Pump Calculator
Calculate Total Dynamic Head, pump power requirements, NPSH available, specific speed, and apply affinity laws for pump selection and optimization.
Calculate Pump Specifications
Calculate total head required for pump selection
Vertical lift from source to destination
Pipe and fitting losses
Required discharge pressure as head
Usually small, often ignored
Or calculate pressure head from pressures:
Find Pump Products
Specific Speed Guide
Ns = N × √Q / H^0.75 (metric)
Higher Ns = Higher flow, lower head
Pump Calculator: Complete Guide to Pump Selection & Sizing
Our comprehensive pump calculator helps engineers, technicians, and facility managers accurately size and select pumps for any application. Whether you're calculating Total Dynamic Head (TDH), determining motor power requirements, checking NPSH available, or using the affinity laws for VFD applications, this tool provides accurate results with engineering recommendations.
Proper pump selection is critical for system efficiency, reliability, and operating costs. An undersized pump won't deliver required flow or pressure, while an oversized pump wastes energy and may cause operational problems. This calculator covers the essential calculations needed for centrifugal pump selection and performance analysis.
Key Calculations
- Total Dynamic Head (TDH) for pump selection
- Hydraulic power and motor sizing
- NPSH available to prevent cavitation
- Flow rate from pipe diameter and velocity
- Specific speed for pump type selection
- Affinity laws for VFD and impeller trimming
Applications
- Water supply and distribution systems
- Industrial process pumping
- HVAC chilled water systems
- Mining and dewatering
- Chemical transfer and dosing
- Irrigation and agriculture
Pump Calculation Formulas
Total Dynamic Head
TDH = Hs + Hf + Hp + Hv
Hs = Static head, Hf = Friction, Hp = Pressure head, Hv = Velocity head
Hydraulic Power (Metric)
P = (Q × H × ρ × g) / (3.6 × 10⁶)
P in kW, Q in m³/h, H in m, ρ in kg/m³
Hydraulic Power (Imperial)
HP = (Q × H × SG) / 3960
Q in GPM, H in ft, SG = Specific Gravity
NPSH Available
NPSHa = Pa + Hs - Pvp - Hf
Pa = Atm pressure, Pvp = Vapor pressure, Hf = Suction friction
Specific Speed
Ns = N × √Q / H^0.75
N = RPM, Q = flow rate, H = head per stage
Affinity Laws
Q₂/Q₁ = N₂/N₁
H₂/H₁ = (N₂/N₁)²
P₂/P₁ = (N₂/N₁)³
For speed changes (same for diameter ratio)
Pump Types Selection Guide
| Pump Type | Specific Speed (Ns) | Head Range | Flow Capacity | Typical Applications |
|---|---|---|---|---|
| Centrifugal (Radial) | 500 - 1,500 | 15 - 150 m | Low - Medium | General purpose, water, chemicals |
| Centrifugal (Mixed) | 1,500 - 4,000 | 5 - 50 m | Medium - High | Irrigation, cooling water |
| Centrifugal (Axial) | 4,000 - 15,000 | 1 - 15 m | Very High | Flood control, large circulation |
| Gear Pump (PD) | N/A | Up to 200 bar | Low - Medium | Oils, viscous fluids, hydraulics |
| Diaphragm (PD) | N/A | Up to 100 bar | Low | Chemicals, slurries, metering |
| Submersible | 500 - 3,000 | 10 - 300 m | Low - High | Boreholes, dewatering, sewage |