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KOH Solution Freezing Point Calculator
(and Phase Diagrams)
The specific freezing point of a KOH solution is very useful; however we recommend you always consider the phase diagram to help understand the sensitivity of the KOH solution to temperature. More detailed drawings of the KOH-Water phase diagram are Diagram (Freezing/Melting Point Curve) 0-80% KOH and Phase Diagram (Freezing/Melting Point Curve) 80-100% KOH.

This calculator determines the approximate freezing point for a "pure" KOH-water solution and should be adequate for the vast majority of situations. The actual freezing point of your KOH solution may be somewhat different depending on the amounts of various constituents that can be present in KOH. If you have a situation where it is critical to know the exact freezing point of a KOH solution, you should test the particular solution to determine its specific freezing point.

Phase Diagram - Composition of Solids
Compounds Maximums   Transition Points
Concentration Temperature Concentration Temperature
(wt%) (°C) (°F) (wt%) (°C) (°F)
A Ice 0.0 0.0 32.0 A to B 30.8 * -65.2 -85.4
B KOH•4H2O 43.8 -32.9 -27.2 B to C 44.8 -33.0 -27.4
C KOH•2H2O 60.9 75.3 167.5 C to D 57.4 33.0 91.4
D KOH•H2O 75.7 147.2 297.0 D to E 87.0 * 99.0 210.2
E KOH 100.0 406.0 762.8        
              * - Eutectic Point 

What concentration of KOH do you have? (0-100 wt%)



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