Which CNF Range to Pick When Your Percent Sits on an Edge

Someone emailed us a spreadsheet last week with a formula where an ingredient landed at exactly 5.00%, and the Hotlist restriction for that ingredient capped it at 5%. Not 4.9%. Not 5.1%. Right on the line. They wanted to know which concentration range to select on the Cosmetic Notification Form, and honestly, it's a fair question, because the CNF asks for a range, not always a single number, and edge cases like this come up more than people expect.

Why the CNF uses ranges at all

The Cosmetic Notification Form lets you list an ingredient's concentration as either an exact figure or a concentration range, by INCI name. Ranges exist partly because formulas shift slightly batch to batch, and partly because it saves you from refiling every time a percentage moves by a fraction of a point. But a range is only useful if it's chosen honestly, meaning your actual formula, in every batch you plan to sell, genuinely falls within it.

The boundary problem

When your real concentration sits exactly on a restricted limit, the safe habit is to treat the limit as a hard ceiling and choose a range that does not extend past it, even if that means your range is narrower than you'd like. If the Hotlist restriction says an ingredient is limited to 5% and your formula uses exactly 5%, you do not want to select a range like "3% to 7%" just because it's a tidy bracket. That range implies some of your production could exceed the restriction, and if a compliance reviewer or Health Canada spot-checks it, that's a harder position to defend than a tighter, accurate range.

The conservative approach is:

1. Know your actual formula percentage precisely, not rounded.
2. Choose a range that sits entirely at or below the restricted limit.
3. If your formula varies batch to batch, make the range wide enough to cover real variation, but never wide enough to cross the ceiling.
4. If you genuinely cannot guarantee you'll stay under the limit across all batches, that's a formulation problem to fix before it's a filing problem.

Rounding is where people get into trouble

A common mistake is rounding 5.04% down to "5%" in casual notes, then filing a range that technically allows up to 5.5%. That's not the same thing. If your supplier's batch documentation shows any real variability, even something as small as plus or minus 0.1%, that variability needs to be reflected honestly in the range you select, not smoothed away.

The same logic runs in the other direction too. If a lower bound matters, for example an ingredient that only counts as a preservative function above a certain percentage, don't round up into a bracket that misrepresents what's actually in the bottle.

When to just recalculate the batch instead

Sometimes the cleanest fix isn't a clever range selection at all, it's reformulating the batch by a small amount so you're clearly under the limit with margin, say 4.5% instead of 5.0%. That gives you room for normal batch-to-batch variation without ever brushing the ceiling, and it makes the CNF range selection straightforward instead of a judgment call. If margin is available in your formula, it's usually worth taking it.

Remember the concentration isn't just the raw ingredient

This gets more complicated when the ingredient in question arrives via a supplier blend rather than being added directly. If a preservative blend is used at 1% in your formula and the restricted component makes up 4% of that blend, the real concentration in your finished product is 0.04%, not 4% and not 1%. Multiply the component's percentage within the blend by the blend's use level in your formula to get the true number, then apply the boundary logic above to that true number, not to either of the two percentages you started with.

A quick sanity table

Situation	Safer choice
Formula sits exactly at the Hotlist limit	Range capped at the limit, not straddling it
Batch variation is small and known	Range that comfortably contains all real batches, still under the limit
Ingredient comes from a blend	Recalculate the true finished-product percentage first
Formula regularly brushes the ceiling	Consider reformulating with margin instead of filing tight

This is exactly the kind of detail that's easy to get right in principle and wrong in a spreadsheet at 11pm. Cosmetic Comply's screening flags when a calculated concentration sits close to a Hotlist limit and shows the confidence behind that flag, and a real reviewer checks it before the filing goes out, which catches boundary cases like this before they turn into a CN number you have to amend later. If you're ever unsure how a specific Hotlist entry expects ranges to be reported, Health Canada's current CNF guidance is worth a direct check, since the exact expectations can be updated.