The label on a disposable says 20 mg/ml, and the label on a bottle of e-liquid says 20 mg/ml, so the obvious assumption is that the two deliver the same thing. They do not. The number describes concentration in the liquid, and the amount of nicotine you actually inhale depends on how much liquid the device turns into vapour, which is a property of the hardware.
Switching from a sealed device to a refillable pod is mostly an exercise in translating concentration into daily intake. Get the arithmetic right and the transition is unremarkable. Get it wrong in either direction and the first week is either flat or unpleasant.
Start from total nicotine, not from the label
Every device and every bottle contains a fixed quantity of nicotine, and that quantity is the only figure that compares directly.
| Format | Concentration | Volume | Total nicotine |
|---|---|---|---|
| Prefilled disposable | 20 mg/ml | 2 ml | 40 mg |
| Prefilled pod | 20 mg/ml | 2 ml | 40 mg |
| 10 ml bottle | 20 mg/ml | 10 ml | 200 mg |
| 10 ml bottle | 10 mg/ml | 10 ml | 100 mg |
| 10 ml bottle | 18 mg/ml | 10 ml | 180 mg |
A 2 ml disposable and a 10 ml bottle at the same strength differ by a factor of five in total nicotine. That is the number that tells you how long a bottle should last, and the number that tells you whether a switch in concentration is up or down.
Work out your current daily intake
Take the number of devices you finish in a week. A device contains 40 mg, so three devices a week is 120 mg, or about 17 mg a day. Two devices a week is about 11 mg a day. Someone who finishes a device every ten days is at roughly 6 mg a day.
This is an estimate, not a measurement: it assumes you use the device to the end, and it ignores the liquid left in a device you stop using early. But it is accurate enough to choose a starting strength, which is all that is needed. The absorption guide explains why the nicotine delivered per puff is lower than the nicotine contained per puff.
Choosing the bottle strength
The common mistake is to buy a bottle at 20 mg/ml because the disposable was 20 mg/ml, then use the pod at higher power and find it far too strong. The reverse mistake is to drop to 6 mg/ml to be cautious and vape constantly for a week.
Two factors shift the effective delivery in a pod system relative to a disposable. A pod usually runs at higher power, which vaporises more liquid per puff, and a refillable device is often used at a looser airflow, which increases the volume inhaled. Both push intake up at the same concentration.
A reasonable starting point for someone on 20 mg/ml disposables is 18 to 20 mg/ml in a pod at similar power, or 12 to 15 mg/ml if the pod runs noticeably hotter. Someone on one device a week is a light user and will usually be comfortable lower. The pod versus disposable strength comparison sets out the ranges by device type.
Salts or freebase changes the feel, not only the number
Most disposables use nicotine salts, which are smoother at high concentration. A bottle at 20 mg/ml in freebase form will feel considerably harsher than the disposable it replaces, even though the number on the label matches. That difference is pH and throat impact rather than dose — throat hit has its own set of causes — and it is why a direct swap often disappoints.
If the goal is a like-for-like replacement, choose a salt at the same concentration. If the goal is to step down, freebase at a lower concentration is the more natural route, because the harsher throat hit makes constant use less appealing. The freebase and salts comparison covers the absorption difference, which is smaller than the difference in feel.
What a bottle should last
At 17 mg a day, a 10 ml bottle at 20 mg/ml contains just under twelve days of nicotine. In practice a bottle lasts less, because a pod system wastes liquid: priming a new coil, the liquid left in a pod when you change flavour, and the small loss at every refill. Expect eight to ten days.
If a bottle is gone in three days, either your intake has risen or the pod is leaking. The first is a strength question and the second is a hardware question, and the two look identical on the calendar. Our guide to leaks is the place to start on the second.
The first week is not representative
Switching devices changes the ritual as well as the dose: a pod requires refilling, priming and charging, and people often vape more in the first days simply because the device is new. Judge the strength after a week, not after a day.
Two signals say the strength is too high: a headache or nausea in the evening after a normal day of use, and a reluctance to vape at all despite wanting to. Two signals say it is too low: finishing a pod far faster than the arithmetic predicts, and a persistent sense of not having had a cigarette-equivalent. The overshoot symptoms guide covers the first pair.
Stepping down afterwards
Once the pod is established, reducing concentration is easier than it was on a disposable, because the bottle comes in increments. A drop of 3 to 5 mg/ml every few weeks is tolerable for most people; a drop of 10 mg/ml in one step is not, and it usually produces a temporary increase in how often you vape. Our guide to stepping down nicotine covers the pace and the plateaus.
If the aim is eventually to stop nicotine rather than to switch devices, the nicotine strength guide sets out the full ladder from 20 mg/ml to zero.
Frequently asked questions
Is a 20 mg/ml bottle stronger than a 20 mg/ml disposable?
The concentration is identical; the total nicotine is five times higher because the volume is five times larger. Whether a puff delivers more depends on the power and airflow of the device it goes into.
Can I use a 20 mg/ml bottle in a sub-ohm tank?
Not comfortably. High-power devices vaporise far more liquid per puff, and 20 mg/ml at that output is harsh to the point of being unusable. High-strength liquid belongs in low-power, tight-draw pods.
Why does the bottle taste weaker than the disposable?
Because flavour concentration and nicotine concentration are separate specifications, and a disposable is formulated for one specific coil. A bottle in a different pod will taste different at the same nicotine level.
How many millilitres a day is normal?
For a former disposable user in a pod, 1 to 2 ml a day is typical. Above 3 ml a day at 20 mg/ml is a high intake and worth checking against the arithmetic.
Do I need to change the coil when I change strength?
Not for strength alone. Change it when the taste turns, or when the liquid changes substantially in viscosity, which usually means a different VG ratio.
