What does the 'resistance' of a coil mean?

The resistance of an atomiser (coil) refers to the regulation of power (wattage or voltage from your battery/mod) to the coil. Resistance is measured in “Ohms” (Ω) and on coils is most commonly a number between 0.15Ω - 2.1Ω. A higher number/resistance usually means the coil is designed to allow less power through it, whereas a lower number/resistance usually means the coil is designed to allow more power through it. The coil should normally tell you its resistance and what power to use it on (for users with a variable wattage device), this will either be printed on the coil itself or on the box, usually in the form of a wattage range e.g. 1.5Ω: 10W-20W. The wattage range for a specific resistance may vary between different manufacturers, brands and models, due to factors such as material and type of wire used in the coil. Because of this, two completely different coils from different brands that have the same resistance won’t necessarily be able to handle the same amount of power, so it’s always worth checking what wattage is recommended for your coil. The more the wattage is increased, the more the user will experience a “hit” and increased vapour production. When increasing the wattage be mindful that using the coil on a wattage above the recommended wattage range will burn your coil out much quicker (or instantly if you go too much over). If you’re using the traditional “eGo” pen-style batteries you don’t need to worry about resistance and power too much, because these batteries output low, non-adjustable power, so different coil options won’t perform too differently. Lower resistances will feel slightly more powerful because the coil will let a bit more power through for more of a hit, and higher resistances will do the opposite. If you’re using a more modern battery/mod but it does not have adjustable wattage, your device will usually automatically read the resistance of your coil and output a wattage suitable for that coil. All batteries/mods have a minimum and maximum coil resistance that they can work on, known as an atomiser resistance range, e.g 0.15Ω - 2.0Ω. This is another factor to consider when choosing a coil to ensure you don’t end up using one that won’t work because it is not compatible with your device.

High amounts of power (realistically 15W and above) require a different style of vaping known as “Direct Lung” (DL). This is where the user inhales the vapour directly into the lungs, almost in one big deep breath, instead of drawing it into the mouth first (mouth-to-lung / MTL) like you would on a traditional cigarette. This is required because higher power vapourises e-liquid a lot quicker, meaning there is too much vapour to take into the mouth and so it must be inhaled in one long breath. This style of vaping can also be referred to as “sub ohm” vaping, because coils with a resistance below (sub) 1.0Ω (ohm) are usually the ones that take more power and require the DL style of vaping. Thicker e-liquids (liquids with more VG than PG) are better suited to DL because they are smoother on the throat and produce thicker clouds. Thinner liquids (with more PG than VG) may prove too harsh on the throat if used for DL vaping (and you will use them a lot quicker), so they are better suited to higher resistance coils for MTL vaping.