Anyone who has spent time browsing e-liquids online has almost certainly encountered the term shortfill and perhaps felt momentarily confused. What does it mean? Why do the bottles not come filled to the top? And why do they not contain any nicotine? These are entirely reasonable questions, and the answers reveal a clever and cost-effective approach to buying e-liquid that has become extremely popular in the Irish and broader European market.
What Is a Shortfill?
A shortfill is a bottle of nicotine-free e-liquid that has been intentionally under-filled, leaving space at the top — typically twenty percent of the total bottle capacity — for the addition of a nicotine shot. The most common configuration is a sixty-millilitre bottle containing fifty millilitres of nicotine-free e-liquid, leaving ten millilitres of space.
The reason for this configuration comes down to EU regulation. Under the Tobacco Products Directive, e-liquids containing nicotine can only be sold in containers of up to ten millilitres. Larger volumes are only permitted for nicotine-free e-liquids. Shortfills get around this by selling large quantities of base e-liquid without nicotine, with nicotine shots sold separately in compliant ten-millilitre containers.
What Is a Nicotine Shot?
A nicotine shot — often called a nic shot — is a ten-millilitre bottle of near-pure nicotine diluted in a standard PG/VG carrier. They contain no flavour and are designed solely to add nicotine content to a larger, nicotine-free e-liquid. Nic shots typically come in either eighteen milligrams per millilitre or twenty milligrams per millilitre of nicotine concentration.
The most common nic shot is an eighteen-milligram formulation in a fifty-fifty PG/VG ratio. When added to a fifty-millilitre nicotine-free base in a sixty-millilitre bottle, the resulting blend produces an e-liquid with approximately three milligrams per millilitre of nicotine — a popular strength for sub-ohm vaping.
How to Calculate Your Target Nicotine Strength
The calculation is simpler than it might first appear. The formula is: (nicotine shot strength × nic shot volume) ÷ total volume = final nicotine concentration.
Using the most common shortfill setup: an eighteen-milligram nic shot added to a fifty-millilitre base in a sixty-millilitre bottle gives you (18 × 10) ÷ 60 = three milligrams per millilitre. If you want a higher final strength, you can use a twenty-milligram nic shot instead: (20 × 10) ÷ 60 = approximately 3.3 milligrams per millilitre.
For shortfills that use a different configuration — such as a hundred-millilitre bottle with eighty millilitres of base — two nic shots would be added to fill the space. The same formula applies: add the nicotine content of both shots (18 × 10 + 18 × 10 = 360 milligrams) and divide by the total volume (100 millilitres) to get 3.6 milligrams per millilitre.
Mixing Your Shortfill: Step by Step
The process is very simple and takes less than a minute. First, open your nic shot bottle and remove the nozzle cap from your shortfill. Pour the entire contents of the nic shot bottle into the shortfill bottle. The shortfill bottle should now be filled close to the top. Replace the cap firmly on the shortfill bottle.
Now shake the bottle vigorously for at least thirty seconds to ensure the nicotine is thoroughly and evenly distributed throughout the base e-liquid. Some vapers leave the mixed bottle to steep for a few minutes before use, though with most modern shortfill bases this is not strictly necessary. The result is a ready-to-use e-liquid at your calculated nicotine strength.
PG/VG Ratios and How Nic Shots Affect Them
One consideration that is easy to overlook is the effect that the nic shot has on the PG/VG ratio of the final blend. Most shortfill bases are high-VG formulations, often seventy or eighty percent vegetable glycerine. A standard fifty-fifty nic shot added to a high-VG base will dilute the VG slightly, moving the ratio modestly toward a more balanced blend.
If you are very particular about your PG/VG ratio, you can choose a nic shot with a higher VG content — several manufacturers offer high-VG nic shots specifically for this purpose. For most vapers, the small shift in ratio resulting from a standard nic shot is not perceptible in everyday use.
Cost Advantages
Shortfills are significantly more cost-effective than buying multiple ten-millilitre bottles of nicotine-containing e-liquid. A fifty-millilitre shortfill might cost around ten to fourteen euros, with a nic shot adding one to two euros, giving you sixty millilitres of finished e-liquid for around twelve to sixteen euros. The equivalent volume in individual ten-millilitre bottles would typically cost considerably more.
For regular vapers who consume e-liquid in meaningful quantities, the savings over the course of a month are substantial. The shortfill format has essentially made it financially viable to buy quality e-liquid in bulk without running into regulatory size limits.
Flavour Steeping After Mixing
Some vapers practice steeping — allowing a mixed e-liquid to rest for a period of time before vaping, in the same way that wine or whiskey develops with age. Steeping can smooth out any harshness from the nicotine shot and allow the flavour molecules in the base to settle and integrate. For complex dessert or tobacco flavours, steeping for twenty-four to seventy-two hours can produce a noticeably better result.
Simpler fruit and menthol flavours tend to benefit less from steeping and are generally ready to vape immediately after mixing. Whether you steep or vape immediately is a matter of personal preference and patience — there is no right answer, only experimentation.