Suction Head to PSI Converter
Suction head is the height of liquid column available at the pump inlet. Converting suction head to pressure tells you the available inlet pressure — a critical parameter for Net...
Formula
Source: Engineering Toolbox, Hydraulic Institute Standards | Last reviewed: June 8, 2026
Examples
10 ft
= 4.33 psi
- SG = 1
10 ft water column = 4.33 psi suction pressure
20 ft
= 6.5 psi
- SG = 0.75
20 ft of naphtha (SG 0.75) = 6.5 psi
5 ft
= 2.6 psi
- SG = 1.2
5 ft brine column (SG 1.2)
Quick Reference Table
| ft suction head | psi inlet pressure |
|---|---|
| 5 | 2.17 |
| 10 | 4.33 |
| 15 | 6.5 |
| 20 | 8.66 |
| 30 | 13 |
| 50 | 21.65 |
Where is this used?
Tank-to-pump elevation design: sizing the minimum liquid level above a pump to prevent cavitation.
Hydrocarbon transfer: verifying adequate suction pressure for volatile liquids with high vapor pressure.
Frequently Asked Questions
What is the minimum suction head needed?
The minimum suction head must exceed the pump's NPSH requirement (NPSHr) plus the fluid's vapor pressure head plus a safety margin (typically 3 ft for water). If available suction head is too low, the pump will cavitate.
How does suction lift differ from suction head?
Suction head means the liquid level is above the pump centerline (flooded suction). Suction lift means the pump must pull liquid up from below. Suction lift is negative head and limits the maximum lift to about 25-30 ft for water at sea level.
Does fluid temperature matter for suction head?
Yes, critically. Hot liquids have higher vapor pressure, reducing the effective suction head. Water at 200°F has a vapor pressure of 11.5 psia, meaning you need significantly more suction head to prevent cavitation than with cold water.
Reviewed for accuracy
· Last reviewed: June 8, 2026
All calculations are for reference only. Always verify with manufacturer data and a qualified engineer for critical applications. Learn about our editorial process.