How to Test & Adjust the pH of Homemade Skincare Products
Learn why you should always test the pH level of your skincare products that contain water! We'll walk you through exactly how to adjust the pH level as well so your products are safe and gentle on your skin.
We’ve all heard about pH, but why is it important in skincare? PH is the measure of a substance's acidity or alkalinity and is rated on a scale of 0-14.
A product with a pH of 7 is neutral; if the pH is less than 7, the product is acidic.
If the substance is over 7, it is basic.
Your skin has a pH value, and it is naturally around a pH of 4.7-5.75.
Your skin being slightly acidic plays a vital role in keeping your skin healthy.
Why Does pH Matter?
If you’re not in science class, it can be a little confusing to know why pH matters when we’re clearly here to talk about skincare.
Well, the pH of your skincare products can change how they interact with skin and how well they work!
So your skin has a slightly low pH making it slightly acidic naturally.
Your skincare products having a lower pH that matches your skin’s natural pH means that they will work better with your skin.
Using a product that closely matches your skin in pH can help keep your skin happier!
Why Should You Measure pH in Skin Care Formulas?
A pH around 5 to 5.5 can be suitable for many skincare products, but it isn’t a universal target. The finished formula’s pH needs to suit both the intended product and skin application and the effective pH range of your preservative system.
Using products that are too high or too low in pH can cause irritation, flakiness, and inflammation.
Properly adjusting pH does not guarantee that a finished product will be non-irritating. If you have sensitive or reactive skin, patch test finished formulations and introduce new products cautiously — pH is only one part of skin tolerance, and natural ingredients aren’t automatically gentle.
You can also use products that have a neutral pH.
Your skin’s surface is naturally mildly acidic. This acidic environment supports your skin’s barrier function, helping it hold onto moisture, and supports the healthy balance of microorganisms that make up your skin’s microbiome. Disrupting this balance can cause your skin to have some serious problems!
pH Levels & Preservatives
If you’re making your own skincare products, you should also keep pH in mind for your preservatives.
Many preservatives are compatible with certain pH ranges that ensure they can offer a broad spectrum of protection against bacteria growth.
Many preservatives are best active at a lower pH. This means that if your product is too basic or the pH is too high, the preservative is not going to work as well, or at all.
Different preservatives have specific effective pH ranges. Check the supplier or manufacturer documentation for the exact preservative you’re using, and make sure the finished formula’s pH is compatible with that system as well as the intended product and skin application.
When to Measure pH
You should measure the pH of any homemade skincare product that contains water.
So any formula that contains water, hydrosols, or botanicals, should be pH tested including:
- Toners
- Lotions
- Creams
- Aftershave
- Cleansers
- Some Face Serum like this DIY Vitamin C Serum & DIY Hyaluronic Acid Serum
There is no need to test anhydrous products like body butter, sugar scrubs, salves and lip balm as they do not contain water.
Another important step in formulating is adding preservatives. Many natural preservatives such as sodium benzoate rely on lowering the pH of your formulation in order for it to work properly.
Sodium benzoate is one example of why preservative compatibility matters when choosing a target pH. Don’t assume that pH 5 to 5.5 will suit every preservative system; follow the supplier or manufacturer guidance for the specific system in your formula.
How to Measure pH in Skincare Recipes
You will need a sample of your product added to a sanitized glass beaker or container.
Formula Botanica recommends a sample of around 1-5 grams.
- Place your sample in a glass beaker
- Dilute with distilled water at a ratio of 10% product 90% water (note: some products like toners may not need to be diluted)
- Stir well then test your pH
There are two fairly simple ways to test the pH in skincare recipes. pH strips and pH meters. Both have their pros and cons but are fairly simple to use!
Using pH Strips to Measure pH
Let’s go over pH strips first. PH strips are small strips with a pH-sensitive area on one end that will change color based on the pH of the substance that it is exposed to.
This color is then compared to a color chart to obtain a pH reading. These strips are fairly inexpensive and very easy to use.
NOTE: Broad-range pH strips like these can test pH levels from 0-14. For skincare formulations, narrower-range strips can make the result easier to read because their color bands cover a smaller range. Choose a range that includes your formula’s target pH, and remember that strips still give an estimate rather than a perfectly precise reading.
They can be used on emulsions like creams and lotions too, though color-matching is harder on opaque or colored products. A properly calibrated meter with a suitable probe will usually give you a more reliable reading for those.
A couple of downsides to paper strips are that they can be slightly inaccurate.
They will deliver more of a rough estimate rather than an exact pH.
Another con to using pH strips is that you’ll likely need to use more than one strip per product, each time you adjust your formula, you’ll likely need a new pH reading.
Meaning that for each product, you’ll probably go through several strips.
Using a pH Meter to Measure pH
Another option for measuring pH is a pH meter. These meters can be pricey, but they can measure the exact pH of the product you’re making.
PH meters are a good option for anyone who is making products for others and needs precise measurements.
While you’ll only need one meter to read the pH of a product multiple times, they need proper care and storage along with precise calibration.
A pH meter may also need an emulsion probe to read pH levels on those products.
What tool you use to measure your products’ pH is ultimately up to you and what works best for your products!
How to Adjust pH Levels in Skincare Products
| Goal | Agent | Prep Ratio | Notes |
|---|---|---|---|
| Raise pH | Sodium bicarbonate | 10% agent : 90% distilled water | Use food, cosmetic, or pharmaceutical grade |
| Lower pH | Citric acid | 10% agent : 90% distilled water | Add gradually and test after each addition |
| Lower pH | Lactic acid | Dilute concentrated liquid to 10–40% | Handle concentrate carefully |
So now you know why pH matters and how to measure it, but how do you adjust it? You’ll first want to be sure that you’ve accurately tested the substance while it is at room temperature before making any changes.
How to Increase pH Levels
If your product’s pH level is low and you need to increase it, you can do so by adding small amounts of Sodium bicarbonate, or as we know it, baking soda.
Sodium bicarbonate has a pH of 8.4; this makes it great to add to products to increase pH to desired levels.
NOTE: You will need to mix together 10% Sodium bicarbonate and 90% distilled water before adding to your product. A good starting place would be 1 gram of sodium bicarbonate + 9 grams distilled water.
Using a jeweler's scale is the most accurate way to measure and weigh ingredients when formulating. It can measure very small quantities very effectively.
You may need to heat the mixture a bit to get the sodium bicarbonate and water mixed well.
Once your mixture is combined, you will simply add just a few drops to your product formulation and mix well.
Test the pH once again after adding to make sure it is within the range suitable for your product and compatible with your preservative system.
If you’re going to use Sodium bicarbonate in your skincare products to increase pH, we recommend using a food, cosmetic, or pharmaceutical grade version like this one; the household version typically has impurities in it that are not good to apply to skin.
How to Decrease pH Levels
In order to decrease pH, you can use citric acid or lactic acid. Citric acid is acidic, and the pH of a citric acid solution depends on its concentration. That’s why it should be diluted before use and added gradually while testing the formula’s pH. It can be found in powder or liquid form.
Adding small amounts of citric acid to a formulation can reduce pH levels; it is also a chelator and can bind any metal compound in the formulation to increase your preservative efficacy.
NOTE: You will need to mix together 10% citric acid and 90% distilled water before adding to your product. A good starting place would be 1 gram of citric acid + 9 grams distilled water.
Once your mixture is combined, you will simply add just a few drops to your product formulation and mix well.
Test the pH once again after adding to make sure it is within the range suitable for your product and compatible with your preservative system.
Lactic acid can be harder to come by than citric acid. It is typically sold as a liquid with a maximum concentration of 90% like this one.
Please keep in mind that the pH of Lactic acid is 2.43, making it very acidic.
At a high concentration, it can be very corrosive and should be worked with very carefully!
You will need to dilute it further with distilled water before adding it to your formulations. You can dilute it to 10%, 25% or 40%.
When used properly in a formulation, Lactic acid can be very moisturizing and work very well with your preservatives!
When you’re just starting out making your own skincare products or trying something new, it is imperative to remember to work in small batches at first and be prepared to start over!
Work in small increments when adjusting pH; you can always add more pH adjusting compounds if you didn’t add enough!
You should also measure the pH often, after each addition of any pH adjusting compound.
If you adjust your pH and it becomes too low, you risk ingredients in your formula degrading; so when adjusting pH, start low and go slow!
Do not use any home products such as regular baking soda, lemon juice, or vinegar to adjust your products’ pH!
Frequently Asked Questions About Skincare pH
Can I use lemon juice or vinegar to adjust the pH of my skincare products?
No — even though both are acidic, their exact acid concentration varies batch to batch, which makes it impossible to dose accurately or safely. Stick with a properly diluted cosmetic-grade acid like citric or lactic acid, measured and tested as you go.
Do I need to test the pH of oil-based products like balms or body butters?
No — anhydrous (water-free) products like body butters, sugar scrubs, salves, and lip balm don’t need pH testing, since pH only applies to water-containing formulas.
What pH should a homemade toner or facial serum be?
There isn’t one correct pH for every homemade toner or facial serum. The finished formula’s pH needs to suit the intended product and skin application as well as the preservative system being used. Check the supplier or manufacturer documentation for your specific preservative rather than automatically targeting pH 5 to 5.5.
Is a pH meter better than pH strips for testing skincare products?
A properly calibrated meter with a suitable probe gives a more precise reading and is worth it if you formulate often, especially for creams and lotions where strips are harder to read accurately. Narrower-range strips can be an inexpensive starting point, but they provide an estimate and may not be precise enough when your formula needs close pH control.
What happens if my skincare product's pH is too high or too low?
A pH that’s too far from skin’s natural range can cause irritation, flakiness, or inflammation with use — and if it’s too high, some preservatives (like sodium benzoate) may stop working effectively, putting the product at risk of contamination.
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