Pump Head Calculator: engineer's guide
Total dynamic head (TDH) is what the pump must overcome to deliver the design flow. It sums static lift, friction, pressure at the discharge point, and fitting losses.
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What this calculator does
The calculator sums the four components of TDH and reports the required duty point (flow + head) for pump selection.
Formulas used
- Total dynamic head:
TDH = hstatic + hfriction + hpressure + hfittings - Friction (Hazen-Williams):
hf = 10.67 × L × (Q/C)1.852 / D4.87
Variables
- hstatic = elevation gain, m or ft
- hpressure = required pressure at outlet
- hfittings = converted from equivalent length or K-factors
Worked example
Scenario: Booster pump delivering 60 GPM to the 12th floor, 40 m lift, need 20 psi at fixture, 60 m pipe with 30% fitting equivalent.
- Static: 40 m
- Discharge pressure: 20 psi ≈ 14 m
- Friction: 60 m × 1.3 fitting factor at 4 ft/100 ft ≈ 3 m
- TDH ≈ 40 + 14 + 3 = 57 m
- Pump duty: 60 GPM @ 57 m TDH; pick pump curve efficiency > 65% at duty
Common mistakes to avoid
- Missing pressure at outlet (only elevation counted)
- Under-estimating fitting equivalent length
- Not checking system curve at part-load operation
Frequently asked questions
NPSH check?
Yes — run NPSH available ≥ NPSH required + 0.6 m margin.
Variable speed?
For variable demand, VFD saves 20 to 40% energy vs constant speed.
Standards and references
ASPE Data Book Ch. 5, ANSI/HI 1.3
Related tools on this site
Open the calculator that pairs with this guide: Pump Head Calculator.
Verification note
This guide is planning support only. Final design must be verified against the applicable project specification, authority requirements, manufacturer data, and the standards cited above. Consult a licensed engineer for construction-issue calculations.