Short answer
To refine a perfume formula without losing track, change one thing per version, decide in advance how the formula's total will be kept, use step sizes proportional to each material's strength, and record every change with its reason. Make each change as a new numbered version rather than editing the old one, compare it side by side with the version before, and keep the versions you reject — they tell you what not to try again.
Decide what the problem is first
A change is only useful if it addresses a specific observation. Before touching the formula, write down what the last evaluation found, as precisely as you can: "the opening is thin for the first ten minutes", "the heart reads as soapy at 2 hours", "the drydown is gone by 6 hours". The time point tells you where to look; how to evaluate a perfume formula explains why consistent time points matter.
One variable at a time
Change one material, or one deliberate group that serves a single purpose, per version. If you increase a citrus, add a green note and reduce a musk in the same trial, and the result is better, you cannot know which change helped or whether one of them made things worse. In early development, larger multi-change jumps can be useful to explore quickly — but label them as exploration, and return to single changes to refine.
Keeping the total
Adding to one row changes every row's share of the formula. Decide which approach you are using:
- Compensate. Every addition is balanced by a removal from a named row, so the total stays at 100% (or 1000 parts). The trial changes exactly two things, and both are visible.
- Renormalize. Add or remove freely, then rescale the whole formula back to 100%. Every other material falls or rises slightly in proportion. This is fine as long as you remember it happened.
The arithmetic of renormalizing is worked through in parts per thousand in perfume formulas. Note that rescaling the whole formula to a new batch size is not an adjustment at all — the proportions do not change. That is covered separately in how to scale a perfume formula.
Step sizes
A sensible step depends on how strong the material is and how much is already there:
- Major components (10% and above): steps of 10–20% of their current amount are usually perceptible without being drastic.
- Modifiers (around 0.5–5%): steps of 25–50% of their current amount.
- Powerful trace materials: a doubling or halving may be needed to notice anything — or may be far too much. Work with dilutions so the amounts stay weighable.
These are working conventions, not rules. A useful technique when the right amount is unclear is to make two or three versions at once that bracket the change (for example, a material at its current level, ×1.5 and ×2) and compare them together.
Changing a dilution
Switching a material from a 10% solution to a 1% one is a common adjustment, and a common source of confusion. If you want the same amount of the material in the formula, you must weigh ten times as much solution — which adds solvent and changes every other row's share. If you keep the weight the same, the material drops to a tenth. Decide which you mean before you change it; formula %, absolute % and relative % explains the options.
The three ways to make the switch — keep the weight, keep the pure material, or keep both by exchanging solvent — are worked with numbers in how to change a material's dilution in a formula.
Reformulating: replacing a material
Sometimes a material must go — it is discontinued, too expensive, or restricted at the level you need. Replacing it is a series of adjustments:
- Identify what the material contributes, at which time points.
- Shortlist candidates of similar family and volatility, and smell them in dilution against the original.
- Swap at an equivalent effect, not an equivalent weight — strengths differ.
- Compare the new version with the old at every time point, and adjust supporting materials.
- Recheck restrictions for the new material on a finished-product basis.
If the replacement is driven by a supplier change rather than a choice, documenting raw material supplier changes covers what to record.
Record every change
- New version number; the old one stays readable.
- What changed: material, old amount, new amount, dilution.
- Why: the observation that prompted it.
- Result: the evaluation of the new version, compared with the old.
- Decision: keep, reject, or explore further.
Version numbering, statuses and locking approved formulas are covered in perfume formula version control. When the versions are being sent to a client or panel for feedback, see how to track fragrance mods and samples. In RUŌOD Lab, duplicating a formula creates a named, marked copy to work on while the original stays as it was, and edits are undoable across the app if a change goes wrong. The broader development cycle is described in the perfume formulation guide.
Frequently asked questions
How many versions does a perfume usually take?
It varies enormously — from a handful for a simple formula to dozens or more for a demanding brief. The number matters less than whether each version taught you something.
Should I keep rejected versions?
Yes. A rejected version records an idea that did not work, which saves you from trying it again, and sometimes a later problem is solved by returning to it.
Written and reviewed by the RUŌOD Lab team. This article is general education about perfume formulation and record-keeping; it is not legal, regulatory or safety advice, and the examples are illustrations, not validated commercial formulas. How we write and check these guides.