How do you convert feet of head to PSI?

Use PSI = feet of water × 0.4335 (at about 60°F). This calculator uses 0.4335 psi/ft as the default but also lets you adjust for water temperature.

What is 1 PSI in feet of water?

1 psi ≈ 2.31 ft of water at 60°F. We simply invert the 0.4335 psi/ft factor: ft = psi ÷ 0.4335.

Why does water temperature matter?

The pressure from a water column depends slightly on water density, which changes with temperature. For most plumbing work 60°F (15.6°C) is accurate enough, but in lab/industrial calculations you might want to pick the exact temperature.

Feet of Water to PSI Converter

Convert feet of water column (ft H2O) to PSI and back. Use standard 60°F water or change temperature to see the effect on pressure. Includes quick chart, formula and FAQ for plumbing, HVAC and pumping.

Full original guide (expanded)

Feet of Water to PSI Converter

Convert water column height to pressure: ft H₂O → psi and psi → ft H₂O. Default is 60°F water (1 ft ≈ 0.4335 psi). You can tweak water temperature for more precise engineering work.

Feet of water (ft H₂O)

Head of water above the gauge

Pressure (psi)

psi = ft × factor

Reverse: PSI → Feet of Water

psi

Enter known pressure

Feet of water (ft H₂O)

ft = psi ÷ factor

Current factor:0.4335 psi per ft

1 psi in ft H₂O:2.306 ft

Quick table (60°F)

ft of water	psi	Notes
1 ft	0.4335	Base factor
5 ft	2.1675	Small elevation
10 ft	4.3350	Common pump calc
25 ft	10.8375	≈ 11 psi
50 ft	21.6750	Two-storey equivalent

Formula for feet of water to psi

psi = ft H₂O × 0.4335 (at ~60°F)

More generally:
psi = (ft × ρ × g) ÷ 144

where ρ is water density (lb/ft³), g = 32.174 ft/s², and 144 is in² per ft².

Why 0.4335?

It comes from the weight of a 1 ft column of water over 1 square inch. Most plumbing charts round this to 0.433 or even 0.434. This tool uses 0.4335 as a practical default.

FAQ

1. How accurate is this for hot water?

Hot water is slightly less dense, so it makes a little less pressure for the same height. Choose 212°F preset to see the effect — you’ll get around 0.338 psi/ft instead of 0.4335.

2. Can I use this for other liquids?

This page is specifically for water. For other liquids you need to scale by specific gravity (SG): psi(liquid) = ft × 0.4335 × SG.

3. Why do some references say 2.31 ft/psi?

That’s just the inverted factor: 1 ÷ 0.4335 = 2.306… Many charts round this to 2.31 ft of water per psi.

Audit: Complete

Formula (LaTeX) + variables + units

This section shows the formulas used by the calculator engine, plus variable definitions and units.

Formula (extracted LaTeX)

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Formula (extracted text)

psi = ft H₂O × 0.4335 (at ~60°F) More generally: psi = (ft × ρ × g) ÷ 144 where ρ is water density (lb/ft³), g = 32.174 ft/s², and 144 is in² per ft².

Variables and units

No variables provided in audit spec.

Sources (authoritative):

NIST — Weights and measures — nist.gov · Accessed 2026-01-19
https://www.nist.gov/pml/weights-and-measures
NIST — SI units — nist.gov · Accessed 2026-01-19
https://www.nist.gov/pml/owm/metric-si/si-units

Changelog

Version: 0.1.0-draft
Last code update: 2026-01-19

0.1.0-draft · 2026-01-19

Initial audit spec draft generated from HTML extraction (review required).
Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
Confirm sources are authoritative and relevant to the calculator methodology.

Verified by Ugo Candido on 2026-01-19
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Formulas

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Version 0.1.0-draft

Citations

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Changelog

0.1.0-draft — 2026-01-19: Initial draft (review required).