°dH to PPM — water hardness converter
The German degree (°dH) measures hardness in much of Europe; one °dH equals 17.848 mg/L, and mg/L equals ppm for hardness — so to convert °dH to ppm you multiply by 17.848. For example, 10 °dH × 17.848 = 178 ppm, which is hard water. US reports use ppm; German charts use °dH.
European charts use the German degree (°dH); US reports use ppm — this bridges the two.
Convert °dH to ppm
Enter a number to convert; the result shows its band and how it ranks among 2,977 US counties.
Chart
°dH to ppm chart
| °dH | ppm | Band |
|---|---|---|
| 1 | 18 | Soft |
| 2 | 36 | Soft |
| 3 | 54 | Soft |
| 5 | 89 | Moderately hard |
| 7 | 125 | Hard |
| 10 | 178 | Hard |
| 12 | 214 | Very hard |
| 15 | 268 | Very hard |
| 20 | 357 | Very hard |
| 25 | 446 | Very hard |
| 30 | 535 | Very hard |
Formula
The formula, and why
ppm = °dH × 17.848. One German degree (°dH) is defined as 10 mg/L of calcium oxide (CaO); converting to calcium carbonate by molar mass, 10 × (100.087 ÷ 56.077) = 17.848 mg/L per °dH.
Reverse: PPM to °dH · ppm→gpg · gpg→ppm · gpg→°dH · all-units calculator
Questions
Frequently asked
- How many ppm is 1 °dH?
- 17.848 ppm — one German degree equals 17.848 mg/L, and mg/L equals ppm.
- Is dGH the same as °dH?
- Yes — dGH (German general hardness) is the same unit as °dH.
- What is 7 °dH in ppm?
- 7 × 17.848 = 125 ppm, which is hard.
By Marko Visic, MPharm, BSc Physics. Source: Conversion factors per USGS/NIST unit definitions; band data from USGS/EPA WQP. Data last verified . Methodology.