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Pool Pump Affinity Law Calculator

Estimate changes in flow, head, and power when pump speed changes.

Estimated result:
Planning estimate: Confirm equipment specifications, performance tables, warranties, local requirements, and site conditions before purchasing or changing equipment.

How This Calculator Works

Enter realistic values from your pool, equipment labels, utility bill, or written estimate. Change an assumption to see how it affects the result.

What Matters Most

For the same pump and system under ideal conditions, flow changes with speed, head with speed squared, and power with speed cubed.

Real systems deviate because static head, valve positions, equipment limits, motor efficiency, minimum flow requirements, and control behavior do not scale perfectly.

Common Mistakes

  • Using advertised maximums instead of performance at actual operating conditions.
  • Ignoring plumbing, filter, heater, sanitizer, automation, or electrical limits.
  • Rounding inputs before the final result.
  • Treating a planning estimate as a substitute for manufacturer instructions.

Frequently Asked Questions

Should I use measured values?

Yes. Measured flow, watts, pressure, dimensions, and current pricing usually improve the estimate.

Is the largest option always best?

No. Equipment should meet the required range without violating minimum flow, maximum flow, velocity, electrical, space, or compatibility limits.

Pool Gal Pro Tip 💦

Write down the clean, working baseline when equipment is new. Future-you will look brilliant when troubleshooting season arrives.