Water Hardness dH To PPM Conversion Calculator (+ Chart)

In order to determine if you have hard water, you will often have to convert dH to PPM. This is the conversion from degrees of general hardness (or German degrees) used internationally to parts per million hard water unit, primarily used in the US.

To help everybody out with this conversion, we have created these three easy-to-use resources:

  1. dH To PPM Calculator. You just insert water hardness in dH, and the calculator will automatically convert that to PPM.
  2. dh To PPM Chart. This is a conversion chart where we have converted dH from 0 to 50 dH into PPM. In the chart, we have denoted soft water (0 to 3.37 dH) with this green color, moderately hard water (3.38 to 6.74 dH) with this light blue color, hard water (6.75 to 10.11 dH) with this blue color, and very hard water (over 10.12 dH) with this dark blue color.
  3. Water hardness dH chart. Lastly, we will look at how many dH is hard water; you can just look at this chart, use the calculator and/or chart, and check how hard your water is.
    hard water dh degrees to ppm
    Water hardness scale in terms of PPM. Below 60 PPM or 3.37 dH, we have soft water.

Let’s first look at the water hardness units we are using in this conversion:

  • dH or degree of Hardness (also referred to as the degree of General Hardness (dGH) or German degree) is a unit of water hardness equal to 10 mg/L of calcium oxide (CaO).
  • PPM or Part Per Million is a unit of water hardness equal to 1 mg/L of calcium carbonate (CaCO3).

As we can see both of these hard water units are determined in terms of milligrams per liter, but the dH refers to CaO while PPM refers to CaCO3. For conversion, we need to use this dH to PPM formula:

PPM = dH × 17.848

That means that 1 dH is equal to 17.848 PPM.

Example: Let’s say that our water has 5 dH of water hardness; how much is 5 dH in PPM? We just insert 5 dH in the equation like this:

PPM (5 dH) = 5 × 17.848 = 89.24 PPM

This is just one example. To help you with the calculation for all other dH values, you can use the calculator, complete with the conversion chart further on. As we will see in the water hardness dH chart (at the end), 5 dH is considered moderately hard water.

dH To PPM Calculator


Here is an example of how to use this conversion calculator: Let’s say we want to convert 3 dH to PPM. Just slide the slider to ‘3’ and we get the result: 3 dH is equal to 53.54 PPM.

Here is the complete 0 to 50 dH conversion chart (resulting in 0 to 892.4 PPM):

dH To PPM Conversion Chart

dH (degrees of Hardness or German Degrees): PPM (Parts Per Million):
0 dH 0 PPM
0.1 dH 1.78 PPM
0.5 dH 8.92 PPM
1.0 dH 17.85 PPM
1.5 dH 26.77 PPM
2.0 dH 35.70 PPM
2.5 dH 44.62 PPM
3.0 dH 53.54 PPM
3.5 dH 62.47 PPM
4.0 dH 71.39 PPM
4.5 dH 80.32 PPM
5.0 dH 89.24 PPM
5.5 dH 98.16 PPM
6.0 dH 107.09 PPM
6.5 dH 116.01 PPM
7.0 dH 124.94 PPM
7.5 dH 133.86 PPM
8.0 dH 142.78 PPM
8.5 dH 151.71 PPM
9.0 dH 160.63 PPM
9.5 dH 169.56 PPM
10 dH 178.48 PPM
11 dH 196.33 PPM
12 dH 214.18 PPM
13 dH 232.02 PPM
14 dH 249.87 PPM
15 dH 267.72 PPM
16 dH 285.57 PPM
17 dH 303.42 PPM
18 dH 321.26 PPM
19 dH 339.11 PPM
20 dH 356.96 PPM
21 dH 374.81 PPM
22 dH 392.66 PPM
23 dH 410.50 PPM
24 dH 428.35 PPM
25 dH 446.20 PPM
26 dH 464.05 PPM
27 dH 481.90 PPM
28 dH 499.74 PPM
29 dH 517.59 PPM
30 dH 535.44 PPM
35 dH 624.68 PPM
40 dH 713.92 PPM
45 dH 803.16 PPM
50 dH 892.40 PPM

If you know how hard your water is in terms of dH (degrees of Hardness) and want to know how hard the water is in PPM, you can just read it of this chart.

Example: How hard is a 10 dH water in terms of PPM? Checking the chart, we see that 10 dH is equal to 178.48 PPM. The blue color will also tell us that this water can be categorized as ‘hard’.

Water Hardness dH Chart

To fully underhand if you have soft or hard water based on the dH (or PPM), you can consult this chart:

Classification degrees of Hardness (dH) Hardness (PPM)
Soft 0 – 3.37 0 – 60
Moderately hard 3.38 – 6.74 61 – 120
Hard 6.75 – 10.11  121 – 180
Very hard 10.12 Or More  181 Or More

Now you know that, for example, 2 dH water is considered soft water and 14 dH water is considered very hard water.

We hope this makes clear how to convert dH to PPM (hard water units). If you haven’t found the answer, you can give us some numbers in the comment section below, and we will help you out.

2 thoughts on “Water Hardness dH To PPM Conversion Calculator (+ Chart)”

    • Hi Melvin, that water company report seems to be 181 PPM which corresponds to ‘very hard water’, just over the 180 PPM limit. The Culligan report is in PPM as well? That wouldn’t make much sense; the difference is 10x here.


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