VG (vegetable glycerin) and PG (propylene glycol) are the two base liquids that make up the bulk of every vape juice. Together they typically account for 90% or more of the bottle, with nicotine and flavorings making up the rest. The ratio between VG and PG determines how thick the vapor is, how strong the throat hit feels, and how well the flavors come through.
What VG Does
Vegetable glycerin is a thick, slightly sweet liquid derived from plant oils. Its chemical structure makes it exceptionally viscous, roughly 50 times thicker than water at room temperature. That thickness is what produces dense vapor clouds when heated. Mixes with 70% VG or higher create noticeably thicker, larger clouds compared to juice with more PG.
VG also gives the inhale a smoother, softer feel. If you’ve ever tried a high-VG juice and noticed the throat hit was almost nonexistent, that’s by design. The tradeoff is that VG doesn’t carry flavor as effectively as PG, so very high-VG liquids can taste slightly muted.
What PG Does
Propylene glycol is thinner and nearly tasteless. Its main job in vape juice is twofold: it dissolves and carries flavorings more effectively than VG, and it delivers the “throat hit,” that sharp sensation at the back of the throat that mimics the feel of smoking a cigarette. In a published comparison of different PG/VG ratios, participants consistently rated the highest PG concentration (70% PG) as producing a noticeably stronger throat hit than other blends. Higher PG concentrations also appear to increase nicotine delivery, which may contribute to that sensation.
PG is widely used as a solvent and flavor carrier in food, cosmetics, and pharmaceuticals because it dissolves a broader range of compounds than glycerin and doesn’t evaporate quickly. That low volatility keeps flavors consistent from the first puff to the last.
Common VG/PG Ratios
When you see something like “70/30” on a bottle, the first number is VG and the second is PG. Here’s how the most popular ratios compare:
- 50/50: Light vapor, medium throat hit, strong flavor. The go-to starting point, especially for people switching from cigarettes or disposables.
- 60/40: A middle ground. Slightly more vapor, still decent flavor and throat hit. Works in most devices.
- 70/30: Thick clouds, mild throat hit, good flavor. The standard ratio for shortfill bottles and sub-ohm vaping.
- 80/20: Very thick clouds, barely any throat hit, slightly muted flavor. Built for cloud-chasing setups and drippers.
If you’re unsure, 50/50 is the safest bet. It matches the feel of a disposable vape, pairs well with beginner kits, and plenty of vapers never feel the need to change from it.
Which Ratio Works With Your Device
The ratio you pick needs to match your hardware. Thicker juice won’t wick properly in a device designed for thin liquid, and thin juice can flood a tank built for thick liquid.
Pod kits and other low-power, mouth-to-lung devices work best with 50/50 e-liquid. These systems have small wicking holes and low wattage, so they need thinner juice to keep up. Some newer pod systems can handle slightly higher VG with specialized low-resistance coils, but they aren’t optimized for it.
Sub-ohm kits, which run at 40 watts or higher and use coils below 1.0 ohm (often 0.4 ohm or lower), are designed for thick, high-VG juice in the 70/30 to 80/20 range. These devices push more power through larger coils, vaporizing thicker liquid efficiently and producing the big clouds that high-VG ratios are known for. Putting thin 50/50 juice in a sub-ohm tank often leads to leaking and an unpleasantly harsh hit.
How VG/PG Ratio Affects Coil Life
High-VG juice is harder on your coils in a specific way: because it’s so thick, it wicks more slowly into the cotton. If you take several puffs in quick succession without giving the wick time to resaturate, you get a dry hit, which burns the cotton and can ruin the coil. Taking a few “primer puffs” (pulling on the device without firing it) helps draw juice into the wick and reduces this problem.
The black, gunky buildup that shortens coil life is mostly caused by sweeteners in the flavorings, not by VG itself. Very sweet e-liquids will caramelize on the coil over time regardless of the VG/PG ratio. If your coils are dying quickly, switching to a less heavily sweetened flavor usually helps more than changing the ratio.
Safety and Sensitivity
Both VG and PG are classified as “Generally Recognized as Safe” (GRAS) by the FDA for ingestion in food and medicine. That designation, however, applies to eating and drinking them. Their effects on the respiratory system when inhaled as vapor are far less studied, and that GRAS label does not extend to inhalation.
A small percentage of people are sensitive to propylene glycol. Contact allergy to PG shows up in roughly 3.5% of people tested for suspected contact dermatitis, causing skin irritation, redness, or hives where the substance touches skin. In vaping, PG sensitivity can show up as a persistent sore or scratchy throat, dry mouth, or mild skin reactions around the lips. If you notice these symptoms and they don’t go away after staying hydrated, switching to a higher-VG ratio (like 70/30 or 80/20) reduces PG exposure significantly and often resolves the issue.
VG sensitivities are much rarer. The most common complaint with very high-VG juice is mild dehydration or dry mouth, which happens because glycerin absorbs moisture. Drinking more water on days you vape heavily usually takes care of it.