Garden & Outdoor calculator
What Garden Pump Size Do I Need?
Calculate garden pump duty point using required flow rate, vertical lift, and estimated pipe/fitting head loss.
Enter your measurements
Use this minimum-capacity calculation when you need to answer “what garden pump size do i need?” Enter required flow rate, vertical lift, and estimated pipe/fitting head loss and the tool returns garden pump duty point using the rule defined for this exact use case.
- Required flow rate — Required
- Vertical lift — Required
- Estimated pipe/fitting head loss — Required
- Required outlet pressure head — Required
Garden pump duty point
Enter the measurements above to calculate garden pump duty point.
How the calculation works
V17 calculation: totalDynamicHead=staticLift+frictionHead+pressureHead; dutyFlow=requiredFlow. The result is reported as Garden pump duty point.
Worked example
Example: Required flow rate = 0.8 L/s; Vertical lift = 50 cm; Estimated pipe/fitting head loss = 50 cm; Required outlet pressure head = 50 cm. Result: Duty Flow = 0.8 L/s; Total Dynamic Head = 150 cm.
Before you decide
Use measured dimensions rather than nominal labels. This page calculates the stated geometry or quantity only; product-specific construction or installation details can still affect the final choice. For what garden pump size do i need, the limiting result on this page is garden pump duty point.
The calculator returns the required flow and total dynamic head only. A chosen pump must subsequently be checked against its own published performance curve.
Frequently asked questions
What does the Garden Pump Size calculator tell me?
It returns garden pump duty point from the measurements entered on this page. The calculation is specific to garden pump size, so the result should be compared with the exact product or specification you are considering.
Which measurements should I take for garden pump size?
Measure required flow rate, vertical lift, estimated pipe/fitting head loss, required outlet pressure head. Use clear, usable dimensions rather than nominal room or product labels.
Should I round the garden pump duty point?
Keep the calculated value for comparison, then choose a real product that meets or stays within the returned garden pump duty point while allowing for the clearances, tolerances or ratings shown by its manufacturer.