How much pressure is lost per floor?

About 4.3 psi per 10 ft of rise.

What is normal house water pressure?

40–60 psi; codes require a PRV above 80 psi.

What is feet of head?

2.31 ft of water column = 1 psi.

How do I check home water pressure?

Thread a gauge onto a hose bib or washer valve.

What pressure does a tankless heater need?

Often a minimum of 15–20 psi; check the manual.

Why is only my shower weak?

Usually a clogged showerhead or mixing valve cartridge.

Water pressure calculator

Supply pressure and height of the fixture: you get available pressure, the loss from elevation and equivalent water head.

Available pressure

2.41 bar

Available pressure at the fixture2.41 bar
Loss from elevation0.59 bar
Equivalent water head24.58 m of head

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How it's calculated (visible formula)

loss (psi) ≈ 0.433 × height (ft); available = supply − loss

Net geometric measurement, no waste.
Adjustable waste % for cuts and breakage.
Purchase rounded up to sellable units (boxes, bags, buckets, boards).

See methodology and formula versions

How to calculate it, step by step

Measure supply pressure with a gauge (or ask the utility).
Measure height between the supply and the fixture.
Elevation loss = 0.433 psi per foot.
Subtract to get available static pressure.
Compare with the appliance minimum.

Worked example: 43 psi (3 bar) supply, shower on the 3rd floor (20 ft)

Loss: 0.433 × 20 ≈ 8.7 psi (0.59 bar)
43 − 8.7 ≈ 35 psi

→ About 35 psi at the shower (static).

Common mistakes

Confusing static with flowing pressure.
No booster when the top floor drops below ~20 psi.
Skipping a PRV above 80 psi.

Pro tips

Measure with water flowing to see real dynamic pressure.
Above 80 psi, install a pressure-reducing valve.
If upper floors fall short, consider a booster pump.
Clean aerators and screens before blaming pressure.

From calculation to quote

Add labour, overhead and your margin, and generate the professional PDF.

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FAQs

How much pressure is lost per floor?: About 4.3 psi per 10 ft of rise.
What is normal house water pressure?: 40–60 psi; codes require a PRV above 80 psi.
What is feet of head?: 2.31 ft of water column = 1 psi.
How do I check home water pressure?: Thread a gauge onto a hose bib or washer valve.
What pressure does a tankless heater need?: Often a minimum of 15–20 psi; check the manual.
Why is only my shower weak?: Usually a clogged showerhead or mixing valve cartridge.

Sources and standards

Maintained by Srikanta M · Formula v1.0.0 · Verified 2026-09-10 · Updated 2026-09-10 · Limits: quantity estimation, not structural design or site supervision.