How to Dose Essential Oils in a Formula

In connection with this previous post, today's subject details a bit about why precision is so important when making formulas for skincare products.

We're going to touch on something some DIY'ers hardly even give a thought  –  how to dose essential oils in a formula.

You: Seriously, Lise? We need lessons in counting drops?

Me: You mean you're measuring by the drop?

By the Drop? Please Stop.

A lot of people measure out essential oils by the drop when making a product for personal use (or in very small portions for friends and family).

It's totally understandable, "It's a super small batch and it's just a few drops."

Nevertheless, it is inaccurate to measure essential oils by the drop.

Why This Even Matters

You might be shaking your head by now and wondering why this matters at all.

I understand.

It really sounds a bit like overkill.

But picture this little scenario:
Let's say your family and friends have fallen in love with your product and demand is growing. Wonderful! You need to make bigger batches to accommodate everyone. Maybe you are also now considering selling your product through an online shop or at markets.

If your formula is not 100% precise, then you have no idea what percentage essential oil is in your product. If you upsize your formula by simply multiplying the drops of essential oil, you might exceed recommended dosage and your product may even cause harm to a customer.

As tempting as it might be to assume all essential oils weigh the same, this simply isn't so.


Because of a little something called density.

That Little Something Called Density

Every essential oil (and every carrier/fixed oil) has its own density. You can check out the nerdy details about what density is right here, but this picture kinds of explains it all.

See how the different oils in this graduated cylinder are 'layered' and not mixing? That's because each oil has a different density.

Even if you measure out the exact same volume of a few different oils and weigh each one, and even if you have been super-duper careful and poured up EXACTLY one teaspoon, the oils will not weigh the same unless they happen to have the same density.

This is why it is not accurate enough to measure essential oils (or any oils) by volume.

Ingredients – even single drops of essential oil – should always be measured by weight.

Putting it To the Test

Lorraine Dallmeier – Owner and Director of Formula Botanica – did her own comparison test. She measured the weight of 20 drops of several essential oils and recorded the results.

The difference in weight was a real eye-opener. Her test showed twenty drops weighed as low as 0.35 grams and as high as 1.05 grams.

Now, imagine upsizing your essential oil blend for a batch production by counting drops. That could be asking for a bit of trouble, couldn't it?

Today's tip: always measure by weight!

Read Lorraine's post and test results right here.

Which Scale

Since you ask: I use a jewelers scale for measuring minute amounts. Here's the one I have been using the last couple of years.

Do Tell

Are you a 'by the drop' person or are you measuring your EO's by weight?

Density Illustration courtesy of Wikimedia Commons


Signe said…
Well, I am "by the drop" person, but I totally understand and am aware of that knowledge that when you are making bigger batches and selling your products you need to measure everything by weight. But that photo you shared is very informative, thanks for that! I knew oils have differences, but I didn't realize that they can be so huge. That reminds me that when I'm making soap I need to mix oils properly before adding lye - otherwise my soap might not be safe to use.
María said…
I measure by the drop as well when making creams, as I make small batches (50-100 g). But for soap making, weighting oils in a precision scale is piece of cake.
I have to confess that I'm becoming lazy when I make soap, and I tend to use 10 ml essential oils/fragrances per 500 g of oil (not soap, oil), but that's just me.
Paula M said…
I have the exact same scale and it's the one I recommend to my students. Soaps always weight! Creams, I use drops because we make about 180g at a time. If I was selling a product I would use weight for everything.
LisaLise said…
@Signe - Ooh I'm glad to be of help! :)

@María - When I am doing something for personal use, I am also a by the drop person. All of my earlier scent blends were created by the drop. I'll bet what you call 'getting lazy' is mostly because you have been doing this so long you know exactly what you're doing. That's not lazy, that's experience! :)

@Paula M - Isn't it the greatest little scale? I do what you do as well - smaller batches for personal use, I'm a by the drop person. :)
J.S. Gates said…
Hi Lise,

Thank you for the informative post! I know that Essential oils should only be about 1% to 2% of the total product blend. I've started making 42g lotion bars in semi-medium batches, so blending 33 1/2 ounces of butter at a time and then pouring into mini molds. I add in 7g of essential oil to my 33 1/2 ounces of butter and I've had pretty great results thus far. Am I on the right track when it comes to weighting out my essential oils at an appropriate dilution? Or could I add a bit more essential oil to the overall batch?

Thank you!!
LisaLise said…
Hey there J.S.Gates - Thanks for your comment. It worries me a bit that you seem to be using both the metric and imperial measuring methods at the same time. Personally, this would confuse me to no end.

Let's do the math and have a look:
33,5 ounces equals 949,7 grams. Let's round up to 950 grams.
1 % of that is 9,5 grams.
You are adding 7 grams so it looks like you are keeping within the general safety limits with your essential oil amount.
Of course, the 1-2% max is a general rule. Some essential oils have a much lower recommended max dosage, so you'll have to look at the recommended percentages of each of the oils in your blend to be sure. Best of luck with it!
J.S. Gates said…
Hi Lise,

Thank you! Yes when I'm formulating I measure in ounces so when I was going through my notes last night I tried to convert everything to grams. Sorry I missed one and had you do all that math! But it looks like I should just convert over and measure in grams in the first place!
LisaLise said…
Thanks for clarifying J.S. Gates! :)
Katie said…
Hi, I am currently a by-the-dropper, but I do plan on purchasing a jewelry scale to convert to weight. My question is about diluting by weight vs. volume. It seems to me that most of the safety guidelines were developed in relation to volumes, so is it safe to assume that a 2% dilution by volume is the same as a 2% dilution by weight? Thank you!
LisaLise said…
HI Katie - A cosmetics formula is always measured by weight. It is not safe to assume 2% by volume is the same as 2% by weight- stick to weight and you will always know what you are working with. :)
Abe said…
Each Essential Oil has its own density and it matters a lot in cases such as making suppositories. I have a similar scale as the one shown here, but it isn't accurate enough and I've learned it the hard way!

The formula I follow contains among many E.O 10 mg of Pogostemon Cablin and 25mg of pistacia lentiscus. The scale should be precise to the milligram. Accuracy will determine whether the suppositories will represent a health hazard or be inefficient because it's used internally. Such small weights can actually be smaller than a single drop.
LisaLise said…
Hi Abe - you are correct in that every essential oil has its own density- Sorry to hear you had to learn this the hard way. Thanks for your comment.
Anonymous said…
My question is similar to Katies. I'm trying to go all weight but just want to make sure the dilution standards are the same for weight as they are for volume. I've worked with 2% dilution by volume before but if I'm now going by grams, should I aim for 2% dilution by weight?
LisaLise said…
Hi Anon - If a recommended dilution is listed in percent then it is by percent by weight. 2% of 100 grams is 2 grams. Hope this helps :)
Unknown said…
Hi Lise,

If I blend oils by volume, for example I pour a 5ml EO bottle onto a 100ml carrier oil bottle, can I scale up by simply mutiplying volumes? Why do I have to turn to weight? Thanks for your useful blog
LisaLise said…
Hi Anon - in theory you could stick to measuring in volume IF you are talking about small batch sizes (say, total 100 ml). It gets tricky when you want to scale up.
Every oil has its own density (oils don't weigh the same if measured purely by volume). If you measure out 100 ml of different oils and then weigh each one, you are going to get different weights. The difference is not enough to matter in a very small batch size, but matters a lot when you scale up.
Unknown said…
Hi there, I have been making lip balms for a while now and have always worked by drops. If every drop has a different density how do I start to convert the drop amounts to grams? For example if I use 70 drops of peppermint oil but that has a different density to 70 drops of lavender oil how do I work out what one drop should be in grams for each different oil? Hope this makes sense?
LisaLise said…
Hey there unknown - this is an excellent question. You will need a jewelry scale (one that can measure down to 2 digits). Place a small container on the scale and set it to 0. Then add your blend to the container as you normally would and check the weight. If you count the drops as you add, then check the resulting weight, you'll have an idea of how many drops makes X grams. Repeat the process a few times to be sure you are comfortable that your result is consistent.
Anonymous said…
Hello. Not sure if I’m too late in this thread for my question to be answered.
So say your making a 200oz hair care product with essential oils, dried herbs and powders. Is 10-12% of essential oils (10-15 different oils) too much for that large batch. Each would go in at 0.2g. Is that total percentage too much for a batch that size? Thank you so much.
LisaLise said…
HI Anon -- You are going to want to work exclusively in % when calculating - that's going to make everything easier.
Your question mentions grams, ounces and percentage and that's probably what is making it confusing. I'm not even completely sure of your question because there are 3 different forms of calculation.
You said you wanted to add 12% EO's to a 200 oz batch.
12% of 200 oz is 24 oz – that is a very high percentage of essential oils.
But you also said you want to add 0.2 g of each oil. If you have 10 oils at 0.2 g you have a total of 2 grams. 200 oz is equal to 5.670 grams. 2 grams added to that is 0.035%

Could you rephrase the question?

Anonymous said…
Hi Lise,
I see now how I was confusing to you and myself. So carrier oils are 65% herbs/powders 30% and essential oils 5%.
Is that too much essential oils for a formulation. And do you measure just how much carrier oils are being used the 65% or the total infused end product? What’s the max of EO for a formulation? I’ve read 2%.
I hope this is less confusing.
Thank you so much for your time as well. I really enjoyed your post.
LisaLise said…
Hi Anon - yes thanks that helped. 5% essential oils is a pretty high amount. I would probably stay at 2% or under. Tisserand Institute has all kinds of essential oil education you might enjoy-- you might want to check them out. I also teach a couple of cosmetic formulation courses there.
Unknown said…
Thanks for a very informative article @Lisalise. Very helpful. Is there a limit to what percentage of botanical extracts that can be used for hair care formulations using essential oils? For eg Amla powder? Thanks
LisaLise said…
Hi Unknown - Not knowing your specific formula, I'm going to have to give you a general answer. If you are using powdered botanicals such as Amla, it shouldn't affect how much EO you can add to the product and vice versa. Hope this helps!
Nicole said…
Hi there, thank you for your post! I'm confused. If I need to use 1% essential oil blend of a 10ml roller bottle then that equals to 0.1. Is this automatically 0.10grams? So should I use 0.10grams to 9ml grapeseed oil to make up my roller blend bottle?
LisaLise said…
Hi Nicole - Thanks for your question -- it is confusing dosing in smaller percentages to be sure! First of all, you need to go by weight all the way through for accuracy, so leave the ml out of the equation and go grams all the way.

For 10 g of product, you need 0.1 g of essential oil blend.
0.1 g EO's to 9.9 g oil gives you 1% EO's in oil.

Hope this helps!

K. said…
this blog has been very infomative. Hope is not too late to get my question answered. :)
ive been making my own bodyoil for skin tighting and its been working great bue now i want to scale up. I am counting about 10 drops right now of each oil and a carrier oil in 2 Oz bottle. How can i come up with the perfect formula for scaling? You also mentioned you tech this? How can we learn more.
Thanks for your time
LisaLise said…
Hey there K - your best bet is to make a batch as you normally do but weighing every ingredient and noting the weight of each one. (You'll need a jewelry scale that can measure down to 2 decimals for this). Make the batch a few times and note the weight of every ingredient each time. When you are comfortable that you have enough information then you should be able to convert the weights to percent. As soon as you have the percentage, it's easy to calculate any batch size - large or small. :)
Anonymous said…
hi lise,
i bought digital scale 0.1 grams to maximum of 500 grams for measuring essential oil, is it ok to use 0.1 grams digital scale?

and is it ok to measuring 0.6 grams liquid in that digital scale?
LisaLise said…
HI Anon -- You're going to need a scale that goes down an extra digit so you can measure hundredths of a gram - not just tenth of a gram. Your scale should be able to read down to: 0.01 g

Your scale should be able to weigh a single drop.
Unknown said…
Hi Lisa,

I hope this comment finds you in good spirit. I have just started with creating facial creams. using natural ingredients such as essential oils. Whats the relevant/recommended weight that one can use when adding the fixed and carrier oils on a 20 liter container or bucket full of raw coconut butter. I hope I'm making sense. Thank Nelly from South Africa
LisaLise said…
Hi Nelly -- This is going to depend on the dermal limits of each of the essential oils you are adding. This will need to be calculated first. If you were asking about the scale to use (your question can be understood a couple of ways) - then calculate the amount of essential oil you will need for the weight of your batch, weigh up the essential oils separately on an accurate scale, then add your essential oils to the batch.
Unknown said…
Hi Lisa. Thank you so much for your response.
Anonymous said…
Hi LisaLise,

Wow. Your patience with explaining this to us mere mortals out here is exemplary. The dilution ratios has been confusing for me, but reading through the comments with the same questions being asked 10 different ways, and your consistent, detailed responses really helped me to wrap my head around it.

The first step for me will now always be to make sure I'm measuring in the same system, to start! Then, as needed, calculate the conversion to grams. These 2 steps alone are a total game changer as the rest is fairly straightforward arithmetic (and there's always the internet if I need backup).

As an aside, what the heck are all the other experts doing out there, because, the ways you explain it, it's actually far less confusing than just about everyone else I've seen makes it out to be. Can you please teach them how to teach us lol.

It's clear that you have total understanding of the concepts here, and yet not a drop - or even a microgram - of condescension or annoyance comes through. In addition to being near miraculous, it is a very real gift to us all. As you know, making it accessible helps folks be safer and more effective. Thank you.

LisaLise said…
Hello Deeyh - Thank you so very much for your lovely words! I am truly grateful to hear this kind of comment, as I am a self-taught teacher, so your comment went straight to my heart. Enjoy your formulating journey!