Shortfill e-liquids occupy an important and slightly unusual niche in the Irish vaping market. They exist because of a specific interaction between European health regulations and the practical realities of vaping for users who consume larger quantities of e-liquid, particularly those using sub-ohm devices. Understanding what shortfills are, why they exist, and how to use them correctly unlocks access to a significantly wider range of flavours at substantially better value than buying standard ten millilitre nicotine-containing bottles.
If you have been vaping for a while and currently buy nicotine-containing ten millilitre bottles exclusively, switching to shortfills and nicotine shots may be one of the most immediately impactful changes you can make to both your vaping experience and your monthly spend.
Why Shortfills Exist: The TPD Explanation
The EU Tobacco Products Directive, which governs the sale of vaping products across Europe including Ireland, restricts nicotine-containing e-liquid to bottles no larger than ten millilitres. This restriction was introduced to limit nicotine exposure and as a child safety measure, since larger bottles of nicotine liquid represent a more significant poisoning risk if mishandled. The ten millilitre cap applies specifically to liquid that contains nicotine.
Liquid that contains no nicotine at all is not subject to this restriction. Manufacturers are free to sell zero-nicotine e-liquid in any bottle size. The shortfill format exploits this distinction: a large bottle, typically fifty or one hundred millilitres, is filled with zero-nicotine e-liquid but deliberately underfilled, leaving a space at the top of the bottle. This space is precisely sized to accommodate one or more separate nicotine shots.
The nicotine shot is a small bottle, typically ten millilitres, containing nicotine at a specific concentration but no flavour. When the nicotine shot is added to the shortfill bottle and mixed, the resulting liquid has both flavour and nicotine at a concentration determined by the volumes involved. The regulatory requirement is satisfied because neither the shortfill nor the nicotine shot on their own are the finished nicotine-containing e-liquid that the restriction applies to.
The Maths of Mixing
The standard shortfill format is a fifty millilitre liquid in a sixty millilitre bottle, leaving ten millilitres of space for one nicotine shot. Adding one ten millilitre shot of eighteen milligram nicotine to this setup produces sixty millilitres of finished liquid at three milligrams per millilitre. This is a common concentration for sub-ohm vapers.
If you want a higher concentration, two nicotine shots can be added to a one hundred millilitre shortfill in a one hundred and twenty millilitre bottle, or you can use a higher-concentration nicotine shot. Salt-based nicotine shots are available in higher concentrations and produce a smoother hit at equivalent nicotine levels, making them suitable for vapers who want above three milligrams in their finished liquid without the harshness that freebase nicotine produces at the same concentration.
The formula for calculating finished nicotine concentration is straightforward. Take the nicotine shot volume multiplied by the shot concentration, then divide by the total finished volume. A ten millilitre shot of eighteen milligrams added to fifty millilitres of zero-nicotine liquid gives sixty millilitres total, at ten multiplied by eighteen divided by sixty, which equals three milligrams per millilitre.
How to Mix Correctly
Mixing is a simple physical process. Remove the cap from the shortfill bottle. Open the nicotine shot and pour its contents into the shortfill bottle. Replace the cap on the shortfill bottle and shake vigorously for thirty seconds to one minute. The two components are miscible, meaning they blend readily, and no specialised equipment is needed.
After initial mixing, some vapers allow the mixture to steep for a short period before use, typically fifteen to thirty minutes, to ensure the nicotine is evenly distributed through the liquid and any minor temperature changes from the mixing process have settled. In practice, many vapers use the mixed liquid immediately without any noticeable quality difference.
Nicotine safety during mixing is worth noting. Pure nicotine at the concentrations used in nicotine shots is genuinely harmful if absorbed through the skin in significant quantities. While the risk from a small spill during routine mixing is modest, washing hands after handling nicotine shots is sensible practice. Keep the shots out of reach of children and dispose of empty bottles responsibly.
What Shortfills Offer That Standard Bottles Do Not
The primary advantages of shortfills are range, quality, and cost. On range: the zero-nicotine liquid restriction means that shortfill producers are subject to far fewer regulatory constraints on bottle size, which has encouraged the development of a market with an extraordinary breadth of flavour options. Many premium e-liquid brands, particularly those positioning themselves at the quality end of the market, release their flagship products primarily or exclusively in shortfill format. Finding these brands and flavours is easiest through a specialist retailer with a wide selection, such as a dedicated online vape shop carrying both shortfills and matching nicotine shots, allowing you to browse the full range before committing to a purchase.
On cost: the price per millilitre of finished e-liquid from a shortfill plus nicotine shot is typically forty to sixty percent lower than buying equivalent volume in ten millilitre nicotine-containing bottles. A fifty millilitre shortfill at twelve to fifteen euros plus a nicotine shot at one to two euros gives sixty millilitres of finished liquid at a total cost of thirteen to seventeen euros. Equivalent volume in ten millilitre bottles at three to five euros each would cost eighteen to thirty euros.
Choosing the Right Shortfill for Your Device
Shortfill liquids are generally formulated for sub-ohm devices and carry high vegetable glycerin content, typically seventy to eighty percent VG and twenty to thirty percent PG. This ratio produces the dense vapour and rich flavour delivery that sub-ohm vaping is known for but makes the liquid too viscous to wick efficiently in MTL pod devices with narrow coil channels.
If you use a pod system or MTL device, check the PG/VG ratio of any shortfill you are considering. Some manufacturers produce shortfills in higher-PG formulations specifically for MTL use, but these are less common than the standard high-VG format. Using a high-VG shortfill in an MTL device will cause wicking problems, dry hits, and accelerated coil deterioration.
Also consider the flavour profile in relation to your coil situation. Heavily sweetened shortfill liquids, particularly dessert and candy profiles, will shorten coil life significantly regardless of device type. If you prioritise coil longevity, look for lower-sweetener formulations, which are increasingly labelled as such by quality-conscious brands.
Storage of Mixed and Unmixed Shortfills
Unmixed shortfill bottles containing zero-nicotine liquid have a longer effective shelf life than mixed bottles containing nicotine, because the nicotine oxidation process has not yet begun. Keeping nicotine shots separate until you are ready to use the liquid is therefore the optimal storage strategy when buying in bulk.
Once mixed, the finished liquid should be stored with the same care as any other nicotine-containing e-liquid: cool, dark, away from oxygen exposure. A mixed sixty millilitre bottle used over the course of two to three weeks by a moderate vaper will typically not suffer noticeable degradation within that timeframe when stored correctly.