Water Softener Capacity & Regeneration Calculator

Compare capacity against your household hardness load

A tank size or rental payment does not tell you how frequently a softener will regenerate.
Water usage, measured hardness and the selected salt setting determine how much water can be treated between regenerations.
This calculator compares two candidates using daily hardness load and verified working capacity, then estimates intervals, annual salt, regeneration water, discharge and consumable costs.

Use the result to review a desired interval and prepare questions for the supplier.
It is not a brand ranking or a recommendation to buy the largest unit.
Capital and rental costs belong in a separate purchase comparison; check whether a maintenance contract already includes the consumables shown here.
The physical model is not country-specific, but this interface consistently uses KRW for entered prices and costs.

Start with the right water volume and hardness

The calculator does not assign daily usage from family size.
Shower habits, laundry connections and the treated plumbing scope can change the fraction passing through the unit.
Leave an unknown measurement blank instead of entering zero to obtain a result.

Resin volume is not working capacity

Working capacity means documented hardness removal at a particular salt dose and operating condition.
Liters of resin are a different quantity.
Combining an advertised maximum capacity with a low-salt consumption figure can produce an interval that does not correspond to any real operating setting.

Choose g or mg for capacity: 1,000 g equals 1,000,000 mg.
Changing the selector changes the interpretation of the entered number and does not convert it automatically.
If a quoted capacity already deducts a controller reserve, check whether an additional reserve would count the same allowance twice.

Hardness load, treated volume and regeneration formulas

Verified zero usage or zero hardness gives zero hardness load.
The interval is then marked not applicable instead of infinity, with zero load-based annual cycles and consumption.
Timer, forced or hygiene regeneration may still be required and remains outside this load-only model.

Step-by-step use and missing information

1. Enter daily service water and total hardness from records, noting the measurement date.
2. Label A and B as two models or two documented settings of one model.
3. Enter paired capacity and salt dose, then choose a reserve.
4. Check total regeneration supply, discharge and brine volumes; add actual salt and incremental water/sewer prices.
5. Review capacity margins, annual quantities and cost differences, then save a TXT worksheet.
6. Ask the supplier to verify operating and installation conditions; optionally mark your own confirmation afterward.

Blank means unknown; zero means a verified zero.
A missing capacity for A does not prevent calculation for B.
Intervals can remain available while prices or consumables are missing, but the corresponding costs are withheld.
Enter zero for a genuinely included or free item only after checking its scope.

Inputs accept commas and decimals and preserve an empty field while editing.
Displayed input limits are software support limits, not equipment operating limits.
Capacity and target days must be positive; reserve must be supplied for capacity-based calculations.
The initial 7-day target and 0% reserve are editable planning assumptions, not recommended settings.

Worked example: 500 L/day at 200 mg/L

This is a fictional example, not a market average or guaranteed product performance.
500 L/day × 200 mg/L gives 100,000 mg/day.
For A, 1,000 g equals 1,000,000 mg; a 0% reserve gives 5,000 L of treated volume and a 10-day interval.

Assumed prices are KRW 1,000/kg for salt, KRW 1,000/m³ for water and KRW 500/m³ for sewer.
A costs KRW 2,150 per cycle and B costs KRW 2,680 per cycle.
Although B costs more each time, its annual equivalent cost is about KRW 13,261.67 lower.
Equipment and installation prices are excluded, so this is not a purchase recommendation.

Interpret the target interval and reserve

Reserve is a user assumption, not a statutory or universal recommended percentage.
Agree on it with the supplier using demand variability and controller behavior.
An exact match gives a zero margin; target checks use unrounded values even when the display is rounded.
A blank target leaves interval calculations available while withholding required capacity and the target check.

An interval below one day calls for a separate review of hourly demand and water supply during regeneration.
A very long interval does not authorize unlimited time between regenerations.
Maximum waiting days and scheduled regeneration can cause actual cycles to exceed this load-based estimate.

Avoid double counting salt, brine and water

Per-cycle cost is salt kg × KRW/kg, plus total water L ÷ 1,000 × water KRW/m³, plus discharge L ÷ 1,000 × sewer KRW/m³.
Each quantity and price must be known before the combined cost is reported.
Discharge is a separate input because its applicable volume may differ from water supply.

A bill total divided by water usage can include fixed charges.
Enter the price applicable to additional usage instead.
If the water field already includes sewer charges, set sewer price to zero to avoid duplication.
Keep taxes, salt delivery and discounts consistent across candidates.

Use the comparison in purchase and rental discussions

Scope and conditions to verify

• Check flow, pressure and target residual hardness against the quoted capacity.
• Ask whether operating reserve or resin aging is already included.
• Obtain the paired salt setting and the scope of total supply and discharge measurements.
• Confirm forced or hygiene regeneration, servicing and extended-absence instructions.
• Add equipment, installation, electricity, resin replacement, repair and rental costs separately.

More displayed decimals do not imply better field accuracy.
Water-quality and demand variability can matter much more than rounding.
Update assumptions against actual operating records.

Frequently asked questions