# E-liquid: the entry guide for UK vapers > Composition, reading a label, formats and flavour families: the overview of e-liquid on the UK market, before going into the detail of any one bottle. A British shop wall lines up several hundred bottles. Ten millilitre bottles, hundred millilitre bottles, figures in milligrams, ratios written as fractions, mentions of salts, of nic shots, of shortfills. Nothing on the shelf explains the filing system, and two neighbouring bottles can be used in radically different ways. Understanding **e-liquid** starts with a map of the territory, well before any choice of flavour. ## An e-liquid rests on four ingredients An **e-liquid** is a mixture of propylene glycol, vegetable glycerine, food grade flavourings and, optionally, nicotine. There is no fifth family of ingredients, whatever the brand or the shelf position. All the variety on the market therefore comes from the proportions and from the aromatic composition, not from a difference in nature. Two bottles that taste nothing alike share exactly the same underlying architecture. British rules add a negative list to that picture. The Tobacco and Related Products Regulations 2016 ban certain ingredients in nicotine containing products, including colourings, caffeine and taurine, which is why you will not find them here even where they appear elsewhere. ## What each component does The four ingredients do not play the same role, and knowing their respective functions is enough to decode most labels. Each acts on one precise dimension of the result. Propylene glycol, usually shortened to PG, is the most fluid component of the mixture. It carries the aroma molecules and takes part in the sensation at the throat. A liquid rich in PG delivers flavour more sharply and produces less visible vapour, and it feeds the fine wicks of tight draw coils more easily. Vegetable glycerine, or VG, is thick and slightly sweet. It provides the volume of vapour and rounds the whole thing off. Its viscosity has a direct practical consequence: beyond a certain proportion it only circulates properly through coils with wide feeding channels. Flavourings represent a small share of the total volume but concentrate all the formulation work. They are food grade materials assembled into recipes that manufacturers often keep to themselves. Nicotine, finally, is optional, and its strength always appears on the bottle. ## Reading an e-liquid label in the UK Four pieces of information are enough to know whether a bottle suits your hardware. They all appear on the front or the side, in an order that varies between brands. The PG/VG ratio is written as two numbers, 50/50, 70/30, 30/70, and the first figure always names the propylene glycol. The nicotine strength appears in mg per ml, from zero up to the legal ceiling for ready to use bottles. The volume in millilitres governs the legal format of the product as much as how long it lasts. The mention of nicotine salts, where present, changes how a given strength is perceived. A fifth marker deserves a glance: the best before date or the batch number. A bottle open for a long time darkens and loses aromatic precision, which is not visible on a liquid that started dark. British packaging carries more than that. Nicotine containing products must be child-resistant and tamper evident, and must carry the required labelling and warnings, so a bottle with none of that is a bottle to leave alone. ## How the British catalogue is structured The shelf looks bewildering as long as you read it brand by brand. Read by format, it comes down to three families, each answering a regulatory constraint or a precise use. The 10 ml ready to vape bottle is the historic format and the simplest: a sealed bottle, a nicotine strength chosen at purchase, no handling at all. It makes up the bulk of the shelves in physical shops here. The shortfill is the British answer to the volume cap. Larger bottles are sold with no nicotine and deliberately filled only part way, the empty space being intended for one or more nic shots, those small nicotine bottles added and shaken in before use. That arrangement is not a vaper's trick but a direct consequence of the legal framework: above 10 ml, a bottle cannot be sold containing nicotine. Nicotine salts form the third family. Here nicotine appears in a salified form rather than as freebase. The difference is felt at the throat rather than in the hardware, which is why salts turn up mostly on small tight draw devices. ## Flavour families, the map of the shelf British retailers sort their offer into broad aromatic categories, near enough identical from one chain to the next. Six of them come back systematically, and recognising them shortens any search. Tobacco flavours reproduce a tobacco profile. Fruits cover the widest spectrum, from single fruit to complex blends. Menthol and ice play on a fresh sensation, with or without a dominant aromatic note. Desserts gather pastry, vanilla and caramel, sweets cover confectionery profiles, and drinks close the list, from cola to cocktail. That taxonomy is commercial, not technical. It makes the shelf readable but says nothing about the ratio or the strength, which remain the only two criteria of compatibility with your hardware. ## What frames the shelf in the United Kingdom Several distinct rules apply here, and confusing them keeps a good deal of shop counter folklore alive. Each one is worth knowing on its own terms. The Tobacco and Related Products Regulations 2016, administered by the MHRA, restrict nicotine strength to no more than 20 mg per ml, the volume of a nicotine containing refill container to 10 ml, and tank capacity to 2 ml. They also require every e-cigarette and e-liquid to be notified to the MHRA and published before it can be sold, which is what makes the shortfill and nic shot system the norm here. Sale of vaping products to anyone under 18 is prohibited. Separately, the sale and supply of single-use vapes has been illegal since 1 June 2025, a device counting as reusable only if it has a rechargeable battery, a refillable container and a coil the user can remove and replace, with refills and coils separately available to buy. One change is still ahead. Vaping Products Duty applies from 1 October 2026, charged at a flat rate on all vaping liquids whether or not they contain nicotine, alongside a duty stamps scheme covering retail packaging, with business registrations having opened on 1 April 2026. ## FAQ ### Can any liquid be used on any device? No, the ratio has to match the coil in use. A very thick liquid will not feed a fine wick properly, and a very fluid one tends to leak in hardware built for viscous mixtures. ### How long does a bottle keep? Closed and away from light, several months without difficulty. Once open, oxidation gradually shifts the colour and the taste, without making the product unusable. ### Why do some liquids foul coils faster? Recipes heavy in sweeteners leave a deposit on the wick as it heats. The effect is independent of the brand and concerns dessert and sweet profiles above all. ### Should a liquid rest before being vaped? Ready to use bottles can be used straight away. A freshly mixed shortfill gains from standing a few days so the flavours settle. ### Does a nicotine free liquid vape the same way? The behaviour of the hardware does not change, only the sensation at the throat differs. Ratio and flavour remain the criteria for choosing. ## Where to start on the e-liquid shelf Three decisions cut several hundred references down to a handful. The ratio first, dictated by your hardware. The strength second, within the legal ceiling. The flavour family last, the only ground where personal taste genuinely decides. A well chosen **e-liquid** comes down to that reading order: compatibility, then dosage, then pleasure. Everything else, formats, brands and ranges, is a way of dressing those three variables, as you can see in the way [a sub ohm tank ages its coils](/uk/vaporesso-itank-t/) according to what you put in it. If the hardware side is the unfamiliar part, the [guide to vape tanks](/uk/vape-tank-guide/) covers reservoirs, filling and maintenance, and the [Zeus family at GeekVape](/uk/zeus-vape-tank/) shows how coil values and liquid thickness are linked in practice. Keep one habit at the shelf: check the ratio against the range printed on your coil before the flavour tempts you, since that single check is what makes an **e-liquid** work as intended. This article is strictly informative and is written for adult vapers only. It is not a buying recommendation: depending on the reference, a vaping product contains nicotine, a substance that causes dependence. Nothing described here may be sold to under-18s in the United Kingdom.