Water Softener Calculators
Hardness (ppm) to GPG Calculator
Most water test kits and city water reports will display hardness as measured in parts per millions (ppm). While most water softeners will display settings and ratings in grains per gallon (GPG). This calculator will help you convert your water hardness to GPG for use with water softeners.
Grain Capacity Calculator
When you are picking out a water softener for your home, you will need to know a minimum grain capacity. This is based on your water hardness in GPG and the daily water usage of your home. By doing this calculation you can make sure your water softener can handle the amount of filtration needed for your specific situation.
Finding Water Hardness in ppm
If you need to test for water hardness, we recommend purchasing the Safe Home Basic 120 Test Kit. It includes DIY 10 test strips to help you find the appropriate softener, adjust settings, and monitor performance.
Setting your water softener
Each water softener and manufacturer uses slightly different programming, but the correct settings always start with one thing: your actual water hardness.
Use the calculators above to determine your hardness in grains per gallon (GPG), then reference your manufacturer’s manual to match that number to the proper setting on your unit.
Your goal is balanced softening, not the lowest possible hardness.
Water that is too soft can become more corrosive and more likely to leach metals from plumbing. It can also have that overly “silky” or slippery feel that many people notice when a softener is set too aggressively. Properly calculating your hardness and setting your softener accordingly gives you scale protection without creating new water quality issues.
To keep your system performing correctly, test your water hardness monthly with a DIY test strip. Softener performance drops when salt levels run low or when the unit isn’t regenerating properly, and you’ll often see hardness creep back up before you notice any other signs. Regular testing helps you catch that early and keep your water consistently balanced.