Static elevation change in a freshwater column shows up as a pressure change. A common teaching sketch is ΔP (psi) ≈ height_ft × 0.433, which is the same freshwater idea as head_ft / 2.31 (since 1/2.31 ≈ 0.433). This page explains that sketch and gives a free browser calculator that converts both directions between elevation height (ft) and pressure change (psi). It is for learning and quick checks—not a substitute for project hydraulics, fluid density corrections, the criteria adopted by your authority having jurisdiction, or review by a licensed design professional.
How elevation pressure is used
- Decide whether you have a height (ft) to turn into a pressure change (psi), or a pressure change to turn into an equivalent freshwater height.
- For freshwater, multiply height_ft by 0.433 to get ΔP in psi, or divide psi by 0.433 to get height_ft (equivalently use head_ft / 2.31).
- Use the result only as a static elevation sketch: friction loss, fittings, pump curves, and tank freeboard still need the full project method.
- If the fluid is not freshwater (for example antifreeze solutions or other densities), do not use 0.433 / 2.31 without adjusting for specific gravity—this page assumes freshwater.
- Do not treat an elevation conversion alone as a sealed hydraulic acceptance. Net positive suction head, residual pressure, and simultaneous demands still belong in a complete calculation.
Free calculator
Educational approximation only. Freshwater factor ≈ 0.433 psi/ft (same family as 2.31 ft/psi). Nothing you enter leaves your browser. For the general pressure↔head conversion see PSI to feet of head. For pump demand vs supply sketches see the fire pump curve check or the Fire Pump & Tank Sizing workbook.
Worked example
A tank surface 40 ft above a pump datum: ΔP ≈ 40 × 0.433 = 17.32 psi of static elevation pressure before friction. Going the other way, 17.32 psi ÷ 0.433 ≈ 40 ft. The same sketch with the head factor is 40 / 2.31 ≈ 17.3 psi—always check against the adopted edition, manufacturer data, and AHJ, not this page alone.
Next steps: convert pressure and head with the free PSI to feet of head calculator, sketch pump demand with the fire pump curve check, estimate available supply with the hydrant flow test calculator or residual pressure calculator, and run full pump and tank tables in the Fire Pump & Tank Sizing workbook ($49). For sprinkler segment friction, use the Sprinkler Pipe Friction Loss workbook.