What's Actually in a Candle: Fill Weight, Fragrance Load and Why £8 Candles Smell of Nothing
Written by Heartman Fragrances, a hand-poured home fragrance workshop in the Cotswolds. Last updated August 2026.
Two candles sit on a shelf. One is £8, one is £21. They look roughly the same size.
The difference is not branding, and it is not markup. It is what is inside the glass — how much wax, how much fragrance, what kind of wax, and how long it was left to cure. None of that is printed on the label, which is exactly why the £8 candle can look like a bargain right up until you light it.
This is a guide to reading a candle properly. It applies to ours as much as anyone's.
1. The vessel is not the candle
The most common gap between what a candle looks like and what it is comes down to the jar.
Heavy-bottomed glass, a punt or false base pushed up into the vessel, a wide shallow shape that reads as generous on a shelf — all of these make a jar look larger than the wax it holds. None of it is dishonest, and none of it is hidden. It is simply that most people judge a candle by the size of the jar, and the jar is the cheapest part.
The number that matters is the fill weight, in grams, and it should be on the label or the product page. If a listing tells you the dimensions of the glass but not the weight of the wax, that omission is the answer.
Ours are 180g. Every one of our candles states it, including in the product name.
2. Fragrance load is the whole ballgame
Fragrance load is the percentage of the finished candle that is fragrance oil rather than wax. It is the single biggest driver of both scent throw and cost, because fragrance oil costs many times what wax does.
This is where a cheap candle is actually cheap. Reduce the load by a few percentage points and the margin improves dramatically, while the candle still smells of something in the shop, where you are sniffing it cold from six inches away. The difference only shows up in your living room, where a lightly fragranced candle produces a pleasant pool of scent about a metre across and nothing beyond it.
That is the honest explanation for the most common complaint about supermarket candles: I can only smell it if I'm right next to it. Nothing has gone wrong. There is simply not much fragrance in there.
A candle that fills a room has to carry enough oil to do it, and there is no way of faking that.
3. What the wax is made of
Most inexpensive candles are paraffin, a petroleum by-product. It is cheap, it holds fragrance well, and it has been the industry default for a century.
We use a rapeseed blend. Rapeseed is grown in the UK, it burns at a lower temperature than paraffin, and a cooler burn means the wax is consumed more slowly — which is part of why a smaller natural-wax candle can outlast a larger paraffin one.
We are deliberately not going to tell you that one wax is safe and another is dangerous. That claim gets made constantly in this industry and the evidence behind it is thinner than the confidence with which it is stated. What we will say is what we use, and why we chose it: it is grown here, it burns cooler and slower, and it carries our fragrances well.
4. Our fragrance oils
Our fragrance oils are supplied to us as phthalate free and paraben free.
It is worth being precise about what that does and does not mean, because this is territory where a lot of marketing overreaches.
Phthalates are a family of compounds used as solvents and plasticisers. Some of them — principally DEHP, DBP and BBP — have been studied for endocrine effects, and the European Chemicals Agency lists several as substances of very high concern on that basis. That research overwhelmingly concerns exposure through ingestion, skin contact and industrial settings, at concentrations far above anything associated with burning a scented candle at home. The compound historically used in fragrance, diethyl phthalate, is not among those classified for endocrine effects.
So: we are not going to tell you that other people's candles will disrupt your hormones. We have not seen evidence that supports that, and we would rather tell you the truth than frighten you into a purchase.
What we will tell you is that our supplier certifies these oils as free of phthalates and parabens, that this is one of the reasons they cost more, and that we would rather pay it. That is a statement about our product, and we can stand behind it.
5. Cure time
After pouring, wax and fragrance oil need time to bind. Pour a candle and light it the next day and it will smell weaker than the same candle left to cure for a fortnight.
Cure time costs a maker nothing but patience — and shelf space, and cash flow, which is precisely why volume production skips it. Ours are left to cure properly before they go anywhere. It is the least visible thing we do and one of the most consequential.
6. The wick
A wick has to be matched to the diameter of the vessel, the wax and the fragrance load. Too small and the candle tunnels, leaving a ring of unburnt wax down the sides. Too large and it smokes and burns hot.
Getting that right takes testing across every scent, because different fragrance oils behave differently in the same wax. It is unglamorous work and it is most of the difference between a candle that burns evenly to the edge and one that leaves a third of itself behind.
We use cotton wicks, tested per fragrance. If your candle is tunnelling regardless of brand, our guide on getting a full melt pool covers the fix.
What £21 actually buys
Set against an £8 supermarket candle, the arithmetic is straightforward:
- A stated fill weight of 180g, rather than a jar of unknown fill
- Enough fragrance oil to scent a whole room, not the corner it sits in
- Rapeseed blend wax, grown in the UK, burning cooler and slower than paraffin
- Fragrance oils certified phthalate and paraben free
- A proper cure before it ships
- A wick tested against that specific fragrance
- Approximately 30+ hours of burn time
- A reusable glass jar
Per hour of use, the gap narrows considerably. Per hour of use in a room that actually smells of something, it closes.
How to judge any candle, including ours
Four questions that cut through most marketing:
- What is the fill weight in grams? If it is not stated, ask. A maker proud of it will tell you.
- What is the wax? "Wax blend" without specifics usually means mostly paraffin.
- How far does the scent travel? Reviews answer this better than product copy. Look for people describing rooms rather than describing the jar.
- Does the burn time match the size? A large candle with a short stated burn time is usually burning hot, which means it will not last.
Frequently asked questions
Why are some candles so much cheaper?
Usually less wax, less fragrance oil, cheaper wax, and no cure time. The jar can stay the same size while all four of those are reduced, which is why price differences do not show up until you light it.
What does phthalate free mean?
Phthalates are compounds used as solvents and plasticisers, some of which are used in fragrance formulation. Phthalate free means the fragrance oil has been formulated without them. Our supplier certifies our oils as phthalate and paraben free.
Is rapeseed wax better than paraffin?
It burns cooler and slower, which generally means a longer burn from the same weight of wax, and it is grown in the UK rather than derived from petroleum. Paraffin holds fragrance well and is cheaper. We prefer rapeseed for the first two reasons.
Why does my candle not fill the room?
Most often fragrance load — there is not enough oil in it. Room size, draughts and open doorways also matter. A candle in an open-plan space will always seem weaker than the same candle in a closed room.
Where are Heartman candles made?
Hand-poured in small batches in the Cotswolds, in a rapeseed blend, with cotton wicks and fragrance oils certified free of phthalates and parabens.
Shop hand-poured candles
- Cedarwood & Amber Luxury Scented Candle — £21
- Warm Honey & Sandalwood Luxury Scented Candle — £21
- Vanilla & Patchouli Luxury Scented Candle — £21
- Vanilla & Jasmine Luxury Scented Candle — £21
Or browse the full candle collection.
Sources: European Chemicals Agency, Candidate List of substances of very high concern (echa.europa.eu). US National Institute of Environmental Health Sciences, Endocrine Disruptors (niehs.nih.gov). Both describe phthalate research generally; neither addresses scented candle emissions, and we have not represented them as doing so.
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