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How to balance top, heart and base notes

By Omer Siton, founder of PerfuMate · Updated

Start with roughly a third of the concentrate in top notes, half in the heart and a fifth in the base, then let the strip correct you. The shares are a starting point; what decides whether a perfume feels balanced is how long each material actually stays readable, and that is a fact about the material, not about the tier a chart filed it under.

What is the usual ratio of top, heart and base notes?

The figures passed around are somewhere near 20 to 30 percent top, 40 to 50 percent heart and 20 to 30 percent base, by mass of the concentrate. They are conventions, not chemistry. A citrus cologne can run half top notes and be right. An amber can run half base and be right. The split tells you where to put the first weights so that the opening, the middle hours and the drydown all have something to say. It does not tell you the perfume is balanced when the numbers land.

Two things make the shares lie. Materials differ enormously in strength, so 10 percent of a quiet material and 10 percent of a loud one are not the same 10 percent. And materials differ in how long they last, which is the real subject.

What is the 30/50/20 rule for perfume?

The 30/50/20 rule says a perfume's concentrate should be about 30 percent top notes, 50 percent heart notes and 20 percent base notes. It is a rule of thumb from hobby and blending guides, not a perfumery standard, and none of the guides that give it names a source.

The same numbers also circulate as the 50-30-20 rule, and the pages that use that name do not agree on what it means: some read it as 50 percent heart, 30 top and 20 base, the same split reordered, and others as 50 percent base, 30 heart and 20 top. None cites an origin. It is not the split of Jean Carles's classic method either. In his "A method of creation and perfumery", dated December 1961 in the copy The Perfumer's Apprentice publishes, the worked chypre is 25 percent top notes, 20 percent modifiers, his name for the middle group, and 55 percent bases, and Carles warns that a perfume of 20 percent bases, 30 percent modifiers and 50 percent top notes will lack tenacity (Carles, "A method of creation and perfumery").

As a first placement of weights the rule is harmless, and this page starts near it: the heart usually carries a large share and the base a fifth or more. As a target it misleads, because of what it counts. Its numbers are shares of mass, or of volume and drops in DIY guides, and a share of mass says nothing about loudness or lasting: 10 percent of Ethylene Brassylate, rated 2 out of 10 for impact, and 10 percent of Ambroxan, rated 7, are not the same base.

PerfuMate shows the real balance instead. It files each material by its strip life rather than its name, draws a formula's pyramid from the dilution-corrected grams, in five parts with top-heart and heart-base between the classic three, and can redraw it by how loud each line reads at each hour. Read that way, good formulas rarely look like 30/50/20. The worked skeleton further down this page, written as about 30, 45 and 25 parts by role, reads 22 percent top, 20 top-heart, 33 heart and 25 base, because pink pepper and linalool last 10 to 12 hours on a strip. PerfuMate's published accords run from the Eau de Cologne Accord at 80 percent top to the Classic Amber Accord at 94 percent base, with the Fougere Accord between them at 12.5 top, 48 heart and 40 base, and the untested starting formula for a vanilla perfume reads about 20, 18 and 62. Each is right for its idea.

What is the 3:1:1 rule for perfume?

There is no 3:1:1 rule in perfume making. 3-1-1 is the US airport rule for liquids in carry-on bags: each container holds 3.4 ounces (100 ml) or less, all of them fit in one quart-size bag, and each passenger carries one bag, so a perfume bottle over 100 ml goes in checked baggage (TSA, TSA FAQ).

Some fragrance blogs also use the name for a way of applying perfume: three sprays on pulse points, one on clothing and one on the chest or behind the ears. That is a habit, not a formula ratio. If you came for the balance of top, heart and base, it is the rule above, and a starting point rather than a law.

Which tier does a material belong to?

The marketing pyramid files materials by the kind of smell they have: citrus is top, flowers are heart, woods are base. The strip files them by the hours they last. When the two disagree, the strip wins, because the strip is what the wearer gets.

Hedione is the standard example. It smells like a heart note, a transparent jasmine, and it lasts on a blotter well into base-note hours. Iso E Super is another: filed as a wood, faint on a fresh strip, and still there the next day. Neither behaves like the tier its odour suggests, and a formula that dosed them by the pyramid rather than by the clock ends up with a heart that never leaves and a base that arrives before the opening has gone.

So the working rule is: read the substantivity figure, the hours a material stays readable on a strip, and file it by that. The odour family tells you what a material says. The hours tell you when.

Why does the opening disappear too fast?

Because top notes are mostly small molecules, they leave quickly, and a top share that looks generous on paper is gone in twenty minutes if nothing bridges it into the heart. The fix is rarely more top note. It is a material that lives in the gap between the opening and the middle: something that reads at minute ten and is still reading at hour one. Linalool does this in many florals, geraniol in roses, and a small dose of a long-lasting citrus effect in colognes. Bridging is the job most beginner formulas leave unfilled.

Why does the base take over?

Base materials are usually strong and always long-lasting, so a 20 percent base share of a strong material can be louder at hour two than the whole heart. If the drydown arrives early and flattens everything, the answer is not to cut the base tier as a block. Find the one line that is doing it, usually the strongest one, and halve it. Ambroxan at 2 percent and at 0.5 percent are two different perfumes, and only one of them lets the heart be heard.

A worked skeleton

A simple woody citrus, written in parts of the concentrate, with the tier assigned by strip life rather than by name:

Put it on a strip, date it, and read it at ten minutes, one hour, four hours and the next morning. If the bergamot is gone before the hedione has bloomed, raise the linalool. If the ambroxan is the whole story by hour four, halve it before touching anything else. Move one line at a time and keep the version that worked.

PerfuMate does the reading for you before the strip does. Every material on your shelf carries a strip-life figure, and the scent profile draws the formula over 0 to 24 hours in perceived impact, so a base that will drown the heart shows up in the chart before it shows up on skin. AI Studio composes only from the materials you own, handed your shelf and the catalog on every run and never trained on them.