Max VG Isn't a Number You Choose — It's a Number Your Ingredients Leave You

You want a smooth 70/30 VG/PG juice for big clouds, so you set that as your target, mix your batch — and your finished liquid comes out closer to 60/40. Nothing leaked and nothing evaporated. The problem is that “max VG” is not a dial you turn. It’s a ceiling that your nicotine base and your flavour concentrates set for you before you add a single drop of pure vegetable glycerine. Understanding why turns a frustrating guessing game into one line of arithmetic.

Two ingredients smuggle PG into your mix

A DIY e-liquid is built from four things: nicotine base, flavour concentrate, pure PG (propylene glycol), and pure VG (vegetable glycerine). You get to choose how much pure PG and pure VG go in — but the nicotine base and the flavour aren’t pure. Each one is itself dissolved in a carrier, and that carrier is almost always PG.

A typical 100 mg/mL nicotine base is suspended in 100% PG. Most flavour concentrates are PG-based too. So the moment you add nic and flavour, you’ve already committed some fraction of your bottle to PG whether you wanted to or not. That “forced PG” is the whole story. Everything else is just working out how big it is.

The arithmetic: how much of the batch each ingredient claims

Start with nicotine. The fraction of your bottle taken up by the nic base is simply your target strength divided by the base strength:

nic fraction = target nic (mg/mL) ÷ base nic (mg/mL)

Mixing a 3 mg/mL juice from a 100 mg/mL base means nicotine is 3 ÷ 100 = 3% of the batch. If that base is 100% PG, then 3% of your entire bottle is now locked to PG. Halve the base to 50 mg/mL and the nic jumps to 6% of the batch — the weaker your base, the more of the bottle it eats, and the more PG (or VG) it drags along.

Flavour works the same way. If you dose 10% flavour and that flavour is 100% PG, that’s another 10% of the batch forced to PG. Add the two together:

forced PG = (nic fraction × base PG%) + (flavour % × flavour PG%)

And the ceiling falls straight out:

max VG = 100% − forced PG

With a 3 mg/mL target from a 100 mg/mL PG base and 10% PG-based flavour, forced PG = 3% + 10% = 13%, so your maximum achievable VG is 87%. Ask for 90% VG and it’s simply impossible with these ingredients — not because you mixed wrong, but because 13% of the bottle can never be VG. That’s exactly what the PG/VG Ratio Calculator reports: the max VG you can reach, the minimum PG locked in, and a per-ingredient breakdown of where every percent goes.

Why the calculator refuses some recipes outright

There’s a hard limit hiding in the same math. Your nic fraction plus your flavour percentage can’t exceed 100% of the batch — there’d be no room left for the carriers. Try to mix 30 mg/mL from a 50 mg/mL base (60% of the batch) with 45% flavour and you’re already at 105%. The tool flags this as infeasible rather than handing you a nonsense ratio, because the recipe physically can’t be poured. If you hit that wall, you need a stronger nic base, less nicotine, or less flavour.

How to actually raise your VG ceiling

Once you see forced PG as the enemy of high VG, the levers are obvious:

• Use a VG-based (or 50/50) nicotine base. This is the single biggest lever. If your base is 100% VG instead of 100% PG, the nicotine contributes zero forced PG — it adds VG instead. A max-VG mixer should never buy a PG nic base.
• Use the strongest nic base you can dose accurately. A 100 mg/mL base takes up half the bottle-space of a 50 mg/mL base for the same target strength, so it smuggles in half the carrier.
• Lower your target nicotine. Dropping from 6 mg/mL to 3 mg/mL halves the nic fraction and everything it carries.
• Cut the flavour percentage. Flavour is usually the largest single source of forced PG. Going from 15% to 8% flavour frees up seven whole points for VG. Many concentrates are fine at lower doses if you steep them longer.
• Hunt for VG-soluble flavours. A minority of concentrates come VG-based; swapping even a couple in shaves the forced-PG total.

Stack a VG nic base with a modest flavour percentage and “max VG” quietly climbs into the 90s without any wishful thinking.

Why the PG/VG ratio matters at all

None of this is pedantry — the ratio changes how the juice performs. Higher VG is thicker and gummier, produces bigger, denser clouds, mutes flavour slightly, and needs a low-resistance, high-airflow atomiser to wick properly. Higher PG is thinner, carries flavour more sharply, gives a stronger throat hit, and wicks easily in tight coils and pod systems. Chase 90% VG in a pod meant for 50/50 juice and you’ll get dry hits and a burnt coil; run thin 50/50 in a big sub-ohm tank and it’ll leak. The “right” ratio is the one your hardware wants, and knowing your true achievable VG keeps you from ordering a bottle your device can’t handle.

A note on nicotine safety

DIY e-liquid involves handling concentrated nicotine, which is toxic on skin contact and dangerous around children and pets. Always wear gloves, mix in a ventilated space, label every bottle with its strength, and store bases well out of reach. This article and the calculator are for hobbyist mixing information only and are not medical or safety advice — follow the safety guidance from your base supplier.

Once you’ve settled on a ratio and target strength, run the numbers before you buy: drop your base strength, base PG, target nicotine and flavour details into the PG/VG Ratio Calculator and it will tell you the highest VG you can actually reach — so you order the right base the first time instead of discovering the ceiling after your juice is already mixed.