Isopropyl Alcohol (also known as Rubbing Alcohol) is a very common disinfectant used by pharmaceutical companies, hospitals and clean rooms. It’s also used in the purification of electronics and medical device manufacture. Isopropyl Alcohol (henceforth called IPA) has different purity grades with each meant for a different use. On a whole, they’re beneficial for cleaning and disinfecting.
At Craftiviti, we sell 99.8% IPA which means that it only has 0.2% water and thus, evaporates quickly. It’s meant to be used in Melt & Pour Soap making so the alcohol will disperse bubbles and create a smooth surface, and Cold Process Soap making which helps prevent soda ash from forming when IPA sprayed within 10-15 minutes of pouring your fresh soap.
However, it should be noted that 99.8% takes a greater time to act and doesn’t kill as much bacteria as 70% IPA. Thus, for this post, we’ll be sharing how you can calculate the amount of distilled water needed to dilute your 99.8% IPA to 70% IPA.
To read more about the difference between high concentrations of IPA compared to lower concentrations, you can check out this post by Lab Pro Inc.
Formula
To make 100ml of 70% IPA from 99.8% IPA, you can use the following:
To make it simpler, all you need is:
70ml 99.8% IPA + 30ml Distilled Water = 100ml 70% IPA
You can use your phone’s calculator to calculate this for you, and you can also replace the 100ml with any desired volume.
Thanks for reading and we hope this helps ❤️
PS: We are not chemists or pharmacists. The above formula was obtained from the research of others (the most relevant of which are cited below) and we are simply sharing it here. Though, we have gotten it verified by people in the same fields and they have said that it is fine for sanitization purposes.
Other Covid-related posts here:
👉 Washing Hands with Soap Kills Coronavirus
👉 Are Natural Hand Sanitizers as Effective as Alcohol-Based Hand Sanitizers?
👉 Do Essential Oils Help Kill Viruses?
References:
- Choudhary, Ankur, “Why 70% Isopropyl Alcohol (IPA) Is Used As Disinfectant In Pharmaceuticals?”, Pharmaguideline.Com <https://www.pharmaguideline.com/2013/11/why-70-isopropyl-alcohol-is-used-as-disinfectant.html?m=1> [Accessed 30 January 2020]
- “How Do I Make 70 Percent Isopropyl Alcohol?”, Sciencing <https://sciencing.com/how-do-i-make-70-percent-isopropyl-alcohol-12531559.html> [Accessed 30 January 2020]
- “The Difference Between Isopropyl Alcohol (IPA) 99% And 70%”, Lab Pro Inc. <https://labproinc.com/blog/chemicals-and-solvents-9/post/the-difference-between-isopropyl-alcohol-ipa-99-and-70-25> [Accessed 30 January 2020]
- “Using Alcohol To Disinfect Healthcare Surfaces – Reynard Health Supplies”, Reynardhealth.Com <https://reynardhealth.com/using-alcohol-to-disinfect-healthcare-surfaces/> [Accessed 30 January 2020]
- “Can 99% Isopropyl Be Diluted To 70%?”, Quora <https://www.quora.com/Can-99-Isopropyl-be-diluted-to-70> [Accessed 30 January 2020]
Craftiviti 
Hi Thanks for your tips to make diy home sanitizers. Can I use witch hazel instead of distilled water? Can I add in Aloe Vera gel ? If yes , what is your advise on the proportion . Thank you
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Hi Debbie! This is simply a guide to make 70% Isopropyl Alcohol from 99.8% Isopropyl Alcohol, using distilled or purified water is best for this purpose. If you’d like to DIY hand sanitizers, it depends on your personal preference whether you’d like to use and how much to use for witch hazel and aloe vera gel. For us, we use a 1:1 ratio for 70-99.8% Isopropyl Alcohol and aloe vera gel, which can be pretty drying so using hand lotion after is recommended.
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Thanks for the info on making my own hand sanitizer. I have 99% isopropyl alcohol and distilled water, but no aloe vera gel. Can I use a hand lotion like Aveeno Skin Relief as a stabilizer? And then would the proportions be the same as if I were using aloe vera? Thanks, rich
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Hi Rich, to be safe, it would be best to not mix them as alcohol can break down and combine with the molecules of whatever that’s inside ready-made hand lotion (which has more ingredients compared to pure aloe vera gel) etc, thus possibly destabilizing the product.
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Hi. May I know if we can use mineral or filtered water instead ? If i dont have distilled water.
Thank you
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Hi there! The best alternative to distilled water is osmosis purified water. Mineral water or filtered water may still contain bacteria and germs, or other contaminants.
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I bought 99% IPA isopropanol, and would like to use it to make 70% alcohol disinfectant. Is isopropanol same as isopropyl alcohol? Thank you very much!
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Hi Xiaoyan, Isopropanol is Isopropyl Alcohol 🙂
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This blog post is incorrect, because of hydrogen bonding between water and alcohol, volume is not conversed, only mass. You will not get 70% IPA.
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Hi Noxis,
Thanks so much for your comment! What is the correct way of getting 70% IPA then? Please share with us as we got our calculations from the referenced posts listed above 🙂
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Thanks for your openmindful and reply. It’s close enough I checked and you get 72% alcohol by volume (or 64% by weight) , and a total of 96.89ml. Still fine for sanitization purposes and your general audience, but using this type of math when it comes aqueous-alcoholic solution might lead to errors if trying to target a different percent.
It’s a highschool experiment where you mix say 50ml water + 50ml alcohol and then it turns out a few ml are “missing”, and doesn’t add up to 100ml.
https://www.youtube.com/results?search_query=+Mixing+Alcohol+and+Water++volume
https://en.wikipedia.org/wiki/Ethanol_(data_page)#Properties_of_aqueous_ethanol_solutions
Can use this calculator
https://planetcalc.com/1481/
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Hi, Can you make this formula simpler for us math impaired people. I have a half gallon of 99% isopropyl alcohol and I want to make it 70%. How much distilled water (in ounces) do I add to it?
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Hi Penney! Really sorry because we’re not familiar with the Imperial System as Malaysia uses a Metric System (meters and grams). Many of the formulas we’ve researched also uses the Metric System, so I’m not sure if it works the exact same with the Imperial System 🙏
Here’s a hopefully easier to understand, alternate formula I found on Quora (https://www.quora.com/Can-99-Isopropyl-be-diluted-to-70):
99ml IPA in 100ml total gives 99%
99ml IPA in Xml total gives 70%
Xml = (100mlx99%)/70%= 141.4ml
Thus, 41.4ml of distilled water has to be added to 100ml of 99%IPA make it into 70% IPA.
We also tried calculated in ounces for you.
Hopefully, this makes sense!
1/2 Gallon of 99% IPA = 63.36oz
To maintain 63.36 as 70% = (63.36/70)*100
Add 26.5oz distilled water
Total content will be 90.5oz
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Could I just take any size spray bottle, fill it about 3/4 full of 99% then the last 1/4 full of water? It wouldn’t be exact but would it be close enough to eyeball it like this to get close to 70% alcohol? I imagine this would be closer to 75% alcohol but all these numbers and mathematical equations make my head spin. I understand exact numbers would be important in more serious chemicals but to dilute 99% alcohol, can it be simple enough to eyeball the container one is using? 😁
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Hi there! Eyeballing is fine as long as you’re using this at home (not selling etc) only haha. It would better to use a beaker when you eyeball the recipe, though! So at least that would be a little more accurate 😉
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Can we just eyeball the container we’re using and do 3/4 full of alcohol and 1/4 full of water? I realize this would be closer to 75% alcohol but all these numbers and equations spin my head. 🥴 🤣
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Hi there! Eyeballing is fine as long as you’re using this at home (not selling etc) only cause we can’t guarantee that the solution is as effective haha. It would better to use a beaker when you eyeball the recipe, though! So at least that would be a little more accurate 😉
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