Feet of Head to PSI Converter
Convert feet of head to psi. This head pressure calculator takes a height of liquid and gives the pressure it produces. For water, multiply feet by 0.433. For other liquids, multiply by the specific gravity as well. The result is also the static pressure under a column of liquid, such as at the bottom of a tank or the foot of a riser.
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How It Works
The pressure at the bottom of a column of liquid depends only on its height and density: P = ρ × g × h. A 10 ft column of water gives the same pressure in a 1/2 inch pipe as in a tank 10 ft across. Converting head to pressure gives that static pressure, or the pressure rise of a pump whose curve is read in feet.
On the conventional water basis, each foot of water adds 0.433528 psi. Multiply by the liquid's specific gravity (SG) for anything else: a brine of SG 1.2 adds 0.520233 psi per foot.
Formula
psi = feet of head × 0.433528 × SG
The 0.433528 factor uses the conventional water column (1,000 kg/m³, 9.80665 m/s²). Water at 60 °F (SG 0.9990) gives 0.433094 psi per foot, which rounds to the 0.433 quoted in plumbing references.
Worked Example
The water level in a storage tank sits 120 ft above a tap. The static pressure at the tap, with no water flowing, is:
120 × 0.433528 = 52.0234 psi
Feet of Head to PSI Table (water, SG 1.0)
| ft | psi | bar |
|---|---|---|
| 1 ft | 0.433528 psi | 0.0298907 bar |
| 2 ft | 0.867055 psi | 0.0597813 bar |
| 5 ft | 2.16764 psi | 0.149453 bar |
| 10 ft | 4.33528 psi | 0.298907 bar |
| 20 ft | 8.67055 psi | 0.597813 bar |
| 25 ft | 10.8382 psi | 0.747267 bar |
| 50 ft | 21.6764 psi | 1.49453 bar |
| 75 ft | 32.5146 psi | 2.2418 bar |
| 100 ft | 43.3528 psi | 2.98907 bar |
| 150 ft | 65.0291 psi | 4.4836 bar |
| 200 ft | 86.7055 psi | 5.97813 bar |
| 250 ft | 108.382 psi | 7.47267 bar |
| 300 ft | 130.058 psi | 8.9672 bar |
PSI per Foot of Head by Liquid
A foot of a denser liquid presses harder than a foot of water. For a liquid not listed, take its SG from the supplier datasheet and enter it above.
| Liquid | 1 ft |
|---|---|
| Water, conventional (SG 1.000) | 0.433528 psi |
| Water at 60 °F / 15.6 °C (SG 0.9990) | 0.433094 psi |
| Water at 20 °C / 68 °F (SG 0.9982) | 0.432747 psi |
| Water at 60 °C / 140 °F (SG 0.9832) | 0.426244 psi |
| Water at 80 °C / 176 °F (SG 0.9718) | 0.421302 psi |
| Seawater (SG 1.025) | 0.444366 psi |
SG here is relative to 1,000 kg/m³. A datasheet SG referenced to water at 60 °F differs by 0.1%, which you can ignore.
Going the other way? Use the psi to feet of head converter. For the head a pump has to deliver, including pipe friction, use the total dynamic head calculator.
FAQ
Common questions about converting feet of head to psi.
Frequently Asked Questions
How do I convert feet of head to psi?
Multiply feet by 0.433528 for water. For example, 100 ft × 0.433528 = 43.3528 psi. For another liquid, multiply the result by its specific gravity.
How many psi is 1 foot of water?
One foot of water column is 0.433528 psi on the conventional basis, or 0.433094 psi with water at 60 °F, which rounds to the 0.433 in most plumbing references.
How much pressure does a water tower give?
Just over 0.43 psi for every foot the water level sits above the tap. A level 100 ft above a house gives 43.4 psi static. While water flows, the pressure at the tap is lower by the friction loss in the mains.
How many psi is 50 feet of head?
50 ft of water column is 21.6764 psi. Multiply by the specific gravity for other liquids.
Does the pressure depend on the width of the pipe or tank?
No. Static pressure depends only on the height of the liquid and its density, not on the width of the column. A narrow riser and a wide tank of the same height give the same pressure at the bottom.
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