dKH → PPM

Enter value in dKH

dKH

Typical Ranges

↓

— ppm

—

Formula: ppm = dKH × 17.848
Expressed as CaCO₃ equivalent (mg/L)

PPM → dKH

Enter value in PPM (mg/L as CaCO₃)

ppm

Common Values

↓

— dKH

—

Formula: dKH = ppm ÷ 17.848
Assumes ppm measured as CaCO₃ equivalent

dKH to PPM Conversion Table — Alkalinity Reference Chart

dKH (Degrees Carbonate Hardness)	PPM (mg/L as CaCO₃)	mEq/L	Water Type
1 dKH	17.85 ppm	0.357 mEq/L	Very Soft
2 dKH	35.7 ppm	0.714 mEq/L	Very Soft
3 dKH	53.54 ppm	1.071 mEq/L	Soft
4 dKH	71.39 ppm	1.428 mEq/L	Soft
5 dKH	89.24 ppm	1.785 mEq/L	Moderately Soft
6 dKH	107.09 ppm	2.142 mEq/L	Moderately Soft
7 dKH	124.94 ppm	2.499 mEq/L	Ideal (Freshwater)
8 dKH	142.78 ppm	2.856 mEq/L	Ideal (Freshwater)
9 dKH	160.63 ppm	3.213 mEq/L	Moderately Hard
10 dKH	178.48 ppm	3.57 mEq/L	Moderately Hard
12 dKH	214.18 ppm	4.284 mEq/L	Hard
15 dKH	267.72 ppm	5.355 mEq/L	Hard
18 dKH	321.26 ppm	6.426 mEq/L	Very Hard
20 dKH	356.96 ppm	7.14 mEq/L	Very Hard
25 dKH	446.2 ppm	8.925 mEq/L	Extremely Hard

Ideal Alkalinity Ranges by Use

🐠

Freshwater Aquarium

4 – 8 dKH

71 – 143 ppm

🪸

Reef / Saltwater Tank

8 – 12 dKH

143 – 214 ppm

🚰

Drinking Water (WHO)

2 – 9 dKH

36 – 161 ppm

🌊

Swimming Pool

7 – 11 dKH

125 – 196 ppm

ⓘ 1 dKH = 17.848 ppm (mg/L as CaCO₃) = 0.357 mEq/L. dKH (degrees of carbonate hardness, also written °KH or KH) measures the concentration of bicarbonate and carbonate ions in water. It is the primary measure of a water body's buffering capacity — its ability to resist pH changes.

dKH to PPM Converter

dKH to PPM Conversion Table — Alkalinity Reference Chart

Ideal Alkalinity Ranges by Use