Brine Freezing Point Chart
The freezing point of salt (sodium chloride) and calcium chloride brine at each strength by weight, in °F or °C.
How to use ↓Wt % = grams of salt per 100 g of brine. Freeze points are rounded toward the warmer side. Typical values for reference only. Inhibited glycols and brines vary by maker: always use the manufacturer’s data for the fluid you are using.
Sodium chloride (NaCl)
| Wt % | Freezes at °F°C |
|---|---|
| 1 | 31.0−0.5 |
| 2 | 29.9−1.1 |
| 3 | 28.8−1.7 |
| 4 | 27.7−2.4 |
| 5 | 26.6−3.0 |
| 6 | 25.4−3.7 |
| 7 | 24.2−4.3 |
| 8 | 22.9−5.0 |
| 9 | 21.6−5.8 |
| 10 | 20.2−6.5 |
| 12 | 17.3−8.1 |
| 14 | 14.2−9.9 |
| 16 | 10.6−11.8 |
| 18 | 6.8−14.0 |
| 20 | 2.4−16.4 |
| 22 | −2.5−19.1 |
Calcium chloride (CaCl₂)
| Wt % | Freezes at °F°C |
|---|---|
| 1 | 31.3−0.4 |
| 2 | 30.5−0.8 |
| 3 | 29.7−1.3 |
| 4 | 28.8−1.8 |
| 5 | 27.8−2.3 |
| 6 | 26.8−2.9 |
| 7 | 25.6−3.5 |
| 8 | 24.3−4.2 |
| 9 | 23.0−5.0 |
| 10 | 21.5−5.8 |
| 12 | 18.2−7.7 |
| 14 | 14.4−9.8 |
| 16 | 9.9−12.2 |
| 18 | 4.9−15.1 |
| 20 | −0.9−18.3 |
| 22 | −7.0−21.7 |
| 24 | −13.5−25.3 |
| 26 | −21.4−29.7 |
| 28 | −30.4−34.7 |
| 30 | −41.8−41.0 |
Sodium chloride brine bottoms out at about 23% (about −5.9−21.1 °F°C); adding more salt does not lower it further. Above about 22%, calcium chloride figures from different sources spread widely, so the warmest published value is shown.
How to use
- Pick the salt: sodium chloride or calcium chloride.
- Find the freeze point you need, with a margin below the lowest brine temperature.
- Read the weight % on the left. Check strength with a hydrometer or refractometer.
About brine freeze points
Brine is still used in ice rinks, older industrial plants and some process chillers. 20% sodium chloride freezes at about 2.4 °F (−16.4 °C) and 20% calcium chloride at about −0.9 °F (−18.3 °C). Both are corrosive, so the loop needs inhibitors and regular testing.
Source: CRC Handbook of Chemistry and Physics, Concentrative Properties of Aqueous Solutions (freezing point depression), cross-checked against independent brine property data. The sodium chloride values also agree with the Morton Salt brine freezing point table. Typical values for reference only. Inhibited glycols and brines vary by maker: always use the manufacturer’s data for the fluid you are using.
FAQ
What is the freezing point of salt water?
It depends on the strength: about 20.2 °F at 10% sodium chloride and about 2.4 °F at 20%. Sea water (about 3.5% salt) freezes at about 28 °F (−1.9 °C).
What is the lowest freezing point of salt brine?
About −6 °F (−21 °C), at roughly 23% salt by weight. Stronger brine than that freezes at a warmer temperature, not a colder one.
Which brine goes colder?
Calcium chloride. Sodium chloride stops at about −21 °C (−6 °F); calcium chloride goes far lower.