Short answer
Top, middle and base notes describe the order in which a perfume's materials are noticed as it evaporates. Top notes are the most volatile and dominate the first minutes; middle (heart) notes form the main character over the next hours; base notes are the least volatile and remain longest. The pyramid is a useful simplification, not a law: evaporation is continuous, many materials contribute throughout, and the same material can play different roles in different formulas.
What the three layers mean
| Layer | Typical role | Common examples |
|---|---|---|
| Top notes | First impression; noticed within seconds, fade within minutes to an hour or so | Citrus oils, many herbal and aromatic oils, light esters and aldehydes |
| Middle (heart) notes | The main character; emerge as the top fades and last several hours | Most floral materials, spices, many green and fruity notes |
| Base notes | The drydown; last many hours, sometimes into the next day | Woods, resins, musks, vanilla, amber materials |
The physical basis is volatility: how readily a material evaporates at skin temperature. Small, light molecules tend to evaporate quickly; larger, heavier and more polar ones more slowly. Our perception of strength also matters — a powerful material present in a tiny amount can be noticed long after a weaker one that was present in more.
Why the pyramid is a simplification
- Evaporation is continuous. All materials begin evaporating at once, at different rates. There is no moment when the "top" ends and the "heart" begins.
- Materials interact. Low-volatility materials can slow the evaporation of others and change how a blend is perceived. That is the basis of fixation — see perfume fixatives explained.
- Some materials span the pyramid. Many modern aroma chemicals are used for effects across the whole wear, not in one layer.
- Marketing pyramids are not formulas. The notes printed on a perfume's description are evocative names chosen by the brand. They are not an ingredient list, and "notes" like "fresh air" or "cashmere" usually describe effects rather than single materials.
How perfumers use the pyramid in formulation
Treat the pyramid as a checklist, not a recipe. When a trial is weak at one stage, the pyramid helps you see where:
- A flat opening usually needs more volatile, diffusive materials — or the existing ones are buried under heavy materials at high levels.
- A hole after the opening — bright, then suddenly thin — suggests the heart is under-built or does not connect with the top.
- A short-lived perfume may lack base materials, or have them at levels too low to be perceptible.
- A heavy, muddy opening can mean base materials are overdosed and dominate from the start.
Evaluating at set time points makes these problems visible. How to evaluate a perfume formula suggests a schedule (opening, 30 minutes, a few hours, next day) and how to record what you notice at each.
Is there a "right" ratio of top to middle to base?
You will see ratios such as 30:50:20 or 20:30:50 recommended. They are not principles; perfumes that work exist across a wide range of proportions, and a formula's balance depends far more on which materials are used than on how the weight is split between layers. Strong materials at small percentages can dominate a layer. Start from the effect you want and evaluate, rather than from a target ratio.
Tagging materials by pyramid position
It is still useful to record a typical pyramid position for each material in your library — top, middle, base, or a combination — because it lets you see the structure of a formula at a glance and find candidates quickly. Record it as your own working classification, and revise it when a material surprises you. The same goes for fragrance families.
In RUŌOD Lab, each material can carry a fragrance pyramid position alongside its primary and secondary families, and its formula-composition report summarizes what your formulas smell of by pyramid and family — weighted by each material's pure active rather than by the weight of its solution, so a 10% dilution counts for a tenth of its row.
Summary for formulators
- Use the pyramid to diagnose structure, not to set proportions.
- Evaluate at several time points so each stage is judged.
- Record each material's typical position and revise it from experience.
- Remember that strength, not only volatility, decides what you notice.
The pyramid is one of several ideas that make up formulation; the others — accords, fixation, families, evaluation — are introduced in perfume formulation explained.
Whether a perfume should change through these layers at all is a design choice; see linear vs pyramidal fragrances. A simple way to place your own materials is to measure how long each lasts on a blotter; see measuring a material's tenacity.
Frequently asked questions
How long do top notes last?
Usually minutes to around an hour, but it depends on the material, its amount, the concentration of the perfume, and where and how it is applied.
Are base notes the same as fixatives?
Not exactly. Most fixatives are base materials, but a base note is defined by when it is noticed, while a fixative is defined by what it does to the rest of the blend.
Why do I smell the base notes immediately in some perfumes?
Many base materials are present and perceptible from the start; they simply outlast the others. Strong base materials at high levels are noticeable throughout.
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.