
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Gallon per Day per Square Foot (gpd/ft²). Retrieved October 29, 2026, from https://scientificconverters.com/units/us-gallon-per-day-per-square-foot/
IEEE
Scientific Converters, "Gallon per Day per Square Foot (gpd/ft²)," scientificconverters.com. Accessed: Oct. 29, 2026. [Online]. Available: https://scientificconverters.com/units/us-gallon-per-day-per-square-foot/