Calculating an Allergen Concentration From a Fragrance Dose

Your fragrance supplier's spec sheet says Linalool is 3% of the fragrance oil. Your lotion uses that fragrance oil at 0.8% of the total formula. Neither of those two numbers is the number you need for your ingredient list or your CNF. You need a third number, and getting there is a two-step multiplication that a lot of makers either skip or do backwards.

Why you can't use either number alone

The 3% figure describes Linalool's share of the fragrance oil itself, not your finished product. The 0.8% figure describes how much fragrance oil you used, not how much Linalool that translates to. Neither one on its own tells a regulator, or you, whether you've crossed a disclosure threshold. You need to combine them.

The two-step calculation

Step one: convert both percentages to decimals.

• Linalool in fragrance oil: 3% becomes 0.03
• Fragrance oil in finished product: 0.8% becomes 0.008

Step two: multiply them together.

• 0.03 x 0.008 = 0.00024

Convert that back to a percentage: 0.00024 becomes 0.024%.

That's Linalool's real concentration in your finished product. Not 3%, not 0.8%, but 0.024%.

Checking that against the disclosure threshold

For a leave-on product, the fragrance allergen disclosure trigger is above 0.001%, which is the same as 10 ppm. Our calculated figure of 0.024% is well above 0.001%, so Linalool needs to be individually declared on both the CNF and the label, not left folded into a generic "Parfum" entry.

If this were a rinse-off product instead, like a shampoo or body wash, the trigger is higher: above 0.01% (100 ppm). The same 0.024% concentration would still clear that higher rinse-off threshold, so the product type matters when you're deciding whether a given calculated concentration actually triggers disclosure.

A second example where it does NOT trigger disclosure

Say a different allergen, Coumarin, makes up 0.5% of the same fragrance oil, still used at 0.8% of the formula.

• 0.5% becomes 0.005
• 0.005 x 0.008 = 0.00004
• Converted back: 0.004%

For a leave-on product, 0.004% is above the 0.001% leave-on threshold, so it still needs disclosure. But if this same fragrance oil were used in a rinse-off product at that same 0.8% usage rate, 0.004% falls below the 0.01% rinse-off threshold, and Coumarin would not need individual declaration in that rinse-off formula. Same ingredient, same fragrance dose, different outcome depending purely on product category and its corresponding threshold.

Table: quick reference for the math

Value	What it represents
Allergen % in fragrance oil	From supplier spec sheet or SDS
Fragrance oil % in finished formula	Your own formulation record
Multiply the two (as decimals)	Gives allergen's real concentration
Leave-on threshold	Above 0.001% (10 ppm) triggers disclosure
Rinse-off threshold	Above 0.01% (100 ppm) triggers disclosure

Where suppliers make this harder than it should be

Not every fragrance supplier hands you a full percentage breakdown of every allergen in their blend upfront. Some require a direct request for an allergen disclosure statement, since the full composition of a proprietary fragrance blend is often treated as confidential. If your supplier won't give you allergen percentages at all, that's worth pushing back on directly, because without those figures you genuinely cannot do this calculation or meet your disclosure obligations. A fragrance house selling into a market with mandatory allergen disclosure should expect this request and have a standard document ready for it.

Why this matters on a compressed timeline

Health Canada's fragrance allergen rules are rolling out in two waves. List 1 becomes mandatory on the CNF and the label on April 12, 2026, and List 2, an expanded list aligned with international allergen sets, becomes mandatory August 1, 2026. If you've got multiple fragranced SKUs, this multiplication needs to happen for every allergen, in every fragrance blend, across every product, twice, once for each list's ingredient set. It adds up fast if you're doing it by hand in a spreadsheet for a full product line.

Cosmetic Comply runs exactly this calculation automatically when it expands your fragrance blend into its components and carries the percentages through to the finished product, then checks the result against the relevant disclosure threshold for your product type. It's the kind of repetitive, error-prone math that's worth letting software handle so you can spend your attention on the formula itself.