A Practical Guide to Vape Shortfills in the UK

A 50ml bottle with a visible gap at the top is not underfilled by mistake. That space is there for a nicotine shot, and knowing how to use it makes shortfills one of the most flexible ways to buy e-liquid. This guide to vape shortfills explains what to look for before adding anything, from nicotine calculations and VG/PG ratios to choosing a bottle that suits your kit.

What is a vape shortfill?

A shortfill is a larger bottle of nicotine-free e-liquid that has been deliberately filled below its full capacity. The remaining space lets you add one or more nicotine shots without needing a separate empty bottle in most cases.

In the UK, nicotine-containing e-liquid is commonly sold in 10ml bottles. Shortfills give regular vapers the option to buy larger quantities of their preferred flavour, then set the final nicotine strength themselves. A typical example is 50ml of e-liquid supplied in a 60ml bottle. Add one 10ml nicotine shot and you have 60ml of ready-to-vape liquid.

Shortfills are especially popular with sub-ohm vapers using refillable tanks, higher-powered kits and larger pod systems. These devices tend to use more liquid than a compact mouth-to-lung pod kit, so a 50ml or 100ml bottle can be more convenient than buying several small bottles.

Choosing a shortfill for your vape kit

The flavour name is only one part of the choice. Before filling your tank, check the VG/PG ratio and the type of coil you use. These two details have a bigger effect on how the liquid performs in your device.

Higher-VG shortfills for sub-ohm vaping

Most shortfills are high VG, often 70VG/30PG. VG, or vegetable glycerine, is thicker and produces denser vapour. It is generally suited to sub-ohm tanks, high-wattage kits and direct-to-lung vaping, where larger coil openings can handle thicker e-liquid.

A 70VG shortfill can offer full flavour and generous vapour, but it is not automatically the right choice for every device. Small pod coils and tight mouth-to-lung kits may struggle to wick thicker liquid efficiently. This can lead to dry hits, reduced coil life or inconsistent performance.

Balanced blends for pods and MTL devices

If you use a lower-powered pod kit or a mouth-to-lung tank, look for a 50VG/50PG shortfill where available. A balanced blend is thinner, making it more suitable for smaller coil ports. It also usually gives a more pronounced throat hit than high-VG liquid at the same nicotine level.

Many compact pod users prefer nic salts in 10ml bottles because they are already available in higher strengths and are easy to refill. However, a lower-VG shortfill can be a practical option if you vape at low nicotine strength and want a larger bottle format.

How nicotine shots work

A nicotine shot is a small bottle of unflavoured nicotine liquid, usually 10ml, designed to mix with a nicotine-free shortfill. They are available in different strengths and blend types, including freebase nicotine and nic salt shots.

The final strength depends on three things: the nicotine strength of the shot, the amount you add and the total volume after mixing. A standard 10ml 18mg nicotine shot contains 180mg of nicotine in total. When it is added to 50ml of nicotine-free liquid, the finished 60ml bottle works out at 3mg/ml.

The useful calculation is:

Nicotine strength of the shot × amount of shot added ÷ final total volume = final nicotine strength

For example, 10ml of 18mg nicotine shot added to 50ml of shortfill gives 3mg in 60ml. Two 10ml 18mg shots added to 100ml of shortfill creates 120ml at 3mg.

Do not assume every shortfill is designed for the same result. A 50ml shortfill in a 60ml bottle normally has space for one shot. Adding two shots will overfill it unless you decant some liquid into a spare bottle. It also will not produce 6mg - it would make roughly 5.1mg across 70ml. Always check the bottle capacity and the manufacturer’s suggested mix before buying extra shots.

Freebase or nic salt shots?

Freebase nicotine shots are a familiar choice for vapers who want a clearer throat hit, particularly at lower strengths in a sub-ohm tank. Nic salt shots are smoother, which can suit those who find freebase nicotine harsh. The right option comes down to personal preference, your device and the final strength you are aiming for.

At 3mg, the difference can be subtle for some vapers. If you are moving from nic salt pod liquids to a lower-strength shortfill, a nic salt shot may make the transition feel more comfortable. If you are unsure, start with the type you already vape successfully rather than changing flavour, hardware and nicotine format all at once.

How to mix a shortfill properly

Mixing a shortfill takes only a few minutes, but nicotine is a substance that needs sensible handling. Keep bottles away from children and pets, avoid getting liquid on your skin and wash your hands if there is a spill. Only use nicotine shots and e-liquid intended for vaping.

First, remove the shortfill cap and nozzle carefully. Most bottles have a removable nib that can be lifted with a suitable bottle opener or eased out with care. Add the nicotine shot slowly, then replace the nozzle and cap firmly. Leave a little room in the bottle if possible, as this makes shaking easier.

Shake the bottle thoroughly for at least a minute. Turn it upside down several times to help combine liquid around the cap and nozzle. The e-liquid can usually be used straight away, especially if it is a fruit, ice or bar-style flavour, but a short rest can help the mix settle.

If your bottle is filled to the top after adding a shot, wipe the outside before opening it again. Pressurised bottles can spill when the nozzle is removed too quickly, particularly after being carried in a bag or left in a warm place.

Does a shortfill need steeping?

Steeping means leaving e-liquid to rest so the ingredients can blend and the flavour can develop. It is not always necessary, and it depends heavily on the recipe.

Fruit, menthol, ice and fizzy drink profiles are often good to vape shortly after mixing. Dessert, bakery, custard, cream and tobacco flavours may benefit from several days or longer. Nicotine shots can slightly alter the flavour, so a short rest is worthwhile if the liquid tastes sharp or muted immediately after mixing.

Store the bottle upright in a cool, dark cupboard with the cap on. Avoid leaving e-liquid on a sunny windowsill, in a hot car or near a radiator. Heat and light can affect flavour quality over time. There is no benefit in repeatedly opening the bottle to let air in; shaking it occasionally is usually enough.

Getting the flavour and strength right

Shortfills offer choice, but they are usually best suited to lower nicotine strengths. A standard 50ml shortfill with one 18mg shot makes approximately 3mg, which works well for many direct-to-lung vapers taking longer, more frequent draws. It may not be satisfying if you currently use 10mg or 20mg nic salts in a low-power pod.

If you need a stronger nicotine level, do the maths before ordering. You may need a specifically designed 40ml-in-60ml shortfill to make 6mg with two 18mg shots, or you may be better served by 10ml nic salts. Chasing a higher strength by forcing extra shots into a bottle can dilute the flavour and leave you with more liquid than the bottle can hold.

Flavour concentration also matters. A shortfill is formulated to account for the addition of the stated nicotine shot. Once mixed as intended, it should taste as the manufacturer planned. Adding more unflavoured liquid than recommended can make the flavour noticeably lighter.

Common shortfill problems and simple fixes

If the flavour seems weak after mixing, shake the bottle again and give it a day or two. A fresh coil also makes a real difference, especially after vaping a strong menthol, dark dessert or heavily sweetened liquid. If the liquid is too thick for your pod, move to a 50/50 e-liquid rather than increasing wattage beyond the coil’s recommended range.

If you get a harsh vape, check that your coil is fully primed and that the nicotine strength suits how you vape. Harshness can come from a dry coil, too much power, a high-PG blend or simply taking a direct-to-lung draw at a nicotine strength better suited to mouth-to-lung vaping.

For adult vapers who use refillable hardware regularly, shortfills are a straightforward way to keep favourite flavours on hand while controlling nicotine strength. Start with a bottle designed for your preferred shot, match the VG/PG ratio to your coil, and give the finished mix a proper shake before filling your tank.