Feet of Head to PSI Converter
Pressure at the bottom of a liquid column depends on the height of the column and the density of the liquid per P = ρgh. For water at 4°C (density 62.4 lb/ft³), each foot of head...
Formula
Source: Engineering Toolbox, Hydraulic Institute Standards | Last reviewed: June 7, 2026
Examples
100 ft
= 43.3 psi
- SG = 1
100 ft of water
100 ft
= 34.6 psi
- SG = 0.8
100 ft of kerosene (SG 0.8)
231 ft
= 100 psi
- SG = 1
231 ft of water = 100 psi
Quick Reference Table
| ft head | psi |
|---|---|
| 10 | 4.33 |
| 20 | 8.66 |
| 50 | 21.65 |
| 100 | 43.3 |
| 200 | 86.6 |
| 500 | 216.5 |
Where is this used?
Sizing pressure gauges at pump discharge.
Determining the discharge pressure of a pump given its head rating and the fluid being pumped.
In municipal water supply systems, the booster pump discharge head (e.g., 200 ft of head at the pump curve) is converted to discharge pressure (86.6 psi for water) to specify the downstream pressure reducing valve setting and the customer-side allowable pressure range.
A 250 ft head pump delivering 1,000 GPM of water will produce 108 psi at the discharge flange, but if the same pump is moved to a 30% glycol service (SG 1.05), the discharge pressure becomes 113 psi at the same flow rate, requiring a higher-pressure-rated mechanical seal and a different relief valve setting.
Building fire pump selection per NFPA 20 specifies the rated net pressure in psi (e.g., 100 psi for a 200 ft head system at sea level) which corresponds to the pump curve head at the design flow — converting between head and pressure is required for both the pump specification and the system hydraulic calculation.
In oil pipeline operations, the pump station discharge head (often 2,000–3,000 ft of head for long-distance crude transport) translates to 866–1,299 psi for 30°API crude (SG 0.876) at the design temperature, and the conversion must use the operating temperature SG (not the standard 60°F SG) for accurate pressure ratings.
Cooling tower sump pump and condenser water pump specifications use head-to-pressure conversion to set the maximum system pressure and the pressure relief valve setpoint — a 60 ft head cooling tower circulating pump producing 1,500 GPM will deliver 26 psi at the riser base, requiring the riser piping to be rated for at least 50 psi working pressure with a safety margin.
Mining slurry pump applications present the most challenging head-to-pressure conversions: a 200 ft head pump moving 2.0 SG iron ore slurry delivers 173 psi at the discharge, requiring heavy-wall pipe, high-pressure rated valves, and specialized seals designed for abrasive service.
Hydroelectric plant penstock design uses head-to-pressure conversion in reverse: a 500 ft gross head hydro plant produces 217 psi at the turbine inlet, requiring the penstock, inlet valve, and turbine casing to be rated for that pressure with appropriate surge allowance for water hammer events.
Industry Standards Referenced
Frequently Asked Questions
Where does the 0.433 factor come from?
0.433 = 62.4 lb/ft³ (water density) ÷ 144 (in²/ft²). It is the pressure exerted by a 1-ft column of water at 4°C.
Does temperature affect the conversion?
Yes, slightly. Water density changes with temperature: at 200°F, water density is about 60.1 lb/ft³, so the factor drops to 0.417. For most applications, 0.433 is sufficient.
How do I convert meters of head to psi?
First convert meters to feet (multiply by 3.281), then use the formula above. For water, psi = meters × 1.42.
Reviewed for accuracy
Reviewed against ANSI/HI 9.6.1 pump head standards · Last reviewed: June 7, 2026
All calculations are for reference only. Always verify with manufacturer data and a qualified engineer for critical applications. Learn about our editorial process.