How long does home brew beer take to ferment?

This isn't an easy question to answer as every brew will take a different amount of time depending on the ingredients used, temperature ranges involved and type of beer to be brewed. There are also two types of fermentation, primary (in the plastic fermenter) and secondary (in your brew bottles).

Primary fermentation

If you allow at least 7 days and up to about 10 days for your brew to ferment you won't go far wrong with your primary fermentation. Remember though, if the air lock is still bubbling, your beer has not finished fermenting.

A more accurate way to determine whether primary fermentation has finished is to use a hydrometer to check the gravity hasn't changed. Once the gravity remains constant throughout the fermentation process, you can start secondary fermentation.

Secondary fermentation

The secondary fermentation time (time in the bottles) usually takes at least 14 days but the longer you can leave your brew in the bottle the better. Remember to keep your bottles nice and cool (a cellar is as good a place as any).

All in all, the total time your home brew beer should take to ferment, including primary and secondary fermentation, is at least 21 days.