100ml shortfill, the strength its bottle really allows

A 100ml shortfill never leaves the shop with nicotine in it. The bottle arrives at 0 mg with a gap at the top, and adding the nicotine is up to the buyer. That gap is not an accident. It decides in advance the strength you can reach, and that strength also depends on the shots you choose. Before ordering a large bottle, it pays to know what the bottle allows and what it rules out.

100ml shortfill strength, the short answer

A 100ml shortfill becomes a nicotine e-liquid once you add 10 ml nic shots to a bottle designed to take them. UK rules under the Tobacco and Related Products Regulations 2016 cap any nicotine-containing e-liquid at 10 ml per bottle and 20 mg/ml, which is why the large format is sold nicotine free.

The usual bottle holds 100 ml of liquid in a 120 ml container. It therefore takes two shots at most, for a final strength of around 3 mg/ml. Aiming higher means working outside the original bottle.

What the empty space decides for you

The UK retailer listings consulted describe 100ml shortfills as 100 ml of liquid in a 120 ml bottle. Those 20 ml of headroom match exactly two 10 ml shots. The maker has, in effect, chosen the highest strength you can reach without decanting.

The real strength with one or two shots

The sum is a single division, total nicotine over total volume. The result depends on the strength of your shots, and in the UK 18 mg/ml shots sit on the shelves alongside 20 mg/ml ones.

Shots added	Final volume	With 18 mg/ml shots	With 20 mg/ml shots
1	110 ml	1.6 mg/ml	1.8 mg/ml
2	120 ml	3.0 mg/ml	3.3 mg/ml

18 or 20 mg/ml shots, a gap to plan for

Both strengths sit side by side on UK shelves, and the difference carries through to the bottle. With two shots the mix reaches 3.0 mg/ml on one side and 3.3 mg/ml on the other, about 10 per cent more nicotine with 20 mg/ml shots. Switching shot brands between two mixes is enough to change the strength, and nothing on the shortfill label will show it.

Going beyond 3 mg/ml with a large bottle

The 120 ml bottle caps the strength at around 3 mg/ml. For anyone after a stronger mix from the same recipe, extra shots beyond the planned space are needed, which means a second empty bottle and two trade-offs.

Splitting the liquid between two bottles

The simplest route is to pour half the liquid, 50 ml, into an empty bottle of at least 70 ml. Each half then becomes a separate mix with its own strength. The table below sets out the possible combinations with 18 mg/ml shots.

How the 100 ml is split	Shots used	Result
Original bottle, no split	2	120 ml at 3.0 mg/ml
50 ml and 50 ml, one shot in each	2	two 60 ml bottles at 3.0 mg/ml
50 ml and 50 ml, two shots in each	4	two 70 ml bottles at 5.1 mg/ml
50 ml with one shot, 50 ml with two	3	60 ml at 3.0 mg/ml and 70 ml at 5.1 mg/ml
50 ml with no shot, 50 ml with two	2	50 ml at 0 mg and 70 ml at 5.1 mg/ml

The sum is the same on every row. Two 18 mg/ml shots bring 360 mg of nicotine, spread through 70 ml, or 5.1 mg/ml; with 20 mg/ml shots the same half reaches 5.7 mg/ml. The last two rows let you prepare two strengths from one recipe. For every other case, our guide to how many nicotine shots you need sets out the formula and its tables.

The flavour gets diluted

Each shot adds 10 ml with no flavouring. In the original bottle, the 100 ml of recipe make up 83 per cent of the finished 120 ml. In a half topped up with two shots, the 50 ml of recipe make up only 71 per cent of 70 ml, a recipe around 14 per cent weaker in flavour than the original bottle with two shots.

The taste may therefore come across as more muted. A large bottle pushed past two shots will not quite deliver the profile its maker intended.

The PG/VG ratio moves too

Shots carry their own ratio. A 30/70 (PG/VG) shortfill topped up with two 50/50 shots moves to about 33/67, and to 36/64 in a half topped up with two shots. UK shelves also carry 70VG shots, which leave a 30/70 shortfill at 30/70. Our guide to the PG/VG ratio after nicotine shots shows how to work it out.

When a large bottle is the wrong choice

With a ceiling of around 3 mg/ml in its original bottle, the 100ml shortfill mainly suits low strengths and kit that produces plenty of vapour, such as direct lung devices.

For a higher strength or a mouth to lung pod, a ready made 10 ml nicotine e-liquid is a better fit than piling up shots. Our nicotine strength guide helps you take stock before ordering.

The right steps before adding shots

First, check the total capacity of the bottle, shown on the listing or under the label. Listings usually state a 120 ml bottle, but a large bottle sold at another volume leaves a different gap, and so a different final strength. Then count your shots and read their strength before opening anything, since an 18 mg/ml shot does not give the same result as a 20 mg/ml one.

Once the shots are in, the bottle no longer carries accurate information. Its label still says 0 mg although it now contains nicotine. Write the strength and the date of the mix on the bottle, especially if you prepare several strengths.

Shake the bottle until the liquid is even. Close every opened shot with its safety cap, and keep bottles and shots stored safely, out of reach of anyone under 18, because the result is a 100ml shortfill turned into a nicotine e-liquid like any other.

FAQ

These five questions come up often when topping up a large bottle, alongside everything covered above.

Does a nic salt shot give the same strength?

Yes. Strength depends only on the amount of nicotine added, and a 20 mg/ml salt shot adds as much as a freebase shot at the same strength. Only the throat sensation differs, as our comparison of nic salt and freebase nicotine explains.

Why are nic shots always sold in 10 ml bottles?

Because UK rules cap any bottle of nicotine-containing e-liquid at 10 ml. A 20 ml or 50 ml shot cannot be sold legally in the UK.

Can I use just one shot in a 100ml bottle?

Yes. A single 18 mg/ml shot gives 110 ml at 1.6 mg/ml. The bottle then keeps 10 ml of headroom, which makes shaking the mix easier.

Can I add a shot to an e-liquid that already contains nicotine?

You can, but the sum changes. A 10 ml bottle at 6 mg/ml holds 60 mg of nicotine. With an 18 mg/ml shot you get 240 mg in 20 ml, or 12 mg/ml, and the flavour is halved.

Can a 100ml bottle be topped up with a nicotine base instead of shots?

Yes, provided it fits in the headroom. A nicotine base is also sold in bottles of 10 ml at most, sometimes at a strength below the shots, which gives a weaker final mix than shots would.

100ml shortfill, choosing a strength before opening the bottle

The 120 ml bottle sets the rules. Two shots give around 3 mg/ml, and anything beyond that goes through a second bottle, with diluted flavour and a shifting ratio.

Preparing a 100ml shortfill with nicotine therefore means choosing your strength before opening the bottle, then writing the result on the label. The same reasoning applies to every shortfill size.

Editorial content for adult readers only. Vaping products can contain nicotine, a substance that causes addiction. Nicotine vaping products are not for sale to anyone under 18 in the UK. This article is not a buying recommendation.