Water Pressure Calculator

Calculate static water pressure from head height.

Mason ReidFounder and Lead Estimator at MeasureThen

Last updated 2026-08-21

What Is a Water Pressure Calculator?

A water pressure calculator converts the height of a water column, called head, into pressure in pounds per square inch. Fresh water adds about 0.433 psi for every foot of vertical rise. Homeowners use it to estimate pressure at the bottom of a storage tank, a well riser, or a vertical supply pipe, and to understand why a fixture on an upper floor has lower pressure than one near the main.

How It Works

Pressure (psi) = Fluid density × Head height ÷ 144. Water: ~0.433 psi per ft.

Example

A 10 ft water column produces about 4.33 psi.

How to Calculate

Measure the vertical height of the water column in feet. This is the head, the straight vertical distance from the water surface to the point you care about.
Enter the head height into the tool. For a water tank that sits 20 ft above the faucet, the head is 20 ft.
Read the result. The tool multiplies the head by 0.433 psi per foot. A 20 ft column produces about 8.66 psi.
Subtract for elevation loss on upper floors. Each 10 ft of height above the main drops the available pressure by roughly 4.33 psi.
Add the result to any pump pressure. For a well system, add the calculated static head pressure to the pump cut in pressure to find the total at the fixture.

PSI produced by water head height

Head height	Pressure	Common use
10 ft	4.33 psi	One floor above the main
20 ft	8.66 psi	Two floors above the main
30 ft	13.0 psi	Roof storage tank
50 ft	21.7 psi	Tall riser or elevated tank
100 ft	43.3 psi	Municipal water tower

Sources

Frequently Asked Questions

What is static pressure?

The pressure from the weight of the water column alone, without any pump or flow.

How much does a foot of water weigh in psi?

Fresh water adds about 0.433 psi for every foot of head.

Can I leave density blank?

Yes — it defaults to fresh water at 62.4 lb/ft³.

Mason ReidFounder and Lead Estimator at MeasureThen

Mason Reid founded MeasureThen after two decades of hands-on work in construction and estimating. Across residential and light commercial projects, he sized concrete pours, framed walls, hung drywall, and priced out roofing, fencing, and deck work — learning the exact math that every job depends on. At MeasureThen he writes the formulas, checks every calculator against real-world assumptions, and makes sure each one is simple enough for a homeowner to trust and a contractor to use. When he is not measuring twice, he is helping projects stay on budget.

Every MeasureThen calculator uses simple, transparent formulas and standard industry assumptions drawn from common construction practice. We show the math behind each result and include worked examples so you can follow along and double-check the numbers. Results are estimates: materials, labor, and pricing vary by region and market, so always confirm important figures with a licensed professional and your local building codes.