It can be a conundrum when you’re writing about countable items, time, money, distance and weight. This is an old-school rule, but it hangs around for good reason. When you use the wrong reference it screams out to the reader or audience, “that’s not right!”
I’ll try and keep it simple: if you can count the item you’re talking about (quantity of things), use ‘fewer’. And if the item has changed in volume or mass (but is a singular lump or stuff) use ‘less’.
Quantity that can be counted: fewer.
Lump, mass or stuff: less.
Does that sound simple enough? I think so – but it is amazing how many people default to the use of ‘less’. In speech it’s understandable if you make a blooper. But when you’re writing, you’ve got the time to get it right.
Here are some examples of countable items.
There are fewer trees in the forest.
We had fewer thunderstorms this year.
There were definitely fewer people at Donald Trump’s inauguration compared with Barack Obama’s.
Here are some straightforward examples where less is used for the non-countable item.
I am less concerned than my neighbour about traffic jams, because I catch the train.
The teacher demanded less chatter from the students.
I’m earning less in real terms now than five years ago.
But wait! It wouldn’t be English without an exception to the rule. Although we can count hours and days; dollars; kilometres; and kilograms – we often refer to them as a lump of time, money, distance, or weight. They become singular and therefore use less.
I had to wait less than four weeks for my application to be approved. (The waiting period is singular)
The allowable weight for carry-on baggage is less than 7kg. (The weight limit is singular)
I have less than $1000 in the bank and can’t afford Uber Eats every night. (The bank balance is singular)
It’s less than 15km from my place to the city. (Distance is singular)
Please answer this question in 100 words or less. (Word limit is the singular item).
To keep it clear, remember that countable items use fewer and singular items use less.