Water Hardness PPM To GPG Calculator (+ PPM To GPG Chart)

Water hardness in the US is measured either in ppm (parts per million) or gpg (grains per gallon).

Parts per million, also referred to as American degrees, is a water hardness unit equal to 1 mg/L CaCO3 dissolved in water.

Grains per gallon is also a water hardness unit defined as 1 grain of CaCO3 dissolved in water.

We have created two useful resources for ppm to gph conversion:

  1. ppm To gpg Water Hardness Calculator. Just insert ppm, and the calculator will dynamically determine the equivalent gpg water hardness.
  2. ppm To gpg Water Hardness Chart. We have converted 1 to 1000 ppm into gpg, and summarized the results in the chart below. We have denoted soft water (0-60 ppm) with this green color, moderately hard water (61-120 ppm) with this light blue color, hard water (121-180 ppm) with this blue color, and very hard water (181+ ppm) with this dark blue color.

In order to convert ppm to GPG, you can use this converter:

 

How To Convert PPM To GPG?

The common denominator between ppm and gpg is a reference to water hardness measured as a quantity of CaCO3 dissolved in water.

Here is a formula that enables you to calculate gpg from ppm:

gpg = ppm/17.118

In essence, if you divide parts per million by 17.118, you get grains per gallon. Factor 17.118 comes from the volumetric and mass difference between the water hardness units.

Thus every 1 gpg is equal to 17.118 ppm (1 gpg = 17.118 ppm).

Water hardness calculations are most relevant for water softener systems.

Water Hardness PPM To GPG Chart

Parts Per Million (PPM): Grains Per Gallon (GPG):
1 ppm 0.06 gpg
2 ppm 0.12 gpg
3 ppm 0.18 gpg
4 ppm 0.23 gpg
5 ppm 0.29 gpg
6 ppm 0.35 gpg
7 ppm 0.41 gpg
8 ppm 0.47 gpg
9 ppm 0.53 gpg
10 ppm 0.58 gpg
15 ppm 0.88 gpg
20 ppm 1.17 gpg
25 ppm 1.46 gpg
30 ppm 1.75 gpg
35 ppm 2.04 gpg
40 ppm 2.34 gpg
45 ppm 2.63 gpg
50 ppm 2.92 gpg
55 ppm 3.21 gpg
60 ppm 3.51 gpg
65 ppm 3.80 gpg
70 ppm 4.09 gpg
75 ppm 4.38 gpg
80 ppm 4.67 gpg
85 ppm 4.97 gpg
90 ppm 5.26 gpg
95 ppm 5.55 gpg
100 ppm 5.84 gpg
110 ppm 6.43 gpg
120 ppm 7.01 gpg
130 ppm 7.59 gpg
140 ppm 8.18 gpg
150 ppm 8.76 gpg
160 ppm 9.35 gpg
170 ppm 9.93 gpg
180 ppm 10.52 gpg
190 ppm 11.10 gpg
200 ppm 11.68 gpg
210 ppm 12.27 gpg
220 ppm 12.85 gpg
230 ppm 13.44 gpg
240 ppm 14.02 gpg
250 ppm 14.60 gpg
260 ppm 15.19 gpg
270 ppm 15.77 gpg
280 ppm 16.36 gpg
290 ppm 16.94 gpg
300 ppm 17.53 gpg
310 ppm 18.11 gpg
320 ppm 18.69 gpg
330 ppm 19.28 gpg
340 ppm 19.86 gpg
350 ppm 20.45 gpg
360 ppm 21.03 gpg
370 ppm 21.61 gpg
380 ppm 22.20 gpg
390 ppm 22.78 gpg
400 ppm 23.37 gpg
410 ppm 23.95 gpg
420 ppm 24.54 gpg
430 ppm 25.12 gpg
440 ppm 25.70 gpg
450 ppm 26.29 gpg
460 ppm 26.87 gpg
470 ppm 27.46 gpg
480 ppm 28.04 gpg
490 ppm 28.62 gpg
500 ppm 29.21 gpg
550 ppm 32.13 gpg
600 ppm 35.05 gpg
650 ppm 37.97 gpg
700 ppm 40.89 gpg
750 ppm 43.81 gpg
800 ppm 46.73 gpg
850 ppm 49.66 gpg
900 ppm 52.58 gpg
950 ppm 55.50 gpg
1000 ppm 58.42 gpg

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