Can you use any e-liquid in any vape pen?

Not really. Almost any e-liquid will physically go into almost any refillable vape, but they will not all vape well. Thin, stronger liquids suit low-power pens and pod kits with a tighter draw. Thick, nicotine-free shortfills suit sub-ohm kits built for big vapour. Using the wrong one rarely breaks anything, but it can mean leaks, dry hits, harshness or a weak, unsatisfying vape.

If your kit uses prefilled pods, you can stop here: the e-liquid comes sealed in the pod. This guide is for refillable pods and tanks.

The four things to match

1. The VG/PG ratio of the e-liquid
2. The type of nicotine: nic salt, freebase or shortfill
3. How you draw: mouth-to-lung or direct-to-lung
4. The resistance of your coil

Get these lined up and almost any flavour will work.

VG/PG ratio: thick or thin

Every e-liquid is mostly a mix of two bases.

• PG (propylene glycol) is thin. It carries flavour well and gives a stronger throat hit.
• VG (vegetable glycerine) is thick. It gives a smoother feel and more vapour.

The ratio is printed on the bottle. Most brands put VG first, so 70/30 usually means 70% VG and 30% PG, but check the label, because some list PG first.

The rule of thumb is simple: the thicker the liquid, the bigger the coil and the more power it needs. A 50/50 liquid is thin enough to soak quickly through the small wicking holes of a pen or pod coil. A high VG liquid needs the larger wicking holes of a sub-ohm coil. Put thin liquid in a big coil and it tends to flood and leak. Put thick liquid in a small coil and it cannot wick fast enough, so you get dry, burnt-tasting puffs.

Nicotine type: nic salt, freebase or shortfill

Nic salts

Nic salts come in 10ml bottles, usually at 10mg or 20mg (20mg/ml is the UK legal maximum). They feel smoother on the throat than freebase nicotine at the same strength, which is why they suit compact pod kits and pens with a tighter, mouth-to-lung draw at low power.

They do not suit a powerful sub-ohm kit. Each puff produces far more vapour, so a strong nic salt can feel harsh and deliver much more nicotine than you intend. Our guides to which devices work best with nic salts and the best vape setups for nic salts go into detail.

Freebase nicotine

Freebase nicotine is the traditional form, also sold in 10ml bottles across a range of strengths and often at 50/50. It has a more noticeable throat hit than nic salts, which some people prefer. Like salts, it suits pens, pod kits and mouth-to-lung tanks.

Shortfills

Shortfills are nicotine-free, usually high VG, and come as 50ml or 100ml of liquid in a larger bottle with room to add a nicotine shot. A 10ml shot (often 18mg) in a 50ml shortfill gives you 60ml at about 3mg. Two shots in a 100ml gives about 120ml at roughly the same strength.

Shortfills are made for sub-ohm kits and tanks, where lower nicotine and lots of vapour go together.

How you draw: MTL or DTL

• Mouth-to-lung (MTL). You draw vapour into your mouth first, then inhale, much like a cigarette. The airflow is tight and the vapour is modest. Pens and most pod kits are built for this, and it pairs with nic salts and 50/50 freebase.
• Direct-to-lung (DTL). You breathe the vapour straight into your lungs in one go. The airflow is wide open and the vapour is dense. Sub-ohm kits are built for this, and it pairs with high VG shortfills at low strength.

Many pod kits now sit in between, with adjustable airflow and pods at more than one resistance, so one device can lean either way.

Coil resistance: the number on the coil

Resistance is measured in ohms and printed on the coil or pod.

• Higher resistance coils (around 0.8 ohm and up are common for MTL) run at lower power with a tighter draw. They suit thinner, stronger liquids such as nic salts and 50/50 freebase.
• Sub-ohm coils (below 1 ohm, and often well below) run at higher power with more airflow. They suit thick, high VG liquids at low nicotine.

Each coil also carries a recommended wattage range, so set your power inside it. If your device takes pods or coils at more than one resistance, changing the coil is the easiest way to suit a different liquid.

Quick pairing guide

Your device	E-liquid that suits it
Vape pen or compact pod kit	Nic salts or 50/50 freebase
Pod kit with a lower-resistance pod	Lower-strength nic salt or freebase
Sub-ohm kit or tank	Shortfills with a nicotine shot, or other high VG liquid

What happens if you get it wrong

• Nic salt or 50/50 in a sub-ohm tank: likely leaking through the large wicking holes, plus a harsh, strong hit with far more nicotine per puff.
• A shortfill in a pen or small pod: the thick liquid struggles to soak the wick, so you get weak vapour, dry hits and short coil life. At around 3mg it may also feel unsatisfying in an MTL kit.

Neither usually damages the device. Empty the pod or tank, fit a fresh coil, and refill with a liquid that suits it. If your vape still feels flat afterwards, work through why you are getting a weak hit.

Choosing a strength

Strength is personal, and the right one depends on the device as much as on you. If you are using nic salts, how to pick the right nic salt strength without overdoing it walks you through it.

Nicotine e-liquids are for adults aged 18 and over who smoke or used to smoke. Vaping is not risk-free, though the NHS says it is substantially less harmful than smoking. If you are using a vape to move away from smoking, the NHS Better Health quit smoking pages, your GP or a pharmacist can help.

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