If you already vape and fancy building your own coils, you'll eventually run into two acronyms: RDA and RTA. Both are rebuildable atomisers, the part of your device that holds the coil, and both let you swap prebuilt coil heads for wire and cotton you wrap yourself. This guide covers what each one is, how they differ, and how to choose between them, plus what the current UK rules mean for anyone building their own.

Why customise your vape at all

There are three main reasons vapers move on from standard kits:

• More flavour from your e-liquid.
• More control over the power behind each puff.
• Bigger clouds, if that's what you're after.

Building your own coil and wick takes a bit of practice. It can feel fiddly the first few times, and mistakes are completely normal while you're learning, but most people get comfortable within a handful of builds.

If you're already into sub-ohm vaping, building your own coils for an RTA or RDA usually works out cheaper over time than buying prebuilt coil heads again and again, since you're paying for raw wire and cotton rather than a finished part.

What is an RTA vape

RTA stands for rebuildable tank atomiser. The main difference between an RTA and an RDA is the tank: an RTA holds a reservoir of e-liquid that feeds down onto your coil, so you're not dripping every few puffs. Tank capacity typically ranges from around 2ml up to 6ml or more depending on the make, and there's a huge range of RTAs on the market to suit different builds, budgets and styles.

The parts of an RTA

• Drip tip: the mouthpiece you draw on. Often made from Delrin to stay cool against your lips, though glass and ceramic versions handle heat better.
• Cap: unscrews from the top section so you can fill the tank, usually with a unicorn bottle or a small glass dripper.
• Chimney: sits between the tank and the top cap, directing vapour up to the drip tip.
• Glass tube: the reservoir itself, held in place by the top and deck sections.
• Chamber: screws down over the deck, posts, coil and wick. Juice holes in the chamber let liquid flow down to the wick, regulated by the vacuum in the glass tube.
• Deck and base: similar to an RDA deck, with posts for your coil legs, but no juice wells since the wick draws liquid from the tank instead. The base has airflow holes that feed air onto the coil.

RTA pros and cons

Pros: holds more e-liquid than an RDA's juice wells, so you're topping up less often, and it suits all-day vaping without carrying a dripper bottle around.

Cons: can leak if the wick isn't seated properly or if the tank's left on its side, and flavour is often described as slightly more muted than on an RDA.

What is an RDA vape

RDA stands for rebuildable dripping atomiser. Rather than a tank, an RDA has juice wells that you drip e-liquid into directly, onto the coil and wick.

The parts of an RDA

• Drip tip: same job as on an RTA, the mouthpiece.
• Cap: some RDAs have a "chuff cap", a removable top section that lets you drip without taking the whole cap off, or swap in a different colour cap for a bit of customisation.
• Posts: hold your coil legs in place. Post configurations vary a lot between decks, and some decks are postless.
• Deck: the base of the RDA, sometimes called the "build deck", where the posts sit.
• Juice wells: shallow reservoirs around the coil that hold a small amount of e-liquid between drips. Depth and size vary by deck.
• Coil: the heating element. Builds range from single coils up to quad or more, though multi-coil builds need more care.
• Wick: the cotton that draws liquid into the coil by capillary action, usually threaded through the coil itself.

RDA pros and cons

Pros: a shorter distance between vapour and your mouth generally means punchier flavour, and it's easy to switch e-liquid flavours by rinsing and re-dripping.

Cons: needs dripping more often since there's no tank, and juice wells can overflow if you drip too much in one go.

What about RDTAs

There's a third option worth knowing about: the RDTA, or rebuildable dripping tank atomiser. It's a hybrid, an open deck like an RDA's sitting above a tank section, so you get an RDA-style build with a reservoir underneath instead of juice wells. It's a reasonable middle ground if you like building on an open deck but want fewer refills, though RDTAs are less common on the market than either RTAs or RDAs.

MTL, DTL and sub-ohm: which style suits which atomiser

Most rebuildables get built with one of three vaping styles in mind:

• MTL (mouth-to-lung): draw vapour into your mouth first, then inhale, closer to a cigarette's draw. Suits higher-resistance builds and tighter airflow, and is common on smaller RTAs.
• DTL (direct-to-lung): inhale straight into your lungs. Suits lower-resistance, higher-wattage builds with wide open airflow, and is the usual style for sub-ohm RDAs and larger RTAs.
• Sub-ohm: any build under 1 ohm resistance, which draws more current from the battery and produces bigger vapour. Both RDAs and RTAs can be built sub-ohm, but it's worth reading the safety section below before you go there.

Neither atomiser type is locked to one style. It really comes down to how you build the coil and set the airflow, so it's worth deciding which draw you prefer before you settle on hardware.

Getting your numbers right: coil resistance and battery safety

This is the part that trips up most first-time builders, and it's also the part where getting it wrong actually matters.

Every extra coil you add to a build changes the final resistance. Two identical 1.0 ohm coils wired the way most dual-coil RDA decks are built give you a final resistance of 0.5 ohm, not 1.0 ohm. Three identical coils bring it down to a third, four coils to a quarter, and so on. That's Ohm's law at work, and it catches a lot of new builders off guard because the maths isn't intuitive until you've seen it happen.

Lower resistance means the battery has to supply more current, so an ohm reader isn't optional if you're building your own coils. Check the resistance every time before you fire the device, and again if you've bumped or adjusted the build.

Steam-engine.org has useful calculators if you want to check your numbers before you build, and it's worth watching a few coil-building videos to see the process before attempting your first one.

Choosing between an RTA and an RDA

A few things to think about before you commit to your first build:

• Deck space: pick a bigger deck for your first build. A cramped deck makes wrapping and positioning much harder than it needs to be.
• Materials: spend some time reading up on coil wire and wicking cotton before you buy, since the right material depends on the resistance and flavour you're after.
• Ohm reader: check your build's resistance every time, not just once.
• Battery safety: read up properly before you use any mod, mechanical or regulated.
• Tutorials: watching a few builds done before attempting your own saves a lot of wasted coils.

Once you've made your choice and got a feel for building, coil-building materials and tools are easy to find at most vape shops, and it's a skill that keeps paying for itself the more you use it.

Quick answers

Building your own coils takes a bit of patience at the start, but it's a genuinely useful skill once it clicks, and one of the few parts of vaping where the current UK rules on price and supply actually work in your favour.