1 meq/L = 2.8 dKH = 50 ppm as CaCO₃. To go from dKH to meq/L, divide by 2.8. To go from dKH to ppm, multiply by 17.86. Type your reading below to convert it both ways at once.
Log 8.00 dKH in my Companion →Opens your free Reef Companion with the result filled in. No account needed.
The conversion factors
All three units describe the same thing: how much acid the water can neutralise. They just use different scales. The factors are fixed, so a conversion is exact.
| From | To | Do this |
|---|---|---|
| dKH | meq/L | ÷ 2.8 |
| dKH | ppm as CaCO₃ | × 17.86 |
| meq/L | dKH | × 2.8 |
| meq/L | ppm as CaCO₃ | × 50 |
| ppm as CaCO₃ | dKH | × 0.056 |
| ppm as CaCO₃ | meq/L | ÷ 50 |
Hanna Instruments gives the same dKH and ppm factors.
Common readings
Reef targets are usually quoted as 7–11 dKH, which is 2.5–4 meq/L or 125–200 ppm. Randy Holmes-Farley gives the range in all three units.
| dKH | meq/L | ppm as CaCO₃ |
|---|---|---|
| 7 | 2.50 | 125 |
| 7.5 | 2.68 | 134 |
| 8 | 2.86 | 143 |
| 8.5 | 3.04 | 152 |
| 9 | 3.21 | 161 |
| 10 | 3.57 | 179 |
| 11 | 3.93 | 196 |
Which unit should I use?
Most UK reef keepers and test kits use dKH, and so does the Reef Companion’s test log. Some kits and ICP reports use meq/L, and older kits sometimes give ppm. Pick one unit, convert everything into it, and stick to it so your log compares like with like.
Watch for “ppm” on its own. For alkalinity it means ppm as calcium carbonate, which isn’t the same as ppm of anything else. Don’t compare an alkalinity ppm figure with calcium in mg/L.
Next steps
Not sure what your number should be? Read what alkalinity should be in a reef tank. If you need to raise it, the alkalinity dosing calculator works out how much to add and over how many days.
Common questions
How many dKH is 1 meq/L?
2.8 dKH.
How do I convert ppm to dKH?
Multiply by 0.056, or divide by 17.86. For example, 143 ppm is about 8 dKH.
Is KH the same as alkalinity?
In reef keeping, yes. KH test kits measure total alkalinity, reported in dKH.
Sources and limits
Last checked 12 October 2026. The converter uses the standard factors shown. It converts units; it can’t make an inaccurate test reading more accurate.
- Hanna Instruments: how to test for alkalinity
- Randy Holmes-Farley, Reefkeeping: Reef Aquarium Water Parameters
Keep going
Alkalinity converter · Free Reef Companion · All calculators