PG VG ratios are the amount of propylene glycol (PG) and vegetable glycerin (VG) in an e-liquid. These ingredients affect how an e-liquid behaves. High PG e-liquids tend to have more focus on flavour, but can have a harder throat hit. High VG liquids produce more vapour and are smoother, but they can give less distinct flavour and are harder on coils. Both types of e-liquids are great, it’s all about using them in the right device.