Shortfill nicotine maths: every 50ml and 100ml combination

Nicotine strength is measured in milligrams per millilitre. A 10ml shot at 18mg holds 180mg of nicotine in total. When you pour it into a shortfill, that 180mg spreads out across the whole bottle.

So the formula is: (shot strength x shot ml) / total ml. For 50ml plus one shot: 180 / 60 = 3mg. For 100ml plus one shot: 180 / 110 = 1.64mg. That is the whole trick. The rest is arithmetic, which we have done for you below.

Nicotine is addictive, so it pays to know exactly what you are mixing rather than guessing.

Most 50ml shortfills come in a 60ml bottle, so there is only room for one shot without decanting. Two or three shots means pouring into a larger empty bottle first. Some people do that to reach a stronger mix for a mouth-to-lung tank.

With 18mg shots, a 50ml bottle gives 3mg with one shot, about 5.1mg with two and 6.75mg with three. With 20mg shots the figures are 3.3mg, 5.7mg and 7.5mg. Flavour gets noticeably weaker by the third shot because 30ml of unflavoured liquid is going into 50ml of flavour.

Empty bottles live in e-liquid bottles if you need more room. Label the new bottle straight away.

A 100ml shortfill usually arrives in a 120ml bottle with room for two shots. That is the standard way to land at 3mg, the most common sub-ohm strength.

One shot gives a mild 1.64mg, ideal if you are deliberately stepping down. Three shots needs a bigger bottle and gives about 4.15mg with 18mg shots, or 4.6mg with 20mg shots. Getting a 100ml up to 6mg takes five 18mg shots, at which point flavour suffers badly and you would be better off with a stronger shot or a different product.

Shots for this live in nicotine shots.

Here is every common combination in one place, for both 18mg and 20mg shots. All figures are rounded to two decimal places, which is far more precise than any tongue can tell.

The pattern is worth remembering: a 20mg shot always lands about 10% stronger than an 18mg one in the same mix. If you want a 50ml at a little over 3mg, a single 20mg shot does it. If you are trying to keep 100ml mild, one 18mg shot is the gentlest way in. Shot strength is printed on every bottle, so check before you pour rather than after.

Odd-sized bottle, a 15mg shot, or a 60ml shortfill from a niche brand? Plug the numbers in below. The calculator uses the same formula as the chart, so it works for any bottle size and any shot strength you come across.

If the result is lower than you wanted, you have three options: add another shot, use a higher strength shot, or accept a slightly milder mix. Shots like the Nic Nic 100VG come in 15mg and 18mg, so check the label before you mix. A 15mg shot in 50ml gives 2.5mg, not 3mg, which is a small difference you might still notice.

Every shot is unflavoured, so it dilutes the shortfill. One shot in 50ml means one sixth of the final bottle is plain nicotine base. Shortfill makers allow for this, which is why a 50ml with one shot tastes as intended.

Push to two or three shots and the flavour share drops to around 71% and 63%. Some vapers like that softer taste, many find it bland. If you need a stronger mix, a 10ml freebase or nic salt bottle at the strength you want will taste better than an overloaded shortfill.