Ask a new vaper what the most confusing aspect of choosing e-liquid is, and the PG/VG ratio will frequently top the list. The numbers appear on every bottle, the abbreviations are used without explanation across most vaping retail content, and the practical consequences of choosing the wrong ratio for your device can range from mildly disappointing to seriously problematic. Yet the underlying concepts are straightforward once explained clearly, and understanding them gives you meaningful control over your vaping experience.
This guide explains what propylene glycol and vegetable glycerin actually are, what each contributes to the vaping experience, how different ratios change what you taste and feel, and which ratios work with which device types.
What Propylene Glycol Is
Propylene glycol is a synthetic organic compound classified as a generally recognised as safe food additive and widely used across pharmaceuticals, food manufacturing, and cosmetics. It is a thin, almost water-like liquid with a faint sweet taste. In e-liquid, PG serves several distinct functions simultaneously.
As a carrier, PG is excellent at suspending and distributing flavour compounds evenly through the finished liquid. This is why high-PG liquids are often associated with flavour clarity and accuracy: the PG carries the flavour compounds efficiently and releases them readily when heated. The thin viscosity of PG also allows it to wick through fine cotton channels quickly, making it well-suited to MTL coils and pod systems where the narrow wicking paths benefit from lower-viscosity liquid.
The throat hit associated with vaping comes primarily from PG. At the concentrations used in e-liquid, PG vapour creates a mild irritant effect at the back of the throat that many former smokers find familiar and satisfying. Higher-PG liquids produce a more pronounced throat hit, while high-VG liquids are notably smoother.
What Vegetable Glycerin Is
Vegetable glycerin is a natural compound derived from plant oils, typically soybean, coconut, or palm. It is a thick, viscous liquid with a mild sweetness. Unlike PG, VG is the primary contributor to vapour volume: its molecular structure produces dense, visible clouds when heated, and the higher the VG percentage, the larger and denser the vapour production.
VG also contributes to the smoothness of the vaping experience. High-VG liquids are noticeably softer on the throat than high-PG equivalents at similar nicotine concentrations. This smoothness makes VG-dominant liquids more comfortable at higher wattages and during extended sessions. The sweetness of VG adds a background note that is usually desirable in fruit and dessert liquids but can occasionally conflict with profiles trying to achieve a drier tobacco character.
The main limitation of VG is its viscosity. At the concentrations used in sub-ohm liquids, typically seventy percent and above, VG is too thick to wick efficiently through the narrow cotton channels of MTL coils. Trying to use a high-VG liquid in a pod device or MTL setup results in inadequate wicking, dry hits, and accelerated coil degradation.
How the Ratio Changes What You Experience
The effects of varying the PG/VG ratio are consistent and predictable. As PG percentage increases: throat hit becomes more pronounced, flavour tends to be cleaner and more accurate to the description, vapour production decreases, and the liquid becomes thinner and easier to wick in tight coils. As VG percentage increases: throat hit softens, vapour production increases significantly, the liquid becomes sweeter and slightly creamier, and the viscosity increases to the point where narrow coils cannot wick it effectively.
Common ratios and their typical applications: fifty-fifty splits work across the widest range of devices and represent the most versatile choice for vapers who use both pod systems and more powerful devices. Seventy VG to thirty PG is the standard formulation for sub-ohm devices seeking good vapour production and smooth delivery. Eighty VG or above is used in high-performance sub-ohm setups where cloud production is a priority. High-PG ratios, sixty-five PG or above, are specifically formulated for MTL and pod devices where wicking speed and throat hit are more important than vapour volume.
Which Ratio Does Your Device Need?
Device compatibility is the most important practical application of understanding PG/VG ratios. The coil resistance and wicking design of your device determine which ratios it can handle effectively. Using the wrong ratio causes predictable and identifiable problems.
If you are using a pod system or MTL pen-style device, look for fifty-fifty or high-PG formulations. The narrow wicking channels in these coils cannot move thick, high-VG liquid efficiently enough to keep the cotton saturated during use. The result is dry hits that taste burnt, premature coil failure, and a genuinely unpleasant experience that is often blamed on the device or the liquid flavour when the real cause is the ratio mismatch.
If you are using a sub-ohm device at twenty watts or above with a low-resistance mesh coil, high-VG liquids are not only appropriate but preferred. The large wicking ports in sub-ohm coil heads are specifically designed for the thicker VG-dominant liquid, and the performance of these devices with fifty-fifty liquid is often underwhelming because the lower VG content cannot produce the vapour density that the coil and airflow design are engineered to deliver.
Mixing Your Own Ratio
Some vapers mix high-VG shortfill bases with higher-PG nicotine shots to achieve a custom ratio. Since nicotine shots are typically in a fifty-fifty or full PG base, adding a ten millilitre nicotine shot to a fifty millilitre seventy VG shortfill base produces a finished sixty millilitre liquid at a ratio of approximately sixty-two VG to thirty-eight PG. This ratio is more versatile than the pure seventy VG starting point and works well in a wider range of devices.
For vapers who want precise ratio control, base liquids in pure PG and pure VG are available for mixing, allowing any target ratio to be achieved by combining the correct volumes. This level of customisation is primarily relevant to users who have established very specific preferences about their experience and want to optimise for them. For most vapers, choosing a pre-mixed ratio appropriate for their device is entirely sufficient.