01
The purpose
What does this calculator estimate?
Add up every source of resistance your pump fights — pipe, fittings, filter, and lift — to size the right pump.
Pumps & Filtration · C3
Total Dynamic Head Calculator
Add up every source of resistance your pump fights — pipe, fittings, filter, and lift — to size the right pump.
Measure the inputsTotal dynamic head is the total resistance the pump must overcome — not just vertical lift.
Read the full resultUndersized or elbow-heavy plumbing inflates TDH and forces a bigger, thirstier pump.
Check the boundaryBigger pipe lowers friction sharply — going from 1.5" to 2" can cut friction loss in half.
Useful forPumps & FiltrationPlanningComparisonVerification
Live calculation
System resistance
✓ Checked May 2026
Enter pipe runs, fittings, lift, and filter type.
Calculated result
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Enter the required values to calculate.
Enter the known values. Let the engine handle the calculation.
✓ Formula checked↻ Live result○ No account needed
Planning estimate only. Confirm product labels, equipment specifications, qualified-professional advice and local requirements before acting.
The result, explained
Use the Total Dynamic Head Calculator result with context.
Add up every source of resistance your pump fights — pipe, fittings, filter, and lift — to size the right pump.
02
The tool
What information does it use?
- Suction pipe size: Diameter of the line into the pump.
- Suction pipe length: enter a measured or verified value
- Discharge pipe size: Diameter of the line after the pump.
- Discharge pipe length: enter a measured or verified value
- Static head (lift): Vertical rise from water to the pump/equipment.
- Flow rate: Design GPM.
- Suction elbows: Count of 90° elbows before the pump.
- Discharge elbows: Count of 90° elbows after the pump.
- Filter type: Each filter adds its own head loss.
03
The method
How to use this calculator
- Suction pipe sizeDiameter of the line into the pump.
- Suction pipe lengthEnter the value you can verify.
- Discharge pipe sizeDiameter of the line after the pump.
- Discharge pipe lengthEnter the value you can verify.
- Static head (lift)Vertical rise from water to the pump/equipment.
- Flow rateDesign GPM.
- Suction elbowsCount of 90° elbows before the pump.
- Discharge elbowsCount of 90° elbows after the pump.
- Filter typeEach filter adds its own head loss.
04
The relationship
The formula in plain English
TDH = static head + pipe friction + fitting loss + filter head loss
Pipe friction uses Hazen-Williams (C=150 for PVC). Each elbow adds equivalent pipe length.05
Worked through
A worked example: 60 GPM, 2" pipe, 30 ft suction + 40 ft discharge, 4 ft lift, sand filter
- Pipe friction (70 ft of 2" at ~4/100 ft) ≈ 2.8 ft
- Fittings (5 elbows × ~4.5 ft equiv) ≈ 1.0 ft
- Static 4 ft + filter (24" sand) 8 ft → TDH ≈ 15.8 ft
| Pipe size | Friction loss /100 ft | Velocity | Verdict |
|---|---|---|---|
| 1.5 inch | ~14 ft | 9.4 fps | Too restrictive |
| 2 inch | ~4 ft | 5.7 fps | Good |
| 2.5 inch | ~1.7 ft | 4.0 fps | Excellent |
| 3 inch | ~0.7 ft | 2.6 fps | Very low loss |
06
Why it matters
How the result supports the next decision
Total dynamic head is the total resistance the pump must overcome — not just vertical lift.
Undersized or elbow-heavy plumbing inflates TDH and forces a bigger, thirstier pump.
07
Good inputs
Improve the estimate before relying on it
- Total dynamic head is the total resistance the pump must overcome — not just vertical lift.
- Undersized or elbow-heavy plumbing inflates TDH and forces a bigger, thirstier pump.
- Bigger pipe lowers friction sharply — going from 1.5" to 2" can cut friction loss in half.
- Read the pump's flow curve at your TDH, not its headline 'max flow' number.
- Dirty filters raise head loss over time; size with a margin above the clean-filter figure.
08
The boundary
How to interpret the result
Measurements, equipment specifications, site conditions and local requirements can change the practical result.
The engine reports invalid inputs and safety warnings beside the result. Resolve those messages before using the estimate.
09
Before acting
What should override this estimate?
- Measured site conditions and current test results
- Product labels and manufacturer specifications
- Qualified-professional advice and applicable local codes
10
Common questions
Frequently asked questions
What is total dynamic head?
Total dynamic head (TDH) is the total resistance, expressed in feet, that a pump must overcome to move water through your whole system. It combines the static lift from water level to equipment, friction in the pipes, losses through elbows and valves, and the resistance of the filter. Pumps are matched to a system by their flow at a given TDH.
Why do I need to know TDH to size a pump?
A pump's flow isn't a single number — it drops as resistance rises. The flow curve shows GPM at each head value. If you size a pump by its 'max flow' instead of its flow at your actual TDH, you'll get far less water movement than expected. TDH tells you where on the curve your system really sits.
How do elbows and fittings affect TDH?
Each fitting adds friction equivalent to a length of straight pipe — a 2-inch 90° elbow adds roughly 4.5 feet of equivalent pipe. A plumbing run with many tight elbows can carry significantly more head loss than its straight length suggests, which is why minimizing sharp turns matters.
How does pipe size change TDH?
Larger pipe dramatically reduces friction loss because resistance falls steeply with diameter. Upgrading from 1.5-inch to 2-inch pipe can roughly halve friction loss at the same flow. Oversized plumbing lets you run a smaller, more efficient pump, which is why builders favor 2-inch and larger lines.
What is a typical TDH for a residential pool?
Most residential pools land between 30 and 60 feet of total dynamic head, depending on pipe size, run length, fitting count, and filter type. Spas and pools with long equipment runs or heaters can run higher. Calculating it precisely avoids guessing and oversizing.
What is a good TDH for a pool pump?
Most residential systems fall between 30 and 60 feet of head; calculate yours to size the pump accurately.
Does a longer pipe run increase TDH?
Yes — friction loss scales with pipe length, so longer runs and more fittings raise total dynamic head.
How do I lower my pool's TDH?
Use larger pipe, reduce elbows and sharp turns, and keep the filter clean — all cut head loss.
Primary sources
Use the result with current guidance.
These official references support safe planning context. Product labels, local requirements and qualified-professional advice take priority over a general calculator estimate.