Wordplay©
Grammar clinic

Less and fewer mean the same thing – they both describe a reduced quantity. However, they each have their own place, and they are not interchangeable.

If the quantity is made up of units you can count – people, books, cars - then you should use ‘fewer’.

You can count people, so you would say: Fewer people read The Guardian than read The Sun.

If your quantity relates to something you can’t count – like air, water, or pain, you use ‘less’.

So: He is in less pain now. There is less water in that bottle than in that one. 

NB: Supermarkets get this wrong at the checkout. ‘Eight items or less’ is grammatically incorrect – but it fits in a shorter space and sounds less formal than ‘eight items or fewer’.

Less and fewer with percentages

When your percentage describes groups/things you can count, you use ‘fewer’. For example:

‘The report revealed that fewer than 28 percent of schoolchildren regularly eat a family meal.’

This is because you can count the number of respondents to a survey/report.

If the percentage describes things that can’t be counted, then you use ‘less’. For example:

‘Government research shows that less than 30 percent of total UK petroleum consumption is domestic.’

This is because petroleum consumption is an ongoing action, rather than an entity that you can point your finger at and count.

This is also the case when you are talking in terms of statistics. For example:

‘The contraceptive pill has a failure rate of less than two percent.’

This is because ‘failure rate’ is a state of being or a likely outcome – you can’t count it.