Softener sizing calculator
A practical residential estimate of resin volume and operating parameters based on hardness and water usage.
People
Water hardness (°dH)
Water use per person (L/day)
Suggested resin volume
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Regeneration every
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Salt per regeneration
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Estimated monthly salt use
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Uses a practical residential working capacity of about 2.8 m3 x °dH per liter of resin at a typical salt dose. Treat the result as a starting point for equipment selection.

Softener sizing calculator provides a quick estimate of resin volume and a typical regeneration interval based on water hardness and usage. It helps you check whether a given model is likely to be sufficient and explains how hardness affects salt consumption and user comfort.

Results are approximate. Final sizing should consider water analysis (e.g., iron, manganese), required peak flow, valve settings and the preferred regeneration frequency.

FAQ - Softener sizing

What inputs do I need to size a softener?

Water hardness, number of users and estimated water usage. Peak flow demand and installation space also matter.

How can I measure water hardness?

Use a drop test, test strips, or utility data. Ideally, confirm utility values with an on-site test.

What is regeneration and how often should it happen?

Regeneration restores resin capacity using brine. Too frequent wastes salt, too infrequent reduces performance. Many homes target several to a dozen days.

What affects salt consumption?

Hardness, water usage, resin volume and salt dose settings. Different valves may offer efficiency modes.

Does a softener remove iron or manganese?

Only to a limited extent. Higher iron/manganese levels usually require dedicated media or a multifunction system.

Do I need a bypass?

Yes, a bypass simplifies service and allows water supply during maintenance. Many units include a bypass valve.

Why is the water still hard after installation?

Common causes include incorrect settings, wrong hardness value in the valve, exhausted resin, installation issues or bypass left open.