Treatment chemicals by strength
Pick the chemical, enter the strength on the label, and read its specific gravity, density, weight per gallon and how much of the active chemical each gallon carries.
Percent H2SO4 by weight. Sourced from 93.19 to 98 % at 15.6 °C.
| Specific gravity (15.6 °C) | 1.835 |
| Density | 1.834 g/mL (1,834 kg/m³) |
| Weight per US gallon | 15.3 lb/gal |
| H2SO4 per US gallon | 14.3 lb/gal |
| H2SO4 per litre | 1.71 kg/L |
Specific gravity at 60/60 °F from a sulphuric acid grade chart. Only the commercial grades, 93.19 to 98 %, are sourced.
| Chemical | Strength | SG | lb/gal | Active lb/gal |
|---|---|---|---|---|
| Sulfuric acid | 93.19 % | 1.835 | 15.3 | 14.3 |
| Sulfuric acid | 98 % | 1.844 | 15.37 | 15.1 |
| Hydrochloric acid | 31.45 % | 1.159 | 9.663 | 3.04 |
| Hydrochloric acid | 35.21 % | 1.178 | 9.821 | 3.46 |
| Phosphoric acid | 75 % | 1.58 | 13.15 | 9.86 |
| Phosphoric acid | 80 % | 1.633 | 13.59 | 10.9 |
| Phosphoric acid | 85 % | 1.69 | 14.07 | 12 |
| Sodium hydroxide | 25 % | 1.276 | 10.63 | 2.66 |
| Sodium hydroxide | 50 % | 1.528 | 12.73 | 6.36 |
| Potassium hydroxide | 45 % | 1.456 | 12.13 | 5.46 |
| Potassium hydroxide | 50 % | 1.515 | 12.62 | 6.31 |
| Sodium hypochlorite | 10 % | 1.132 | 9.43 | 0.835 |
| Sodium hypochlorite | 12.5 % | 1.163 | 9.687 | 1.04 |
| Ferric chloride | 40 % | 1.418 | 11.81 | 4.72 |
| Aluminium sulphate (liquid alum) | 48.5 % | 1.335 | 11.13 | 5.4 |
Why the specific gravity matters
A chemical feed pump moves volume, but a dose is a mass. Specific gravity is the bridge: a gallon of 93 % sulfuric acid weighs far more than a gallon of water and carries most of that weight as acid, so reading the pump in gallons and the dose in pounds without it is the classic overfeed.
Density rises with strength, so the strength on the label and the specific gravity should agree. A hydrometer reading that does not match the label is worth a second look: a product can be diluted, mislabelled, or, for hypochlorite, partly decayed.
The values are for the temperature stated with each chemical. Most solutions get a little less dense as they warm, by a few tenths of a percent over the range a chemical room sees, which matters for custody transfer and rarely for a dose.
- Sulphuric acid grade and specific gravity chart (CCC Group)
- OxyChem, Hydrochloric Acid Handbook, Table 3
- Phosphoric acid technical bulletin, specific gravity table (ASTM E 358)
- Covestro, caustic soda 50 % product data, density at 20 °C
- Potassium hydroxide density at 20 °C, after Akerlof and Bender (1941)
- Chlorine Institute, Pamphlet 96, Sodium Hypochlorite Manual, Table 2-2
- Solvay, Ferric Chloride: Density (2006)
- Washington State Department of Health, Publication 331-650, liquid alum
Cite this page
formula.expert. (2026, October 16). Treatment chemicals: specific gravity by strength. https://formula.expert/fluids/treatment-chemicals