one third - singular or plural (2025)

Hello gabmac, and Welcome to the Forum

It can go either way - sometimes context is the determinant factor.

e.g. I have split the people into three groups. One third is safe, the remaining two are not.

e.g. People come in three flavours: one third of them like politics, another third do not, and the remainder don't care.

I think it would be odd to talk of a third of the people in the singular, though I can see the grammatical case for it.

I'd always say a third of the people are safe, rather than a third of the people is safe.

I suspect I take the same line with most countables.

Thanks B of A and TT! I agree - singular feels wrong but not sure if I can trust my ear as the third is singular.

The sentence I am thinking of is: One third of all patients are managed by specialist nurses.

It is always "a third of something"

If the something is plural then so is the verb, if the something is singular then so is the verb

A third of the apple was bad
A third of the apples were bad

There will be cases where the 'of something' is missing, but this can be understood from the context: e.g.

Most politicians voted themselves a pay rise but one-twentieth [implied = politicians] were honest enough to vote against it.

One third of all patients are managed by specialist nurses.

PaulQ said:

It is always "a third of something"

If the something is plural then so is the verb, if the something is singular then so is the verb

A third of the apple was bad
A third of the apples were bad

There will be cases where the 'of something' is missing, but this can be understood from the context: e.g.

Most politicians voted themselves a pay rise but one-twentieth [implied = politicians] were honest enough to vote against it.

One third of all patients are managed by specialist nurses.

Click to expand...

This is interesting, Paul. Thank you.

I think we should add a caveat. Sometimes a collective noun can be treated either as a plural or a singular:

The whole cabinet is behind you
The whole cabinet are behind you

So a third of the cabinet can be either singular or plural.

Similarly a box of apples can be either singular or plural:

A third of the box is rotten
A third of the box are rotten

I don't doubt there are further complexities.