The fewer vs. less debate may seem like one of those debates that end in a standstill. They mean the same thing, don’t they? Believe it or not, they don’t! According to oxforddictionaries.com, fewer is used when referring to people or things in the plural. For example, people are buying fewer magazines.
Less is used when referring to something that can’t be counted or doesn’t have a plural like air, coffee, and money. For example, people want to spend less time waiting for their order.
The NY Times After Deadline Blog says that, “The basic rule for precise use of ‘less’ and ‘fewer’ is simple (though we slip often). Use ‘fewer’ with countable, individual things, and ‘less’ with uncountable amounts, volumes, etc. So: ‘I should drink less coffee,’ but ‘I should eat fewer doughnuts.’”