Water Hardness Calculator
Convert your water hardness between ppm (mg/L) and grains per gallon (gpg), and see how hard your water is — then get the right softener.
How water hardness is measured
1 grain per gallon (gpg) = 17.1 ppm (mg/L). Most US homes fall between 3 and 20 gpg. Above 7 gpg you'll see scale, spotting and dry skin — a softener pays for itself in appliance life.
Frequently asked questions
How do I convert ppm to grains per gallon?
Divide ppm by 17.1. For example, 171 ppm = 10 gpg. Our calculator does it instantly both ways.
What is considered hard water?
Above about 7 gpg (120 ppm) is hard, and above 10.5 gpg (180 ppm) is very hard. At those levels a water softener is strongly recommended.
How do I find my water hardness?
Check your municipal water report, use a test strip, or send a well sample to a lab. Then enter the number here to convert and classify it.
Understanding Water Hardness Levels
Water hardness is typically classified into categories that help homeowners understand their water quality. Soft water has a hardness level of 0-3 gpg (0-51 ppm), moderately hard water ranges from 4-7 gpg (68-120 ppm), hard water is defined as 8-10.5 gpg (136-180 ppm), and very hard water exceeds 10.5 gpg (180 ppm). Knowing which range your water falls into can help you take appropriate action to mitigate potential issues.
Assessing Your Home's Water Source
Before investing in a water softener, it’s essential to determine the source of your water supply. Municipal water systems usually provide a water quality report, which can guide you in understanding your water's hardness. If you rely on a private well, consider using a water testing kit or sending samples to a certified laboratory to get an accurate measurement of hardness and other contaminants present in the water. Understanding these factors will better inform your choice of equipment.
Choosing the Right Water Softener Size
When selecting a water softener, size is crucial. The size of the softener you need will depend on the hardness level of your water and your household's water usage. A common method to estimate the appropriate size is to multiply the hardness (in grains per gallon) by your daily water usage (in gallons). This will give you a rough estimate of the capacity you'll need. Always consult the manufacturer’s guidelines for specifics on sizing based on your water hardness and usage levels.
Common Missteps in Water Softener Installation
Proper installation is vital for the effective operation of your water softener. One common mistake is placing the unit in an area with extreme temperatures, such as garages or basements that are prone to freezing. Ensure that the installation area is well-drained and has easy access to your plumbing system. Another frequent error is bypassing the pre-filter stage, which can lead to premature wear of the softener. Always follow the installation guidelines provided by the manufacturer, and consider hiring a professional if you're unsure.
Routine Maintenance Practices for Water Softeners
Maintaining your water softener is essential for optimal performance. Regularly check the salt levels in the brine tank and refill when necessary. Monitor the system for any signs of leaks or malfunctions, such as reduced water pressure or unusual noises. Periodic cleaning of the resin bed may also be required to remove any buildup that could affect performance. Always consult your product manual for specific maintenance instructions and recommended cleaning products.
How often should I test my water hardness?
It is advisable to test your water hardness at least once a year, or more frequently if you notice changes in your water quality, such as increased scale buildup or changes in taste.
What type of salt should I use in my water softener?
Use high-purity salt specifically designed for water softeners. Avoid using table salt or other types of salt that may contain additives which can damage your system.
Can I use a water softener with well water?
Yes, water softeners can be used with well water, but it’s crucial to test the water for hardness and other contaminants. High levels of iron or other minerals may require a specific type of softener or additional filtration systems.
Salt or salt-free — your choice
Both approaches stop scale. They do it differently, and neither is automatically the right answer — pick the one that fits your water and your household.
Salt-based softener
Fleck 5600SXT 48,000 Grain Water Softener – Complete Whole-House System
Removes the calcium and magnesium from your water by ion exchange, so you get genuinely soft water: no scale, less soap, softer laundry and skin.
Needs salt topped up and a drain connection.
Buy now Full detailsSalt-free scale control
Salt-Free Eco Whole-Home System — No Salt, No Drain, No Waste
Leaves the minerals in the water but changes them so they stop sticking to pipes, heaters and fixtures — scale protection without softening.
No salt, no drain, no wastewater — and no soft-water feel.
Buy now Full details- ✓ 90-Day Money-BackNo restocking fees — return within 90 days.
- ✓ Manufacturer WarrantyGenuine Fleck · Pentair · VIQUA equipment.
- ✓ Free Expert SizingTalk to a specialist and buy the right system the first time.