In the US, we primarily use PPM units for water hardness. dH or degrees of Hardness (also known as dGH or German degrees) is used internationally. In some cases, you will need to convert PPM to dH.
To help you out, we have all you need to make this conversion, namely:
- PPM To dH Calculator. Basically, just insert PPM, and you get dH.
- PPM to dH Conversion Chart. We have converted PPM from 0 to 1000 PPM into dH. The chart is also color-coded: Soft water (0-60 ppm) is marked with this green color, moderately hard water (61-120 ppm) is marked with light blue color, hard water (121-180 ppm) is marked with this blue color, and very hard water (181+ ppm) is marked with this dark blue color.
- Water Hardness PPM To dH Chart. This is a chart that will tell you how many dH (and PPM) does soft, moderately hard, hard, and very hard water have.
Here are the hard water units we are converting:
- PPM or Part Per Million is a unit of water hardness equal to 1 mg/L of calcium carbonate (CaCO3).
- 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).
Obviously, we are looking at mg/L in both cases, but at different dissolved solids (CaCO3 for PPM, CaO for dH).
That’s why we need to use this PPM to dH conversion formula:
dH = PPM / 17.848
Basically, to convert PPM to dH, we have to divide PPM by a 17.848 factor.
Example: How many dH is 1 PPM water hardness? We just insert this into the equation and calculate the result like this:
dH (1 PPM) = 1 / 17.848 = 0.056 dH
As we can see, 1 dH is equal to 0.056 dH.
This is just an example for 1 dH. For all other conversions, you can use the following calculator (and consult the chart below the calculator). At the end, you will also be able to compare the calculated dH with a water hardness scale to determine how hard water you have:
Table of Contents
PPM To dH Calculator
Let’s say we want to convert 60 PPM to dH using this calculator. You slide the slider to ’60’ and get the result immediately: 60 PPM is equal to 3.36 dH.
Here is the full conversion chart where we converted 0 to 1000 PPM into dH:
PPM To dH Chart
| PPM (Parts Per Million): | dH (degrees of Hardness or German Degrees): |
| 0 PPM | 0.056 dH |
| 1 PPM | 1.78 PPM |
| 5 PPM | 0.28 dH |
| 10 PPM | 0.56 dH |
| 15 PPM | 0.84 dH |
| 20 PPM | 1.12 dH |
| 25 PPM | 1.40 dH |
| 30 PPM | 1.68 dH |
| 35 PPM | 1.96 dH |
| 40 PPM | 2.24 dH |
| 45 PPM | 2.52 dH |
| 50 PPM | 2.80 dH |
| 60 PPM | 3.36 dH |
| 70 PPM | 3.92 dH |
| 80 PPM | 4.48 dH |
| 90 PPM | 5.04 dH |
| 100 PPM | 5.60 dH |
| 110 PPM | 6.16 dH |
| 120 PPM | 6.72 dH |
| 130 PPM | 7.28 dH |
| 140 PPM | 7.84 dH |
| 150 PPM | 8.40 dH |
| 160 PPM | 8.96 dH |
| 170 PPM | 9.52 dH |
| 180 PPM | 10.09 dH |
| 190 PPM | 10.65 dH |
| 200 PPM | 11.21 dH |
| 250 PPM | 14.01 dH |
| 300 PPM | 16.81 dH |
| 350 PPM | 19.61 dH |
| 400 PPM | 22.41 dH |
| 450 PPM | 25.21 dH |
| 500 PPM | 28.01 dH |
| 550 PPM | 30.82 dH |
| 600 PPM | 33.62 dH |
| 650 PPM | 36.42 dH |
| 700 PPM | 39.22 dH |
| 750 PPM | 42.02 dH |
| 800 PPM | 44.82 dH |
| 850 PPM | 47.62 dH |
| 900 PPM | 50.43 dH |
| 950 PPM | 53.23 dH |
| 1000 PPM | 56.03 dH |
If you need to convert PPM to dH, you can just look at this chart.
Example: How many dH is 100 PPM? Simple. Just look at this chart and you have the result: 100 PPM is equal to 5.60 dH. This is considered moderately hard water (hence the light blue color in the chart).
Let’s look at the water hardness chart for PPM and dH to get an idea how many PPM or dH is hard water:
Water Hardness PPM Chart
| Classification | Hardness (PPM) | degrees of Hardness (dH) |
|---|---|---|
| Soft | 0 – 60 | 0 – 3.37 |
| Moderately hard | 61 – 120 | 3.38 – 6.74 |
| Hard | 121 – 180 | 6.75 – 10.11 |
| Very hard | 181 Or More | 10.12 Or More |
As you can see, you should have below 60 PPM or below 3.38 dH for soft water. Very hard water starts at 181 PPM or more or at 10.12 dH or more.
Hopefully, using the PPM to dH calculator, chart, and consulting this hard water chart, will help you determine how hard your water is and by how much PPM or dH you should decrease the water hardness for your water to be considered soft and safe to use.
If you have any questions or would like for us to calculate water hardness for you, you can use the comment section below, give us some numbers, and we’ll help you out.
Thank you.
my calculation is as follows – 371ppm = 20.79dH (very Hard)
what to do for softer water?
we have a new ISpring water softner.
Hi Brian, 371 ppm is still very hard, yes. If you want to get soft water, you should bring that down below 60 ppm, and water softeners are the best way to do that. That iSpring water softener doesn’t seem to be doing the job, though. There might be a problem wit the softener itself, it may have lower-than-needed capacity, or you might have a very hard water to begin with.
The first things you should do is troubleshoot and test if the water softener is working fine. It might be that there is a problem there.