Essential Oils and Fragrance Oils: Usage, Dilution Ratios and Safety

Essential oils and fragrance oils are wonderful ingredients for soaps, body products, bath products, candles and home fragrance. They can transform a simple formulation into something that smells beautiful and enjoyable to use.

However, more fragrance does not necessarily mean a better product. Both essential oils and fragrance oils need to be used at appropriate concentrations, and the correct usage level depends on the type of product being made.

Understanding dilution, product categories and safety is an important part of responsible formulation.

Essential Oils vs Fragrance Oils

What are essential oils?

Essential oils are concentrated aromatic extracts obtained from plants. Depending on the plant, they may be obtained by steam distillation, expression or other extraction methods.

Examples include:

Lavender
Peppermint
Tea Tree
Lemon
Sweet Orange
Rosemary
Eucalyptus
Geranium
Frankincense
Lemongrass

Essential oils are highly concentrated and should generally not be applied undiluted to the skin.

Natural does not automatically mean risk-free. Essential oils contain many naturally occurring chemical constituents, and some can cause skin irritation, sensitisation or photosensitivity depending on the oil and concentration.

What are fragrance oils?

Fragrance oils are specially formulated aromatic mixtures used to give products a particular scent. They may contain a combination of natural and/or synthetic fragrance materials.

Fragrance oils are commonly used in:

Cold process soap
Melt and pour soap
Body products
Bath products
Candles
Wax melts
Room sprays
Reed diffusers

A fragrance oil designed for candles is not automatically suitable for skin-care products. Always check the supplier’s documentation and intended application.

Dilution of Essential Oils

When using essential oils in cosmetic products, the concentration should be calculated based on the total finished product, not simply the amount of carrier oil.

A commonly used starting point for many adult leave-on body products is around 1–2% essential oil, while some rinse-off products may tolerate higher concentrations.

However, these are general formulation guidelines — they are not universal safety limits. The individual essential oil must always be considered because some oils have much lower recommended maximum concentrations.

Basic Essential Oil Dilution Guide

Dilution	Essential oil per 100 g finished product
0.5%	0.5 g
1%	1 g
2%	2 g
3%	3 g
5%	5 g

Example: 100 g body lotion

For a 1% essential oil concentration:

100 g × 1% = 1 g essential oil

Therefore:

99 g lotion base
1 g essential oil blend

For a 2% concentration:

98 g lotion base
2 g essential oil blend

Example: 500 g product

At 1%:

500 g × 1% = 5 g essential oil

At 2%:

500 g × 2% = 10 g essential oil

What About Drops?

You will often see essential oil recipes written in drops rather than grams.

Drops can be useful for small personal blends, but they are not an exact measurement. Drop size varies according to the viscosity of the oil, the bottle and the dropper.

For professional cosmetic formulation, weighing essential oils with an accurate scale is preferable.

As a rough formulation guide, many formulators use approximately 20 drops per gram, but this should never be treated as an exact conversion.

For example, 1% in 100 g is 1 g, not automatically “20 drops” of every essential oil.

Essential Oil Safety

Different essential oils have different safety considerations.

1. Some essential oils can cause skin sensitisation

Repeated exposure to certain constituents can result in sensitisation. A person may tolerate an oil initially and develop a reaction after repeated exposure.

This is one reason why increasing the fragrance level simply because “it smells better” is not recommended.

2. Some citrus oils can be phototoxic

Certain expressed citrus oils can increase the skin’s sensitivity to ultraviolet light.

Phototoxicity depends on the particular oil and how it has been processed. Do not assume that every citrus essential oil has the same safety profile.

If using potentially phototoxic oils in leave-on products, check the supplier’s technical information and appropriate safety limits.

3. Essential oils should be diluted

Do not assume that applying an essential oil neat to the skin is safe because it is natural.

Essential oils are concentrated materials and should be properly diluted for topical use.

4. Keep essential oils away from the eyes

Avoid contact with the eyes and mucous membranes.

If an essential oil gets into the eyes, do not simply rinse with water and continue using the product. Seek appropriate first-aid guidance, particularly if irritation persists.

5. Extra care is needed for certain users

Special consideration may be required for:

Children
Babies
Pregnant or breastfeeding individuals
People with sensitive skin
People with known allergies
People with respiratory sensitivities
Pets

Use appropriate professional or medical advice where necessary.

Fragrance Oil Usage

Fragrance oils are different from essential oils because their maximum recommended concentration is generally determined by the specific fragrance formulation and its intended product category.

This is extremely important when making products for sale.

Do not assume that a fragrance oil can be used at 5% simply because another fragrance oil can.

The International Fragrance Association (IFRA) Standards provide maximum usage levels for certain fragrance materials according to the intended end use. IFRA explains that these limits are expressed as a percentage of the finished consumer product, not simply the fragrance concentrate.

Always Check the IFRA Certificate

When purchasing fragrance oil, ask your supplier for the relevant IFRA Certificate of Conformity or usage information.

The certificate should tell you the maximum recommended concentration for the relevant product category.

For example, a fragrance may have different permitted concentrations for different applications.

A fragrance suitable for a candle may have a completely different recommended level for a body lotion.

Never transfer the usage percentage from one product category to another.

IFRA also states that the most restrictive applicable ingredient can determine the maximum usage level for a fragrance formulation.

How Much Fragrance Oil Should I Use?

There is no single percentage that is correct for every fragrance oil.

As a general formulation starting point, many cosmetic formulators may begin around:

0.5–1% – lightly fragranced products
1–2% – moderate fragrance
2–3% – stronger fragrance

But these are starting points, not universal maximums.

The supplier’s IFRA documentation must always take priority.

If the IFRA documentation states that a particular fragrance can only be used at 1% in your intended product, you must not use 2% or 3%.

Essential Oils and Fragrance Oils in Soap

Cold process soap is different from leave-on skin products because the fragrance is used in a rinse-off product and the final formulation undergoes the soap-making process.

Even so, you should not simply choose a percentage based on what smells strongest.

For fragrance oils, check:

The manufacturer’s recommended usage rate
The IFRA certificate
The appropriate product category
Whether the fragrance is suitable for cold process soap
Whether it accelerates trace
Whether it discolours the soap
Whether it causes ricing or separation

Always perform a small test batch when using a new fragrance.

Fragrance Oil Calculation

The calculation is simple.

Finished product weight × fragrance percentage = fragrance required

For example, if you are making 1 kg of product and your supplier permits 2% fragrance:

1,000 g × 2% = 20 g fragrance oil

You would use:

980 g base
20 g fragrance oil

If the permitted usage rate is 1%:

1,000 g × 1% = 10 g fragrance oil

The same calculation can be used for essential oils.

Do Not Confuse “Maximum” With “Recommended”

An IFRA maximum is not necessarily the amount you need to use.

For example, if a fragrance is permitted at up to 5% for a particular application, you may find that 1.5–2% gives you enough fragrance for your finished product.

Using less fragrance can reduce cost and may produce a more pleasant product.

Always formulate for the intended result rather than automatically using the maximum permitted level.

Essential Oil Blends

When creating an essential oil blend, remember that the total blend concentration is what matters.

For example, if you want a 2% essential oil blend in a 100 g body product:

Lavender: 1 g
Sweet Orange: 0.5 g
Frankincense: 0.5 g

Total essential oils = 2 g

Therefore the finished product contains a 2% total essential oil concentration.

You should still check the individual safety considerations of every essential oil in the blend.

Can I Use Essential Oils and Fragrance Oils Together?

Yes, depending on the product and the suitability of the materials.

However, combining them does not mean you can ignore their individual safety considerations.

For example, if you use:

1% essential oil
1% fragrance oil

your total aromatic materials are 2%.

You still need to make sure that the fragrance oil is within its applicable IFRA limit and that the essential oil concentration is appropriate.

Important Safety Rules for Makers

When working with essential oils and fragrance oils:

Always:

✓ Read the supplier’s technical documentation
✓ Check the intended product application
✓ Check IFRA information for fragrance oils
✓ Weigh fragrance accurately
✓ Keep containers clearly labelled
✓ Store oils tightly closed and away from heat and direct sunlight
✓ Wear appropriate protective equipment when handling concentrated materials
✓ Keep oils away from children and pets
✓ Follow the supplier’s recommended usage rate
✓ Perform stability and compatibility testing on finished products

Never:

✗ Assume all essential oils are safe at the same concentration
✗ Assume all fragrance oils have the same usage rate
✗ Use candle fragrance in skincare without confirmation that it is suitable
✗ Apply concentrated essential oils directly to large areas of skin
✗ Exceed the supplier’s recommended or applicable maximum usage level
✗ Use an old or unidentified fragrance material
✗ Rely on drops as an exact professional measurement

Remember: Natural Does Not Mean Risk-Free

One of the most important lessons for new soap and cosmetic makers is that natural and safe are not interchangeable terms.

Essential oils are natural, highly concentrated materials with complex chemical compositions.

Fragrance oils may contain synthetic and natural fragrance materials that have also been assessed for particular applications.

Both can be used successfully and safely when they are correctly formulated.

The goal isn’t to use as much fragrance as possible — it is to create a product that smells wonderful while staying within appropriate safety limits.

A Simple Rule to Remember

Essential oils:
Check the individual oil, intended application and appropriate dilution.

Fragrance oils:
Check the supplier’s IFRA documentation and use the maximum permitted concentration for the specific finished product category.

For both:
Calculate the percentage based on the total finished product weight.

IFRA’s standards are updated as new safety information becomes available, so formulators should use current supplier documentation rather than relying on old recipes or generic percentage charts.

Final Thoughts – Essential Oils and Fragrance Oils: Usage, Dilution Ratios and Safety

Whether you are making handmade soap, body butter, lotion, bath salts, scrubs or home fragrance, responsible fragrance usage is an essential part of professional formulation.

At Fun with Soap, we believe that understanding your ingredients is just as important as making beautiful products.

Measure accurately. Check your documentation. Respect dilution rates. And remember — a little fragrance can go a long way.