What this converter does
This converter changes hydraulic conductivity between ft/day, cm/s, m/day, m/s and darcy. It is useful when US groundwater figures must feed a metric seepage or soil-mechanics model. Every pair uses an exact factor, so results stay precise. Type a value and read the answer instantly.
Because 1 ft/day is only 3.53×10⁻⁶ m/s, US permeability numbers look far larger than their metric equivalents.
The units it covers
Hydraulic conductivity units, each expressed against the metre per second.
View all units & their values
| Unit | Symbol | Value | Mainly used |
|---|---|---|---|
| Metre per second | m/s | 1 | SI, soil mechanics |
| Centimetre per second | cm/s | 0.01 | Lab test reporting |
| Metre per day | m/day | 1.1574e-5 | Groundwater flow |
| Foot per day | ft/day | 3.5278e-6 | US hydrogeology |
| Darcy | darcy | 9.6699e-6 | Petroleum, ≈ water at 20°C |
The formula
Each unit has a fixed value in m/s, so any pair converts through m/s:
result = value × factor_from ÷ factor_toWhere:
- value = the number you typed
- factor_from = the “from” unit in m/s
- factor_to = the “to” unit in m/s
Worked example
Convert 100 ft/day to m/s.
1 ft/day = 3.5278e-6 m/s100 × 3.5278e-6 = 3.53e-4 m/sSo 100 ft/day is about 3.5×10⁻⁴ m/s — a permeable sand.
The units in this example
A US hydrogeology unit for groundwater flow and aquifer permeability.
- 1 ft/day = 3.528e-6 m/s
- 1 ft/day ≈ 0.305 m/day
- sand ≈ 5–500 ft/day
- clay < 0.01 ft/day
The SI unit of hydraulic conductivity used in soil mechanics and seepage analysis.
- 1 m/s = 100 cm/s
- 1 m/s ≈ 283,465 ft/day
- 1 m/s = 86,400 m/day
- gravel ≈ 1e-2 m/s