IPA 99% vs 70%: which isopropyl alcohol should you buy?
The difference between 99% and 70% isopropyl alcohol, when to use each, and how to dilute safely.
Isopropyl alcohol (IPA, isopropanol) is sold mainly as 99% and 70%. They are not interchangeable.
IPA 99%
- Best for electronics and PCB cleaning - evaporates fast, leaves minimal residue.
- Used as a solvent in formulation, extraction, and cleaning where water is undesirable.
- Can be diluted down to 70% for disinfection.
IPA 70%
- Better as a surface disinfectant - the water content slows evaporation so it stays in contact longer and penetrates cell walls more effectively.
- Common in labs and healthcare surface cleaning.
Diluting 99% to 70%
To make 70% from 99%, mix roughly 7 parts IPA 99% with 2 parts distilled water (by volume) - this gives about 70%. Always add to a clean container, label it, and consult the SDS.
Safety
IPA is flammable. Keep away from ignition sources, use in ventilation, and store tightly closed. See the product SDS and our chemical safety guide.
Buy IPA and other alcohol solvents at Lubechem, in small packs to bulk drums.
Frequently asked questions
Which IPA is better for disinfecting - 99% or 70%?
70% is generally more effective as a disinfectant because the water content slows evaporation and helps it penetrate cell walls. 99% is better for electronics cleaning and as a solvent.
How do I dilute 99% IPA to 70%?
Mix roughly 7 parts IPA 99% with 2 parts distilled water by volume. Label the container and follow the SDS.