Water Hardness GPG To dH (dGH) Conversion + Chart

We have many different units for water hardness. If you have water hardness expressed in GPG (Grains Per Gallon), and you like to express it in terms of dH (degrees of Hardness; same as dGH or degrees of General Hardness), you have to convert GPG to dH.

To make this conversion easier for everybody, we at Waternity Lab created an easy-to use calculator that converts GPG to dH (same as GPG to dGH conversion) immediately.

Below the calculator, we also use 15 GPG to dH example to demonstrate how to use this calculator (we also do math-based 5 GPG to dH example).

On top of that, we explain the math behind the conversion, as well as feature a conversion chart where we have converted 0.1 – 50 GPG to dH, and summarized the result in a color-coded chart (color = water hardness categorization, more about this later on).

Here is the online GPG to dH calculator you can freely use:

 

Now, let’s look at that example: How many dH is 15 GPG?

You just slide the GPG slider to ‘15.0’, and you get the result immediately in this form:

converting 8 gpg to dh or dgh

You can see right away that 15 GPG is equal to 14.39 dH (or dGH, since this is the same unit).

Additionally, you can also see that water with a 15 GPG or 14.39 dH hardness is categorized as “Very Hard” water.

Let’s look at the math behind this conversion:

How To Convert GPG To dH (dGH)?

Namely, we only need to know this 1 conversion relationship:

1 dH = 0.9591 GPG

This means that 1 dH is equal to 0.9591 GPG. Thus, we can write the GPG to dH conversion formula like this:

dH = GPG × 0.9591

To calculate how many dH any number of grains per gallon (GPG) is, we have to multiply GPG by 0.9591.

Let’s solve this example with a bit of math: How many dH is 5 GPG? We just insert 5 GPG into the equation and calculate the resulting dH like this:

dH (5 GPG) = 5 GPG × 0.9591 = 4.80 dH

We can see that 5 GPG is equal to 4.80 dH (or dGH, also known as “German” degrees). You can use the calculator above to confirm this; just slide the GPG slider to ‘5.0’.

Here is the conversion chart. This chart is color-coded, based on the water hardness categorization: soft water (0 – 3.5 GPG) is denoted with this green color, moderately hard water (3.56 – 7.01 GPG) with this light blue color, hard water (7.06 – 10.51 GPG) with this blue color, and very hard water (10.57+ GPG) with this dark blue color as per water hardness scale seen here:

GPG To dH (dGH) Conversion Chart

GPG (Grains Per Gallon): dH or dGH (degrees of General Hardness):
0.1 GPG 0.10 dH
0.2 GPG 0.19 dH
0.3 GPG 0.29 dH
0.4 GPG 0.38 dH
0.5 GPG 0.48 dH
0.6 GPG 0.58 dH
0.7 GPG 0.67 dH
0.8 GPG 0.77 dH
0.9 GPG 0.86 dH
1 GPG 0.96 dH
1.5 GPG 1.44 dH
2 GPG 1.92 dH
2.5 GPG 2.40 dH
3 GPG 2.88 dH
3.5 GPG 3.36 dH
4 GPG 3.84 dH
4.5 GPG 4.32 dH
5 GPG 4.80 dH
5.5 GPG 5.28 dH
6 GPG 5.75 dH
6.5 GPG 6.23 dH
7 GPG 6.71 dH
7.5 GPG 7.19 dH
8 GPG 7.67 dH
8.5 GPG 8.15 dH
9 GPG 8.63 dH
9.5 GPG 9.11 dH
10 GPG 9.59 dH
11 GPG 10.55 dH
12 GPG 11.51 dH
13 GPG 12.47 dH
14 GPG 13.43 dH
15 GPG 14.39 dH
16 GPG 15.35 dH
17 GPG 16.30 dH
18 GPG 17.26 dH
19 GPG 18.22 dH
20 GPG 19.18 dH
21 GPG 20.14 dH
22 GPG 21.10 dH
23 GPG 22.06 dH
24 GPG 23.02 dH
25 GPG 23.98 dH
26 GPG 24.94 dH
27 GPG 25.90 dH
28 GPG 26.85 dH
29 GPG 27.81 dH
30 GPG 28.77 dH
35 GPG 33.57 dH
40 GPG 38.36 dH
45 GPG 43.16 dH
50 GPG 47.96 dH

Based on this conversion chart, we can quickly see that (in accordance with the water hardness scale here):

  • “Soft” water has 0 – 3.5 GPG or 0 – 3.36 dH water hardness.
  • “Moderately Hard” water has 3.6 – 7 GPG or 3.37 – 6.71 dH water hardness.
  • “Hard” water has 7.5 – 10 GPG or 6.72 – 9.59 dH water hardness.
  • “Very Hard” water has more than 10 GPG or more than 9.59 dH water hardness.

Hopefully, now you understand everything about the water hardness GPG to dH conversion. You can use the calculator, this chart, or even do the math yourself. If you need any help from us, you can use the comment section below, give us a few numbers, and we can do a bit of math for you.

Here are some similar calculators that might be helpful:

Thank you.

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