Quick answer
Ensure means to make certain something happens. Insure means to arrange financial cover against loss. Assure means to tell someone something confidently, to remove their doubt. You ensure a result, insure a car, and assure a person.
The core difference
Three verbs, distinguished by what each takes as its object.
- ensure — make certain: ensure the door is locked.
- insure — cover financially: insure the building.
- assure — remove someone's doubt: I assure you it is safe.
The object test
Assure takes a person — you assure somebody. Insure takes a thing with a monetary value. Ensure takes an outcome or a situation. Asking "what is the object?" resolves nearly every case.
The British insurance term
In British insurance, assurance traditionally covers events certain to happen eventually — life assurance — while insurance covers events that might not, such as fire or theft. That distinction is largely historical now but survives in some product names.
Frequently asked questions
Which one means to make certain?
Ensure. Insure is financial cover; assure is telling a person.
What is the quickest test?
Look at the object. A person takes assure; a valuable thing takes insure; an outcome takes ensure.
What is life assurance?
A British term for cover against an event certain to happen eventually, as distinct from insurance against something that might not.
