According to the Water Quality Association, water hardness classifications are defined as follows: soft water has 0-3.5 grains per gallon (gpg), moderate hardness ranges from 3.5-7.0 gpg, hard water is characterized by 7.0-10.5 gpg, and very hard water is identified as having over 10.5 gpg.
This blog introduces user-friendly tools for this purpose:
| Grains Per Gallon (GPG): | Parts Per Million (PPM): | Rating |
|---|---|---|
| 0.06 gpg | 1 ppm | Soft |
| 0.29 gpg | 5 ppm | Soft |
| 0.58 gpg | 10 ppm | Soft |
| 0.88 gpg | 15 ppm | Soft |
| 1.17 gpg | 20 ppm | Soft |
| 1.46 gpg | 25 ppm | Soft |
| 1.75 gpg | 30 ppm | Soft |
| 2.04 gpg | 35 ppm | Soft |
| 2.34 gpg | 40 ppm | Soft |
| 2.63 gpg | 45 ppm | Soft |
| 2.92 gpg | 50 ppm | Soft |
| 3.21 gpg | 55 ppm | Soft |
| 3.51 gpg | 60 ppm | Soft |
| 3.80 gpg | 65 ppm | Moderately Hard Water |
| 4.38 gpg | 75 ppm | Moderately Hard Water |
| 4.67 gpg | 80 ppm | Moderately Hard Water |
| 4.97 gpg | 85 ppm | Moderately Hard Water |
| 5.26 gpg | 90 ppm | Moderately Hard Water |
| 5.84 gpg | 100 ppm | Moderately Hard Water |
| 6.43 gpg | 110 ppm | Moderately Hard Water |
| 7.01 gpg | 120 ppm | Moderately Hard Water |
| 7.59 gpg | 130 ppm | Hard Water |
| 8.18 gpg | 140 ppm | Hard Water |
| 8.76 gpg | 150 ppm | Hard Water |
| 9.35 gpg | 160 ppm | Hard Water |
| 9.93 gpg | 170 ppm | Hard Water |
| 10.52 gpg | 180 ppm | Hard Water |
| 11.10 gpg | 190 ppm | Very Hard Water |
| 11.68 gpg | 200 ppm | Very Hard Water |
| 14.60 gpg | 250 ppm | Very Hard Water |
| 17.53 gpg | 300 ppm | Very Hard Water |
| 20.45 gpg | 350 ppm | Very Hard Water |
| 23.37 gpg | 400 ppm | Very Hard Water |
| 26.29 gpg | 450 ppm | Very Hard Water |
| 29.21 gpg | 500 ppm | Very Hard Water |
Gain a deeper understanding of water hardness by learning to convert GPG to PPM manually.
The formula is simple: PPM = GPG * 17.1.
For instance, converting 5 GPG to PPM: PPM = 5 * 17.1 = 85.5 PPM
This method ensures you can independently verify your water’s hardness level.
With water hardness affecting many U.S. homes, identifying your area’s level is key. Water hardness charts by state or city and local water authorities provide essential data. Visit this Amazing go-to resource on Water Hardness by state and zip-code
| Grains Per Gallon (GPG) | Parts Per Million (PPM) | Water Hardness Rating |
|---|---|---|
| 0.00 - 3.51 GPG | 0-60 PPM | Soft Water |
| 3.57 - 7.02 GPG | 61-120 PPM | Moderately Hard Water |
| 7.08 - 10.53 GPG | 121-180 PPM | Hard Water |
| 10.58+ GPG | 181+ PPM | Very Hard Water |
To convert grains per gallon (GPG) to parts per million (PPM), multiply the GPG value by 17.1. For instance, 5 GPG equals 85.5 PPM.
Grains hardness to PPM refers to converting the hardness measurement from grains per gallon, a traditional unit, to parts per million, a more widely used unit.
Similar to converting GPG, multiply the grains of hardness value by 17.1 to convert it to PPM.
Water hardness measured in grains (per gallon) can be converted to PPM by multiplying the grain value by 17.1, providing a standardized measurement.
The conversion process involves multiplying the number of grains (per gallon) by 17.1 to get the equivalent parts per million (PPM).
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