# Sub-ohm vaping: how it works and staying safe > What sub-ohm vaping means, the hardware it needs, how Ohm's law applies, and the method for reading a cell datasheet before you trust a build. Dropping below one ohm opens the door to dense vapour and a warmer draw, and it brings a set of technical obligations that come with it. Misunderstood, **sub-ohm vaping** puts real strain on removable lithium ion cells. Understood properly, it is a stable and well documented style with a large following in Britain. This article sets out what the term actually covers, what hardware it requires, and the method for judging whether your own configuration is sound. ## What sub-ohm vaping actually means The name is literal. **Sub-ohm vaping** means running a coil whose electrical resistance sits below one ohm. Lower resistance lets more current flow at a given voltage, the coil heats faster and across a larger surface, and the result is more vapour and more warmth. British guides increasingly note that the strict definition has aged. The one ohm line was a meaningful frontier when it separated hobbyist rebuilds from everything else, whereas today a great many mainstream tanks ship with factory coils well under it. What the term really signals now is a style: direct to lung inhaling, open airflow, high glycerine liquid and higher output. That style is what carries the requirements. It is not the number itself that matters but the chain it sits in, from the coil through the device to the cells, and the fact that every link has to be sized for the one below it. ## The hardware sub-ohm vaping runs on A modern regulated device handles nearly all of the electrical work for you. It measures the resistance of the atomiser, refuses builds outside its published range, cuts off on short circuits and on over discharge, and holds output steady as the cells drain. Paired with a sub-ohm tank running a mesh coil and a wide airflow ring, that is the standard British setup and it needs no calculation from the user. Factory coils arrive with a manufacturer's recommended range printed on the box, and the device will not let you run them somewhere absurd. The device is the least risky part of the purchase, but it is not interchangeable. What separates one chassis from another for this style is set out in our comparison of [box mods for big clouds](/uk/choosing-a-box-mod-for-clouds/), where runtime and format matter far more than the headline output figure. ## Regulated devices against mechanical tubes The distinction is worth stating clearly because the two objects look superficially similar. A regulated device contains a chipset that stands between the cells and the coil. A mechanical tube contains a switch and nothing else, and it connects the cells directly to the atomiser. That means every protection a regulated device provides is absent. There is no resistance check, no short circuit cut off, no low voltage cut off, and no error message when something is wrong. The user supplies all of it, by calculation and by inspection, every single time. Mechanical devices remain a legitimate part of the hobby for people who genuinely understand them. They are not a starting point, and nothing in this guide should be read as encouragement to treat them as one. ## Ohm's law and reading a cell datasheet The relationship you need is the one between resistance, current and power. Lower the resistance and the current drawn rises. Raise the output demanded and the current rises again. As cells discharge their voltage falls, so they must supply more current to deliver the same power, which is why the hardest moment for a pair of cells is often near the end of a charge cycle. No safe figure is going to be published here, because the only figure that matters is the one belonging to the specific cell in your hand. What transfers instead is the method for finding it. Start by identifying the exact cell reference, then find the datasheet published by the cell manufacturer rather than by a retailer or a rewrapper. On that sheet, the continuous discharge rating is the value relevant to vaping: the current the cell can supply continuously under the manufacturer's stated test conditions. Pulse and maximum figures printed on commercial wraps follow no uniform test standard and should not be used as a reference. Capacity, quoted in milliampere hours, tells you about runtime and not about the ability to deliver current. High capacity cells commonly carry a modest continuous rating and the reverse is equally common, because the two properties pull against each other physically. Compare the current your configuration actually asks for against that published continuous rating, with margin. If you cannot calculate the current, or the manufacturer's datasheet cannot be found, that is the signal to take the setup to a specialist shop rather than to proceed on optimism. ## Cell habits that are not negotiable Some practices apply to every device with removable cells, whatever the brand. Cells run as a matched pair: same reference, ideally bought together, same age and the same history of charging and discharging. A new cell never goes in alongside a tired one. The wrap, the insulating plastic sleeve, has to be perfectly intact. Any tear near the positive terminal exposes the metal body and creates a short circuit risk, and a damaged wrap is replaced before use rather than repaired with tape. Transport happens in a rigid dedicated case, never loose in a pocket or a bag. Contact with keys or coins is enough to short a cell directly. Charging happens on an external charger built for the format and for lithium ion chemistry, following the maker's instructions, and cells showing corrosion, dents or heat damage are retired rather than nursed along. ## Liquid and strength on a British setup The style shapes the bottle as much as the bottle shapes the style. Dense aerosol at high output calls for glycerine heavy liquid, which is why British sub-ohm vapers buy shortfills and add their own nicotine shot rather than working from small ready mixed bottles. The legal frame explains the format. Nicotine containing liquid here is capped at 10 ml bottles and 20 mg/ml, so anything larger arrives without nicotine. In practice, high output setups sit well below that ceiling because a dense draw carries a great deal of aerosol, a point developed in our guide to [full VG e-liquid](/uk/full-vg-e-liquid-guide/). ## Frequently asked questions ### At what resistance does a coil count as sub-ohm? Below one ohm, by the literal definition. In everyday British use the term has widened to describe direct to lung vaping on open airflow generally, whatever the exact figure on the coil. ### Is a regulated device enough on its own? For the vast majority of vapers, yes. It handles resistance checking, short circuit protection and cut offs, which covers everything a factory coil setup demands of the electronics. ### Are mechanical tubes dangerous? They remove every automatic protection and hand the responsibility to the user. They demand a working command of Ohm's law and of cell datasheets, and they are not suitable for beginners. ### What nicotine strength suits this style? Conventionally a modest one, well under the 20 mg/ml legal ceiling, because a high output coil delivers a lot of aerosol per draw and a strong mix quickly becomes uncomfortable. ### How do I know a cell suits my setup? By comparing the current your configuration draws against the continuous discharge rating on the cell manufacturer's own datasheet, with margin, rather than against the figure on the wrap. ## What to take away before dropping below one ohm The style is not difficult, it is demanding in a specific place. Everything above the cells is handled for you by a regulated device and a factory coil, and the part that stays yours is the pair of lithium ion cells feeding the whole chain. Treat those cells as components with published specifications rather than as consumables. Know their reference, read their datasheet, keep them matched, keep the wraps intact, carry them in a case and charge them properly. Retire anything damaged instead of hoping. Once those habits are in place, **sub-ohm vaping** rewards the effort with volume and warmth that no small pod delivers, and the settings side becomes a matter of patient adjustment rather than risk, as our walkthrough of [wattage and airflow settings](/uk/wattage-airflow-vape-settings/) sets out. Approach **sub-ohm vaping** in that order, cells first and hardware second, and there is nothing hazardous about it. Editorial content for adult readers only. Vaping products usually contain nicotine, a substance that causes addiction. Not for sale to under-18s in the United Kingdom. This article is not a buying recommendation.