Free Calculator · Published October 2026
Softener Sodium Calculator: Sodium Added per Grain
Turn hardness into the sodium a sodium-chloride softener adds. Leave the lab sodium blank if you only want the added part.
Built by SubcontractorHub — the software plumbing contractors use to quote, finance, and run every job.
Book a DemoA Softener Sodium Calculator Starts from Hardness
This softener sodium calculator uses the factor in NDSU Extension WQ1031. Salt pounds per regeneration are the salt dose calculator. A year of bags is the water softener salt cost calculator.
Compensated hardness if iron and manganese are in the number the valve uses. Say which.
mg/L is divided by 17 to reach grains. That is the NDSU factor, not 17.1.
From the lab, not from a taste. Blank means the tool reports only what the softener adds.
Important: All calculator results are ballpark estimates
All calculations are estimates based on historical information and should be verified by the user. This tool is provided as a free service for planning purposes only and is not a substitute for a professional assessment, a supplier quote, or applicable local code requirements.
What the Softener Sodium Calculator Is Using
Eight milligrams per liter per grain
WQ1031 says a water softener adds about 8 mg/L of sodium for each grain of hardness removed. Ten grains is about 80 mg/L added. Fifteen grains is about 120 mg/L added. The word "about" is in the extension page. This tool multiplies by 8 exactly so the note on the job matches the arithmetic, and it still calls the result an estimate. It does not substitute a stoichiometric 7.87, which this page did not take from WQ1031.
Seventeen milligrams per liter is one grain
If the lab prints hardness as mg/L of calcium carbonate, divide by 17 to get grains, then multiply by 8. One hundred seventy mg/L is 10 grains and about 80 mg/L of sodium added. The water hardness converter uses 17.1 mg/L per grain. Say which factor you used when you write the customer record. Do not mix them in one sentence and call them the same number.
Worked examples
Same math as the form. The third column is blank when existing sodium was left blank.
| Case | Grains | Added | With existing |
|---|---|---|---|
| 10 gpg, no existing sodium | 10 | 80 mg/L | — |
| 170 mg/L as CaCO3, no existing sodium | 10 | 80 mg/L | — |
| 15 gpg plus 20 mg/L already in the water | 15 | 120 mg/L | 140 mg/L |
Sodium chloride only
The exchange is sodium for calcium and magnesium. Potassium chloride is a different regenerant. WQ1031 says it takes about 10 percent more salt by weight and costs more. It does not give a sodium milligrams-per-liter figure for potassium, and this page will not invent one. Salt choice itself is the water softener salt types guide. If the customer asks whether softened water is fine to drink, start with is soft water safe to drink and keep this number as the estimate, not as advice.
A kitchen tap can stay off the softener
WQ1031 describes plumbing the cold kitchen faucet before the softener so drinking and cooking water are not the softened line. That is a bypass of one tap, not a claim that sodium is harmless or harmful. A person who limits sodium should talk to a clinician. The dealer's job is to show the estimated addition and the plumbing option, then write down what the customer chose. Chloride already in the well is a different question. See chloride in well water. A softener does not take chloride out.
What to write on the job ticket
Hardness, the unit, whether iron was compensated into that hardness, the grains you used, sodium added, and existing sodium if the lab had it. Note sodium chloride versus potassium chloride. A water treatment dealer who saves that note can answer the sodium question on the next visit without redoing the arithmetic from memory. SubcontractorHub keeps the note on the customer record with the test and the equipment.
Frequently Asked Questions
What does a softener sodium calculator estimate?
It estimates sodium added when a softener removes hardness and is regenerated with sodium chloride. North Dakota State University Extension WQ1031 states that a softener adds about 8 milligrams per liter of sodium for each grain of hardness removed, and that one grain per gallon equals 17 milligrams per liter. Optional existing sodium is added on top. It is not a medical recommendation and it does not convert potassium chloride into a sodium number.
Does a water softener remove sodium?
A cation softener regenerated with sodium chloride exchanges sodium for calcium and magnesium. The hardness ions stay on the resin until regeneration. Sodium leaves with the treated water. That is why the kitchen tap can taste slightly salty on a high-hardness well even when the softener is working. Chloride that was already in the well is a separate ion. This calculator does not remove or add chloride.
What if the softener uses potassium chloride?
This page is sodium chloride only. NDSU notes that potassium chloride uses about 10 percent more salt by weight and costs more. It does not publish a milligrams-per-liter sodium figure for potassium, because potassium is not sodium. Do not type a potassium result into the existing-sodium field and treat the total as sodium.
Why might this differ from the hardness converter?
This calculator uses 17 milligrams per liter per grain, the factor NDSU prints in WQ1031. The water hardness converter on this site uses 17.1. A lab report in milligrams per liter will not land on the identical grain on both pages. Use one factor for the note you leave on the job, and say which page you used.
Is the sodium number a drinking-water limit?
No. The result is an estimate of sodium added by softening, plus any sodium you already typed. It is not a diagnosis and not a public-water maximum. A person on a sodium-restricted diet should ask a clinician, and a dealer can offer a kitchen-tap bypass so drinking water is not the softened line. NDSU describes that bypass as an option.
Save the Sodium Note With the Test
Hardness, the regenerant, and the milligrams you estimated belong on the job, next to the lab page.
Get a Free DemoAll calculations are estimates based on historical information and should be verified by the user. This tool is provided as a free service for planning purposes only and is not a substitute for a professional assessment, a supplier quote, or applicable local code requirements. It does not give medical advice, and it does not convert potassium chloride into sodium.