How to use WHILE/WHILST, WHEN, WHEREAS

While or whilst?

While and whilst mean the same when we use them as conjunctions. They both mean ‘during the time that something else happens’, or ‘in contrast with something else’.

While is much more common than whilst, and whilst sounds more formal:

Would you like something to eat while we’re waiting? (less common: … whilst we’re waiting?) (during the time we’re waiting)

While or when?

While (or whilst) means ‘during the time when something else happens’. When can mean the same as while, but when can also refer to a point in time.

 

Compare

during the time something happens	a point in time
The phone rang while/when we were having dinner.	When the phone rang, she answered it immediately. Not: While the phone rang …

 

While as a noun

A while means ‘an unspecified period of time’:

We spent a while looking at the boats in the harbour before going for lunch.

I haven’t seen Andrew for a while. I wonder if he’s okay.

It’s a long while since anyone lived in that house – maybe ten years. It’s a ruin now.

 

Typical error

• While does not mean the same as when:

Always keep some change with you. It’s useful when buying a bus ticket.

Not: … while buying a bus ticket.

When I came home, I made some dinner then watched TV.

Not: While I came home …

Whereas

We use the conjunction whereas to indicate a contrast between two facts or ideas:

He loves foreign holidays, whereas his wife prefers to stay at home.

Whereas most new PCs have several USB slots, older ones often only had one.

Warning:

Whereas means the same as while in sentences expressing contrasts. It does not mean the same as while when while refers to time:

The south has a hot, dry climate, whereas/while the north has a milder, wetter climate.

The secretary took care of my appointments while I was away from the office.

Not: … whereas I was away from the office.

Want to learn more grammar? Book a live lesson!