Eau de parfum vs eau de toilette
The only thing separating them is how much aromatic material is in the bottle. The bands are conventions, and houses disagree about them constantly.
Eau de parfum is roughly 15–20% aromatic compound by weight and eau de toilette is roughly 5–15% — that percentage is the entire difference between them. Nothing else changes: not the formula, not the quality, not the ingredients. And no country defines either term in law, so a 14% eau de toilette and a 15% eau de parfum are the same perfume with different labels.
Eau de parfum and eau de toilette are not different products. They are the same thing at different dilutions — the aromatic compound is identical, and one bottle simply contains more of it than the other. A house can and often does sell both versions of a scent from a single formula.
The part worth knowing, because almost nobody says it: there is no legal definition of either term, in the US, the EU or anywhere else. The bands below are trade convention, and houses disagree about them by a wide margin. A 14% eau de toilette and a 15% eau de parfum are, chemically, the same strength with different words on the box. What the names reliably tell you is the order, not the number.
If you are making rather than buying, the practical question is what to put in the bottle — and the answer depends on something the labels never mention. These percentages are by weight, because that is how formulae are written. Measure the same recipe with a pipette and it comes out about 12% weaker, because aromatic materials are denser than alcohol. The dilution tool shows both figures side by side.
Every strength, in a 30 ml bottle
Computed on a fragrance oil of unspecified density. The last column is what the same bottle reads at if you measure by volume instead of by weight — the two conventions genuinely disagree, and no label tells you which one it meant.
Which to make
Lighter, sprayed more freely and cheaper to make — 5–15% is the widest band of the lot precisely because it is the one houses treat most loosely. The right choice for a citrus-led blend, which has nothing to gain from being concentrated.
The default for a first serious batch. Strong enough to last a working day, comfortable to spray, and the strength most people picture when they say "perfume".
Dabbed rather than sprayed. At 20%+ the alcohol starts struggling to hold everything in solution, so this is the strength most likely to haze — and the one that most rewards a long maceration.
What the strength actually changes
Eau de parfum runs 5–8 hours against 3–5 for eau de toilette. That is a real difference and a smaller one than people expect — a blend with no base notes will fade fast at any strength, and making it stronger only makes it louder while it lasts.
More compound means more material leaving your skin per minute, so a stronger dilution carries further. This is the difference people actually notice in a room, more than the length of wear — and it is why an extrait dabbed on the wrists reads as intimate despite being the strongest thing on the list.
Almost entirely the compound. An extrait at 25% uses about 6.5× the aromatic material of a cologne at 4% in the same bottle, and the alcohol costs a fraction of what the materials do. This is the whole of why strength and price track each other on a shop shelf.
Higher loads are harder for the alcohol to hold. Above roughly 20% a blend with resins or absolutes in it may haze, and that is a solubility limit rather than a mistake. Freezing and filtering it clears it permanently — the maceration guide covers the procedure.
An eau de toilette is not a cheaper formula, a simpler one or a worse one. It is the same compound with more alcohol in the bottle. Houses do sometimes reformulate between strengths — usually to rebalance an opening that behaves differently when diluted further — but the default is that they are the same perfume.
Choosing a strength for your own blend
A citrus-led formula concentrated to extrait strength is a loud version of something that still disappears by lunchtime. Bright blends want eau de toilette; base-heavy ones justify the higher loads.
18% is a good place to judge a formula from — strong enough to read properly, not so strong that a fault is hidden. Once you know the blend, dilute a sample down and see whether you prefer it lighter. Diluting is easy; concentrating is not.
If it fades too fast, the answer is base material or a fixative, not a higher percentage. Strength changes how loud it is, not when it stops.
More material per unit of alcohol means more has to settle. An extrait wants noticeably longer than the usual 28 days, and it is also the strength most likely to reward it.
Work out your own bottle
Pick a strength by name or by percentage and the tool gives you the compound and the alcohol in grams and millilitres at once.
Open the dilution tool →Print the note pyramid
Top, middle and base splits with the percentages that actually work. One page, free.
Estimates, not advice. Every figure on this page is computed from published reference values and standard measures, so your own inputs, equipment and conditions will move it. Nothing here is professional advice — talk to a qualified professional before acting on it.