What Size Water Softener Do I Need? (Sizing Guide)
Number copied. Text it from your phone: 443-277-2204.
Most homes need the 48,000 grain softener. Five or more people, or three or more on water over 15 grains, need the 64,000 or 80,000. Put your hardness and the number of people in the house into the calculator below and it shows you your size, what it costs and about how often it will regenerate. It runs the sizing formula plus the rules I give people who call me with their water test.
Water softener size calculator
No hardness number yet? On city water, your utility's water quality report may list it, and the city water test measures it at your tap. On a well, the certified well water test gives you hardness and iron from one sample.
Quick Answer
Water softener sizing comes down to one formula: (Water Hardness + Iron PPM x 5) x Daily Gallons x Days Between Regeneration = Required Grain Capacity.
- Daily water use. Count about 75 gallons a person a day, so a family of four uses about 300. See how to work out the size yourself.
- Your water hardness in grains. If your report gives mg/L or ppm, divide by 17.1. On a well, add 5 grains for every 1 ppm of iron.
- A size that lasts a week. Multiply by 7 days and pick the size that holds that much on a salt-saving setting. A softener holds less than the grain number on its label, so size it on what it really holds.
- Size for your household. One or two people: the 48,000. Three or four people: the 48,000 up to 15 grains, then the 64,000 or 80,000. Five or more: the 64,000 or 80,000. See the size chart.
The four Fleck 5600SXT water softeners run from $1,495 to $2,495, and the 48,000 grain ($1,995) is the one most homes get.
What's in This Guide
Softener size chart by household
Five or more people need the 64,000 grain or bigger. Find your household, then your hardness.
| People in the house | Up to 10 grains of hardness | 11 to 15 grains of hardness | 16 to 20 grains of hardness | 21 to 30 grains of hardness |
|---|---|---|---|---|
| 1 or 2 people | 48,000 grain | 48,000 grain | 48,000 grain | 48,000 grain |
| 3 people | 48,000 grain | 48,000 grain | 64,000 grain | 64,000 grain |
| 4 people | 48,000 grain | 48,000 grain | 64,000 grain | 80,000 grain |
| 5 or 6 people | 64,000 grain | 64,000 grain | 80,000 grain | 80,000 grain |
Each size is for the top of its hardness range, with no iron and no pool or hot tub. On a well with iron under 1 ppm, add 5 grains for every 1 ppm before you look it up. Over 30 grains, or seven or more people, use the calculator or text me your test.
The chart and the calculator start at the 48,000. The 32,000 grain ($1,495) covers one to three people on water up to about 15 grains by the math, and the 48,000 costs $500 more. I still start people at the 48,000: if your water use goes up, a 32,000 regenerates more often and uses more salt.
One or two people get the 48,000 even on hard water. A caller in Minnesota had 27 grains, lived alone and had three bathrooms. I told the caller the 48,000 would "give you plenty of capacity," or the caller could go a little bigger, to the 64,000.
Text me your numbers for a size
Send me your hardness, your iron and how many people live in the house. I will tell you which size, and whether you need a softener at all.
Call 800-460-5810 or text Aidan at 443-277-2204.How to work out the size yourself
Grain capacity is how many grains of hardness the resin takes out before the softener has to regenerate. Pick a size that lasts a week between regenerations.
- People times 75 gallons. The Water Quality Association's current estimate is 75 gallons a person a day. A family of four is about 300 gallons.
- Your hardness in grains per gallon. Lab reports often give hardness in mg/L, which is the same as ppm. Divide by 17.1 to get grains: 257 mg/L is about 15 grains.
- Add 5 grains for each 1 ppm of iron. Iron uses up the resin faster, so it counts as extra hardness. I count 5. One supplier's sizing sheet uses 4, and the Water Quality Association says 3 is typical, so counting 5 sizes you up, never down.
- Multiply by 7 days. That is the capacity for about a week between regenerations. The 48,000 in my house regenerates once a week to once every two weeks.
- Pick the size that holds a week. Use what each size holds on a salt-saving setting, in the table below.
In my video I take 10 grains of hardness and 1 ppm of iron: that is 15 grains to account for, and I recommend the 48,000. For a family of four the math runs 300 gallons x 15 grains = 4,500 grains a day, or 31,500 in a week. The 48,000 holds 36,000 on a salt-saving setting, so it covers that week and regenerates about every 8 days.
The spec sheet for these softeners rates each one below its label, even on full salt. The 48,000 holds about 45,000 grains on full salt and 36,000 on a salt-saving setting.
| Size | Resin (the beads) in the tank | Grains it holds when saving salt | Grains it holds on full salt | Water flow | Price |
|---|---|---|---|---|---|
| 32,000 grain | 1.0 cubic foot | 24,000 grains | 30,000 grains | 9 gallons a minute | $1,495 |
| 48,000 grain | 1.5 cubic feet | 36,000 grains | 45,000 grains | 12 gallons a minute | $1,995 |
| 64,000 grain | 2.0 cubic feet | 48,000 grains | 60,000 grains | 13 gallons a minute | $2,195 |
| 80,000 grain | 2.5 cubic feet | 60,000 grains | 75,000 grains | 15 gallons a minute | $2,495 |
I walk through these same examples, and when to size up, in this video:
When to go one size bigger
Go one size bigger for a big family, hard water or a pool.
- Five or more people. "If you have five people and three bathrooms, I would definitely recommend the 64,000 grain unit." It is a larger tank, so when several showers run you do not get that big pressure drop. A caller in Los Angeles with five adults asked the same thing, and I told the caller that at 15 grains, "you'd put a 64,000 grain in there."
- A family on hard water. With 25 grains and four or five people, go with the 64,000 or even the 80,000 for more capacity, less salt and less water down the drain. A caller on 32-grain water had a local company recommending a 48,000, and I said, "A 48,000 grain's too small. You need a 64,000 grain."
- A pool, hot tub or irrigation. If one runs on softened water all year, go a size bigger than the math says.
In the video I count bathrooms too. Bathrooms decide how much water runs at once, which is flow, not capacity: the spec sheet rates the 48,000 at 12 gallons a minute and the 80,000 at 15. A caller with 12 people and 10 bathrooms asked whether the 80,000 was big enough. I told the caller, "We have it in houses with 7 full bathrooms," and that going bigger is "not necessary 'cause they're not using water all the time."
Iron in well water changes the size
Each 1 ppm of iron counts as 5 more grains of hardness. At 1 ppm or more, put an iron filter ahead of the softener. A softener can take out a little iron, but as I tell callers, "A lot of people try to take iron out with a softener. It shortens the life of the softener. Eventually, the resin will fail."
Under 1 ppm, size the softener on your hardness plus the iron. At 1 ppm or more, the iron filter takes the iron out first, "so it's zero before it hits the softener," and you size the softener on your hardness alone. The iron filter and water softener packages pair the two, and iron filter vs water softener explains which one does what. If you do not have an iron number yet, the certified well water test reports iron and hardness from one sample.
An acid neutralizer makes your water harder
An acid neutralizer adds about 3 to 6 grains of hardness. Size the softener on the water after the neutralizer. What I tell people is to put the neutralizer in, give it a week or two, and then retest the hardness. If it is above 7 grains, consider a softener.
One buyer wrote that his well started at pH 5.4 and went to 8.3 after the neutralizer: "I was OK with the change, but it did change my water to hard." His hardness came out at about 8.7 grains, and he added a softener. Verified buyer James H., March 2020.
The neutralizer goes first and the softener second. Acid neutralizer and water softener covers the pair, and the acid neutralizer and water softener packages are sized to work together.
Do you need a twin tank softener?
Most homes only need one tank. A twin tank keeps soft water coming while one tank regenerates. Only one tank works at a time, so it softens the same amount between regenerations as a single tank of that size. One valve runs both tanks, but the water does not go through them in series. When one tank regenerates at 2:00 AM, the valve switches you over to the other. As I put it to one caller, "If it's a 64K in one tank, it's 64K in the other tank... It's just so you never run out of soft water."
That matters when someone uses water in the middle of the night, or gets up early for a shower, on very hard water where any hard water bleeding through would show. Pick the twin by the same table: its grain number is what each tank holds.
| Twin tank | Resin (the beads) in each tank | Price |
|---|---|---|
| Fleck 9100SXT 64,000 grain twin tank | 2.0 cubic feet | $2,695 |
| Fleck 9100SXT 80,000 grain twin tank | 2.5 cubic feet | $2,995 |
What happens inside a tank while it regenerates is in the guide to water softener regeneration.
Frequently asked questions
What size water softener do I need for a family of 4?
For a family of four with average hardness (10 to 15 GPG) and no iron, a 48,000 grain softener is the standard recommendation. If your hardness is above 15 GPG, counting 5 grains for each 1 ppm of iron, size up to a 64,000 grain system, and above about 22 grains to the 80,000.
What size water softener do I need for a family of 2?
Two people with moderate hardness (under 15 GPG) can use a 32,000 grain softener. I still put two-person homes on the 48,000 ($1,995); the reason is under the size chart.
How many grains should my water softener be?
Enough for about a week of your water on a salt-saving setting. Grain capacity is how many grains of hardness the resin takes out before it regenerates. For most homes that is the 48,000 grain; the formula above works it out for yours.
What happens if my water softener is too big?
It regenerates less often, and the valve still regenerates after a set number of days even with capacity left. You don't really need the biggest water softener, you just need the right one; the 48,000 and 64,000 give almost any household plenty of capacity. The real downside is price: the 80,000 costs $500 more than the 48,000.
How long does a 40 lb bag of salt last in a water softener?
In my house the 48,000 goes through one 40-pound bag every 30 to 45 days. How fast yours goes depends on your hardness and how much water you use. The guide to water softener regeneration covers the salt each cycle uses.
Is a 30000 grain water softener enough?
For one or two people with moderate hardness, yes. For a family of four at 15 grains it is tight: that family takes out about 4,500 grains a day, so a 30,000 grain softener would regenerate about every 6 or 7 days even at its full label rating, and more often on a salt-saving setting. The smallest size we sell is the 32,000 grain ($1,495), and I put most homes on the 48,000.
Aidan Walsh
Co-owner & Residential Water Treatment Specialist, Mid Atlantic WaterAidan Walsh has spent 32 years in residential water treatment, the first stretch of it installing and servicing well systems before Mid Atlantic Water became an online supplier. Mid Atlantic Water is a family company; every recommendation on this site is based on what actually failed in the field and what fixed it. If you have a question this page did not answer, call 800-460-5810 or text him at 443-277-2204.
Aidan answers calls and texts 8 AM to 5 PM Eastern, every day.Number copied. Text it from your phone: 443-277-2204.