Peated whiskies have a PPM (parts per million) level, which determines the phenol content of the malted barley after kilning. Phenols are a group of compounds released from burning peat, which denote smoky and peaty character, more of which are imbued the longer the barley is smoked. Therefore, a higher PPM will influence the taste of a whisky.

The average amount of PPM for a peated whisky is around 20-30 ppm. However, there are more heavily peated whiskies that reach a higher PPM. For example, Ardbeg usually has a level of 50-55 ppm, making them firmly peated but not overwhelming - so that the flavours of the base spirit and casks still shines through. The whisky with the highest PPM is The Octomore, a 'super heavily peated' whisky produced by Bruichladdich distillery on Islay, which has a PPM of 128.9!

Although the PPM is a relatively accurate way to determine how smoky a whisky will be to your tastebuds, PPM can be reduced, or retained, throughout the rest of the whisky making process. For example, a slower distillation reduces phenol level, and a wide cut point increases the level. These methods ultimately determine how peaty a whisky will be when it is in the bottle. Meaning, the best way to know how peaty a whisky is, is to put liquid to lips.