# Diluting Isopropyl Alcohol

by Reece @ DIWith the sharp rise in Coatings (ie Optimum Opti-Coat, 22ple, etc.) that require a properly prepped surface we have been receiving more questions about how you dilute isopropyl alcohol (aka IPA) correctly. One of the most popular bottles you can pick up contains a ratio of 70/30 (Alcohol to Distilled Water), which can make the math a bit challenging if you want to dilute it. While it is generally okay to use it at the 70/30 ratio, many detailers prefer to dilute it down to a 50/50 (Alcohol to Distilled Water) ratio for optimal results. If you don’t want the boring details skip to the pictures and chart at the end of the article. For those who want to know the exact math behind the dilution we did our best to break it down very simply so please keep reading.

Using the following formula, .7 represents the 70% isopropyl alcohol you have and .5 represents the 50% we want to end up with. Therefore our formula to determine the appropriate percentage of alcohol is:

### .7x = .5 = .7143 or 71.43%

In conclusion x = 71.43 or 71.43%. So no matter what size bottle you have fill 71.43% of it with the 70/30 mix of isopropyl alcohol and the rest with water. If you want to determine the percentage of water just take the difference between the 71.43% and a full bottle which is represented by 1.

### 1 – .7143 = .2857 or 28.57%

Each bottle should then contain 28.57% distilled water no matter what size the bottle is. Below are the DI Accessories Isopropyl Alcohol and 2 bottle sizes of our DI Accessories Trigger Spray Bottles (22oz, and 32oz). Each bottle is marked with a black line to where this 28.57% of each bottle is located.

You are now going to want to fill each bottle to this line with water. We used some blue food coloring to help highlight the water for picture purposes.

After filling the bottle with 28.57% distilled water fill the rest of the bottle with a 70/30 isopropyl alcohol.

You now have a bottle of 50/50 isopropyl alcohol mix to help remove old protection and ensure you have a clean surface! You can also take a look at the table below for complete dilution information on multiple size bottles!

Diluting Isopropyl Alcohol (70/30 to 50/50) |
||||

Bottle Size |
% Of Water (Distilled) |
Ounces Of Water (Distilled) |
% Of Isopropyl Alcohol (70/30) |
Ounces Of Isopropyl Alcohol (70/30) |

8 Ounces | 28.57% | 2.3 Ounces | 71.43% | 5.7 Ounces |

12 Ounces | 28.57% | 3.4 Ounces | 71.43% | 8.6 Ounces |

16 Ounces | 28.57% | 4.6 Ounces | 71.43% | 11.4 Ounces |

22 Ounces | 28.57% | 6.3 Ounces | 71.43% | 15.7 Ounces |

32 Ounces | 28.57% | 9.1 Ounces | 71.43% | 22.9 Ounces |

64 Ounces | 28.57% | 18.3 Ounces | 71.43% | 45.7 Ounces |

128 Ounces | 28.57% | 36.6 Ounces | 71.43% | 91.4 Ounces |

Hopefully this information was helpful in answering some of your questions about diluting isopropyl alcohol!

LMAO!!!

Now you post this cheat sheet after I did the calculations myself last weekend…Thanks a lot. Seriously, this will help some folks for sure. Thanks for the article Reece, no matter how “late” it was. Just printed the chart out too. Thanks again.

Thank you SO much for this “cheat sheet” Reece – was actually wondering about this when it came time to applying 22ple – not as good at math as Brad W. is I guess. LOL

Am lucky enough to be a future student at the Esoteric Detail Academy – one LESS question to ask Todd!!!

Reece,

This is kind of funny, because it’s a fun use of algebra. It’s the right way to do it.

I used to estimate by figuring; 70% (alcohol) x some number = 50%. I’d arrive at ~.71 and .~29 for water, and then I’d round it to 70% and 30%.

Is water (distilled) the only thing that willmreduce the alcohol percentage? Specifically, will mixing aloe vera with rubbing alcohol (70%) result in a diluted alcohol percentage? If so, by how much? The mix I am supposed to do is 2 parts alcohol and 1 part aloe vera, but I need to end up with an end result of at least 60%. Do I need to start with a higher percentage (91-99) so the end result maintains at least 60 or will using 70 accomplish it as well?

In the equation, replace the .5 with the .6 It appears you are trying to make a hand sanitizer from the amount of alcohol you want to have. Yes, you need to add distill water then add the aloe vera to it. If you need to have a minimum of 60% IPA at the end, you need to start off with 100% IPA and not 70%. I thought the aloe vera was just to keep your skin soft.

Very helpful, I always looked for the highest percentage bottle of IPA on the shelf but still at 90% I never took into consideration that last 10% so I was really at about 60% water 40% IPA.

Brilliant!

I need a 60% alcohol. If I would mix 4 oz of 50% and 4 oz of 70% would it in essence be a 60% mixture?

Yes

yes, a 1to1 proportion of 70% and 50%=60%

In reducing 90% alcohol to 70%, would one add 20% distilled water for the reduction (90 – 20 = 70)?

um, no… 500 mL of 91% alcohol would need to be mixed with 150 mL distilled water to be a 70% solution. That’s a 10:3 ratio

HI clever people,

How do I find out if 2% of Isopropyl Alcohol in a mixture is still considered a dangerous good? There are no other flammable ingredients.

Basically, at what point does it become flammable? We have a few products with 2% ISO, and one with 3% and one with 5%. Need to know if we need to put flammable pictograms on them.

Thank you xoxoxo

Coming back on Serena Dempsey’s point from 2017: If I add 70 or 75% of water to 30% IPA/Ethanol/2-Propanol in any mixture to make home cleaning/window cleaning, table top cleaning liquids, will a flammability pictogram required to be shown on the bottle or SDS sheet? I don’t think that the mixture is anymore flammable at this percentages given the high content of water, however, one SDS Authoring software I used to make this mixture with came up with an automatic pictogram of ‘Flammable’ in the final SDS?? It did change the flash-point of the mixture as I played with % changes so the software is definitely good but want to be sure. If anyone knows the answer, this will be very helpful

Can I mix 50% and 70% together? Does it make the alcohol % stronger or dilute it? I’m wanting to use it in painting effects. I’m terrible with math. Thank you for any tips.

Hi. If you use equal quantities of 50% and 70%, you will have a 60%

Very useful DI. Thanks

Hi guys I’m back again with another question. I have a few 10oz bottles of 91% alcohol that I want to convert to 70%. How much distilled water do I need to add for each? please and thank you!

-Andrew

At what dilution level with water is a starting 70% rubbing alcohol no longer air flammable? I want to clean my carpets and I have a wood stove going. Don’t want to blow up.

I want 70% rubbing alcohol and I have 50% & 91% rubbing alcohol how do I mix to get what I want?

To make it easy use equal parts of alcohol. One 50% and one 91% then mix together. The math is 50 + 90 = 140. Then divide by 2 = 70% alcohol.

Do you have to dilute with water when you mix equal parts of 50% and 91% isopropyl alcohol?

No diluting will be necessary if mixing equal parts of 50% and 91%. You will end with a 70% ….. 70.5% alcohol.

Hi

Is there anyway to dilute 99.9% isopropyl alcohol in an aerosol can to 70% {if sprayed into a different container?

Likewise, reducing 99.9% isopropyl alcohol wipes to 70%..

I purchased these items by mistake and can’t return them..

I have 91%, could you please post a cheat sheet to dilute it to 70%? thanks!

To make it easy use equal parts of alcohol. One 50% and one 91% then mix together. The math is 50 + 90 = 140. Then divide by 2 = 70% alcohol.

We have IPA 99.0%, please help us how to dilute 1ltr. of IPA . We plan to use this because, alcohol 70% in any store is out of stocks. We are going to use IPA for desinfectant in production line as operator as well. Thank you.

I bought 91% Isopropyl Alcohol , but it’s too strong. I want to bring it down

to near 70%. How much tap water do I need to add? I have 25 ounces

of the 91% Isopropyl Alcohol. Thank you.

Okay.

How much tap water do I need to change 25 ounces of 91% Isopropyl Alcohol to 70% alcohol?

I can not find the math on this but I did see someone said about a 1/3 of a cup of distilled water for every 8 ounces. 1/3 cup = 2.66 ounces. I used ml then converted to ounces and came up with 2.48 ounces per 8 ounce. Do Not use tap water if you can get distilled water.

I have 99.9% isopropyl alcohol and want to create at 70% solution for rubbing alcohol. How much distilled water would I have to add to the 99.9 % isopropyl? Would it be the same calculation as for 91% isopropyl, 500 ml alcohol to 150 ml distilled water?

If you take out 150ml of the 500ml 99.9% alcohol (set it aside) add 150ml distilled water to your 500ml of 99.9% u would have a 70% bottle of alcohol. You would have 150ml left over. That is the easy/quick way. To do it the Right Way, here is the math:

(500ml X 99.9% alcohol)/70%

(499.5ml)/70% Do Not Smoke! Keep away from Open Flames when using Isopropyl alcohol.

713.57ml

713 – 500= 213ml

Since you already have 500ml alcohol, you need to add 213ml distilled water to make it a 70% solution.

If i can’t get distilled water, wht is next best way to dilute 99% alcohol to 70%.?

Distilled water doesn’t contain any impurities. Tap water and bottled water have mineral, that’s what gives it its flavor. If tap water is all you have then use it. It may leave streaks on glass but it will kill most viruses with 70%.

Thank you. Just found that Whole Foods sells Distilled water.

Most of the food store chains have distill water as well. some auto parts store will carry it too.

Please help. I have a 32oz (956ml) bottle of 99% alcohol that I would like to convert to 70%. How much water is needed?

thanks in advance

-Andrew

I meant 946ml sorry!

Make sure it 99% and not 91% that will make a difference. Please No Open Flames or Smoking around the Alcohol.

32oz. X 99% alcohol / 70%

31.68 pure alcohol divided by 70%

45.25oz.

45.25oz – 32oz = 13.25

Add 13.25oz distilled water to make 70% alcohol.

thank you so much for helping me. yes bottle says 99%

So if I want 60 % alcohol I use 60 % (99% isopropyl alcohol) + 40 % distilled water. Just trying to be clear. Thanks

Yes and No. I wouldn’t go below 62% alcohol blend to kill the virus. But for your question u would have about 59.5% blend of alcohol. The math: oz. X .99 alcohol divided by .60

I used Google and this is what I found:

DIY Hand Sanitizer:

2/3 cup rubbing alcohol of at least 70% alcohol concentration.

1/3 cup Aloe Vera

*When using rubbing alcohol with higher alcohol concentrations, add water to the mix.

Mix well and fill dispenser of choice

https://www.whas11.com/article/news/health/wipes-do-it-yourself-diy-sanitizer-hand-bleach-alcohol/417-c87a7bbe-5246-40ec-8ddd-d5c4d79b94a1

One more if you don’t mind lol? I have a spray bottle that has just about 12oz of 99% alcohol left in it. if I want to also make that 70% would the amount of water needed be 4.97oz?

thanks again

-Andrew

Yes 4.97oz. Great job! Also if you run out of 70% alcohol, you can use Hydrogen Peroxide.

Hydrogen peroxide does kill germs, including most viruses and bacteria.

A concentration of 3% hydrogen peroxide is an effective disinfectant typically found in stores.

Hydrogen peroxide can damage some surfaces and clothing, and is a more dangerous chemical than some disinfectants, so be cautious when handling it.

https://www.insider.com/does-hydrogen-peroxide-kill-germs-and-viruses

Hydrogen peroxide must be kept in a Dark container. Light breaks it down.

Thank you for confirming my math and letting me know about the 3% hydrogen peroxide alternative. I need to see if I can find some now!

It says the 3% can be diluted to 0.5% which is great to make whatever you have on hand last that much longer. Does anyone know if anything higher that 0.5% will work? I’m assuming so. I’m assuming using tap water would be fine to dilute the 3% down to 0.5%-1% to be safe?

Sorry, kills germs but not virus’…fact check please.

I have a question that I am hoping somebody here can help me with. I fall under the guidelines of “essential work” and need an alternate option for sanitizing my hands when soap and water isn’t available. I need to make hand sanitizer and I used the last bit of 99% alcohol that I had. However, I still have a 946 mL bottle of 70 percent. If I use the entire bottle of alcohol how much emollient can be added and still maintain the CDC’s recommended 60%-90% alcohol content? It’s already diluted to 70% so say I want to maintain 65 percent. Is the answer simply 5 percent or 47.3 mL of emollient that can be added? Or is my brain just done for the evening? Thank you

I used Google and this is what I found:

DIY Hand Sanitizer:

2/3 cup rubbing alcohol of at least 70% alcohol concentration.

1/3 cup Aloe Vera

*When using rubbing alcohol with higher alcohol concentrations, add water to the mix.

Mix well and fill dispenser of choice

https://www.whas11.com/article/news/health/wipes-do-it-yourself-diy-sanitizer-hand-bleach-alcohol/417-c87a7bbe-5246-40ec-8ddd-d5c4d79b94a1

Reply

I believe this article is WRONG. Using our formula you would need 99.9% alcohol to achieve the recommended 62 alcohol or above.

March 27, 2020 at 9:30 am

I used Google and this is what I found:

DIY Hand Sanitizer:

2/3 cup rubbing alcohol of at least 70% alcohol concentration.

1/3 cup Aloe Vera

*When using rubbing alcohol with higher alcohol concentrations, add water to the mix.

Mix well and fill dispenser of choice

https://www.whas11.com/article/news/health/wipes-do-it-yourself-diy-sanitizer-hand-bleach-alcohol/417-c87a7bbe-5246-40ec-8ddd-d5c4d79b94a1

Philter – I apologize for any confusion. The information in the article is correct as it is an article to help you dilute IPA for car detailing use when applying paint coatings. This original article was posted back in 2013, before this pandemic and is not designed to help you dilute down IPA to make hand sanitizer. If you are looking at making hand sanitizer, we do recommend following the CDC guidelines and other resources online that have better knowledge in that area.

I believe this forum about IPA is correct and true. I meant to say that the article I had posted about the Hand Sanitizer was INCORRECT. Sorry for the mix up.

Like Reece said, follow the CDC guidelines and other resources online that have better knowledge in that area. : )

https://www.cdc.gov/coronavirus/2019-ncov/infection-control/hcp-hand-sanitizer.html

After some discussion about this question with my engineer neighbor, he does think that adding the aloe to the alcohol will dilute the overall solution when considered “by volume”. The percentage of the alcohol itself remains the same but not the solution.

The CDC indicates the sanitizer needs to be at least 60% alcohol.

He did come calculations to achieve “60%… by volume”. He had first just given me the ratio calaculation (that’s 116 parts alcohol and 16 parts aloe) but since that’s cumbersome for my lame brain to know how to use, I asked him for actual measurements. As he needed to base that on the amount of alcohol to start Ihad him base it on using 8z of alcohol.

When using 70% alcohol as the base, for 8z alcohol add 2.5 tablespoons of aloe.

When using 91% alcohol as the base (that’s the type they have), for 8z alcohol add 3z aloe and 1z water (distilled is recommended). BTW, 1 fluid ounce = 2 tablespoons. He didn’t give me the parts ratio on this one and I didn’t think it was important enough to ask again. I’m sure he could provide it to you if you wanted to make other quantities.

Hope that helps and makes sure we are using an effective sanitizer with high enough alcohol content for our purpose of doing so.

If I use 16 cups. 99% alcohol ,16 tbs peroxide and 16 tsp glycerine how much water do I need to add to make a 80% mixture?

16 cups 99% alcohol = 128oz. 16 tbs peroxide = 8oz. 16 tbs glycerine or glycerol = 8oz.

128 X .99 divided by 80%

126.72 divided by 80%

158.4 oz. – 8oz peroxide – 8oz glycerine = 142.4

142.4 – 128 = 14.4

14.4oz. of water to be add

Hi how much water do I add to a bottle of 950 ml oh 99% isopropyl alcohol to convert to 70%

Thanks

(950 X 99%) divided by 70%

940.5 divided by 70%

1343.5 – 950 = 393.5

Add 393.5 ml distilled water to your 950 ml to = 70%

What is the ratio in ounces for 99.9 pure isopropanol to water, to make a 70% solution?

I would so appreciate the help, as all that math is making my head spin, and I don’t want to get this wrong.

Is it basically 70, 30? And would it matter if it weren’t a perfect measurement as long as I erred on the side of too much alcohol?

Yes, you are correct. 70/30 mix. And you have almost 100% alcohol. I would error on more alcohol.

CDC recommends the use of alcohol-based hand sanitizers with greater than 60% ETHANOL or 70% ISOPROPYL as the preferred form of hand hygiene in healthcare settings, based upon greater access to hand sanitizer. Hand washing with soap and water mechanically removes pathogens.

After some discussion about this question with my engineer neighbor, he does think that adding the aloe to the alcohol will dilute the overall solution when considered “by volume”. The percentage of the alcohol itself remains the same but not the solution.

The CDC indicates the sanitizer needs to be at least 60% alcohol.

He did come calculations to achieve “60%… by volume”. He had first just given me the ratio calaculation (that’s 116 parts alcohol and 16 parts aloe) but since that’s cumbersome for my lame brain to know how to use, I asked him for actual measurements. As he needed to base that on the amount of alcohol to start Ihad him base it on using 8z of alcohol.

When using 70% alcohol as the base, for 8z alcohol add 2.5 tablespoons of aloe.

When using 91% alcohol as the base (that’s the type they have), for 8z alcohol add 3z aloe and 1z water (distilled is recommended). BTW, 1 fluid ounce = 2 tablespoons. He didn’t give me the parts ratio on this one and I didn’t think it was important enough to ask again. I’m sure he could provide it to you if you wanted to make other quantities.

Hope that helps and makes sure we are using an effective sanitizer with high enough alcohol content for our purpose of doing so.

I came up with a 59% alcohol content with you add 1.5 oz aloe to 8oz of 70% alcohol.

Check to see what kind of Alcohol you are using. Ethanol or Isopropanol?

CDC recommends the use of alcohol-based hand sanitizers with greater than 60% ethanol or 70% isopropanol as the preferred form of hand hygiene in healthcare settings, based upon greater access to hand sanitizer.

Follow the CDC on hand sanitizer:

https://www.cdc.gov/coronavirus/2019-ncov/infection-control/hcp-hand-sanitizer.html

I’m here to help with the Math. I know nothing on making hand sanitizer.

Hi I have 4 bottles of 50% iso how can I mix them to a higher percentage. I am new at this and could use some help. Thank you.

You cant go up on the percentage unless you have a still. If u can find a friend with 4 bottles of 91% you mix them equally. Sorry I can’t help you.

I know distilled water is getting hard to find. Can you use boiled tap water to take the place of distilled water?

Boiled water is not distilled water however to make your own distilled water you do need to boil water. What you do is take a large pot fillet with about 8 cups of water, then put a smaller pot inside that, floating in the water… Take the lid of a large pot inverted on the top of the large pot putting ice inside the inverted lid and then turn the burner on to bring to a boil. As the water boils and create steam it will collect on the inside of the inverted lead then ripped into the smaller pot/bowl. That is your distilled water.

Will tap water negate the disinfectant properties of 70% alcohol, or it is an issue of how long it will keep? If you don’t care about surface finishes, but are just interested in disinfecting isn’t tap water good enough?

Thank you so very much. I will try it. Please stay safe and healthy.

Julie Cissne

I just finished the calculations to convert 91% IPA to 70% IPA when I saw this thread.

Does my figuring look right to you?

Given: 16oz bottle of 91% IPA.

Solve: How many ounces of distilled water do I add to get a 70% IPA?

.91(16 Original oz) = 14.56 oz 100%IPA

.70(X Total oz) = 14.56 oz 100%IPA

X Total oz = 14.56 oz 100%IPA / .70 = 20.8 Total oz

20.8 Total oz – 16 Original oz = 4.8 oz distilled H2O to be added

Answer: Add 4.8 oz distilled H2O

Yes. Add 4.8 oz of distilled water to the 16 oz of 91% alcohol to equal 70%.

I have 5 gallons of 99% alcohol and would like to cut it to 70%.

How much water would I need to add?

Thanks in advance

5 gallons = 640oz

640oz X 99% alcohol divided by 70%

633.6 divided by 70%

905.142 – 640 = 265oz of distilled water to be add to the 5 gallons. 2 gallons and 9oz water.

If you add 2 gallon water to the 5 gallons you will have a mixture of 70.7% + or – .01%

Thank you

I have 76% ISO Alchol how much in oz of distilled water do I need to add to make it 70%

How much Aloe would I add to the 76% ISO to make hand sanitizer?

Thank you in advance.

Its so close to 70% that you could just spray your hands with it. Idk how to make hand sanitizer… sorry.

Hi guys I’m back again with another question. I have a few 10oz bottles of 91% alcohol that I want to convert to 70%. How much distilled water do I need to add for each? please and thank you!

-Andrew

10oz X 91% divided by 70%

9.1 divided by 70%

13 – 9.1 = 3.9

Add 3.9oz of distilled water to get 70%

I have some 91% alcohol – would like to make a disinfecting spray……..is 70% what i need to dilute to so it is still effective or can you go lower? Only have about 10 ounces ….trying to make it last

I would not go lower than 70%

10oz X 91% divided by 70%

9.1oz divided by 70% = 13

13oz – 9.1 = 3.9oz

Add 3.9oz to the 10oz = 70%

Hi, I got 63% hand sanitizer that i would like to add 99% isopropyl alcohol to make final 70-75% modified sanitizer. What are the correct ratios to do this. Thank you.

How about mixing alcohol and hydrogen peroxide instead of water? Would that make a better disinfectant?

I have a 32 oz container of 95% ethanol I wish to convert to 70% how much distilled water do I add?

Hi. I would like to make some DIY disinfecting wipes. I understand that 70% isopropyl alcohol has already been diluted to have 70% ISO and 30% water. Would I just use pure 70% ispropyl alchol on my paper towels to make the wipes?

I watched a lot of Youtube videos and I saw people diluting it which doens’t make sense since, from my understanding, the alcohol is already diluted to the appropriate level for killing coronavirus if you buy it at 70%.

I have a 32oz of isopropyl alcohol, I want to convert into 70% alcohol. How much-distilled water should I use? I am challenged in math, so please tell me how many cups and tablespoons I should use to convert it. I read, 9.1 oz, but I don’t know what the .1 means. Would it be 1 cup and 3 tbls?

SO, I need some help here. I have need of of a certain minimum spec for isopropyl alcohol.

It needs to be 91% containing less the .003% by weight of non-volatile material. Assuming that the non-volatile material is water, does standard 91% isopropyl alcohol meet that? Thanks for your help.