Shortfills are the UK vape industry response to a regulation that capped nicotine bottle size. Once you understand the law, the format makes complete sense.

The word “shortfill” describes the bottle: the flavoured base is “short-filled” (deliberately under-filled) leaving 20ml of empty space in a 120ml container. That headspace is exactly the right size to take two standard 10ml nicotine shots which the user adds at home. After mixing, the bottle holds 120ml of complete e-liquid at 3mg/ml. Before mixing, the bottle holds 100ml of nicotine-free flavoured base which is legally distinct from a nicotine product under UK regulation.

The format exists entirely because of TRPR Regulation 36 which limits nicotine-containing e-liquid to 10ml per individual container. This rule was introduced in 2016 as part of the EU Tobacco Products Directive (TPD) implementation in UK law plus retained after Brexit through the UK-specific TRPR. The rule was designed to limit accidental nicotine exposure but had the side-effect of making large bottles of pre-mixed nicotine e-liquid illegal. Manufacturers responded by separating the flavour base from the nicotine. The base is sold large plus nicotine-free. The nicotine is sold separately in compliant 10ml shots. Both are sold together as a “shortfill plus nic shot” combination at the till.

Before TRPR took effect in May 2017, UK vapers could buy 30ml, 60ml or even 120ml bottles of pre-mixed nicotine e-liquid directly. These large pre-mixed bottles disappeared overnight when the law took effect. Industry needed roughly 6-9 months to refine the shortfill format into the form vapers see today. The 100ml shortfill became the dominant size because it matched the typical monthly consumption of UK sub-ohm vapers plus delivered the maximum cost saving over 10ml bottles while staying within practical container sizes.

The four ingredients of a complete shortfill

A complete mixed shortfill contains four core ingredients. Vegetable glycerine (VG) typically makes up 70-80 percent of the volume. It is the thick component that produces dense vapour clouds when heated by the coil. Propylene glycol (PG) typically makes up 20-30 percent. It is thinner than VG plus carries the flavour molecules to your tongue. Food-grade flavour concentrates typically make up 5-10 percent. These provide the actual taste of the e-liquid. Nicotine typically makes up 3 percent (3mg/ml strength). It is added at home via the nic shots.

The first three ingredients (VG, PG plus flavour) are premixed at the factory in the nicotine-free base. They produce a complete-tasting flavoured liquid that you could vape standalone if you do not want nicotine (some people do this and call it “0mg vaping”). The fourth ingredient (nicotine) is added at home via the standardised 10ml shots. The shots are typically 18mg/ml freebase nicotine in a matching VG/PG ratio so they integrate seamlessly with the base when shaken. The result is identical to factory-mixed e-liquid in every way except the production location of the final mix.

• Bottle is short-filled. 120ml bottle holding 100ml of base plus 20ml of headspace.
• Base is nicotine-free. Sold legally outside TRPR Regulation 36’s 10ml cap.
• Nicotine sold separately. Two 10ml shots in compliant containers.
• User mixes at home. Pour shots, shake, rest plus vape.
• Final strength 3mg/ml. Standard sub-ohm strength after mixing.

For more context on shortfills including how to mix them, how to choose the strength plus device pairing advice, head to our complete Shortfill consumer guide hub where every practical question has its own article.