The pH of coffee can range from 4.5 to 5.5, which is lower than the neutral pH of 7.

Here's why:

* Coffee beans contain chlorogenic acid, which breaks down during roasting and contributes to the coffee's acidity.

* Other acids present in coffee include citric acid, malic acid, and quinic acid.

* The brewing method can also affect acidity. For example, drip coffee tends to be more acidic than French press coffee.

While coffee's acidity is a key part of its flavor profile, it can be problematic for some people with sensitive stomachs.