advice vs advise

The core difference

This pair is one letter apart on the page but a full sound apart in speech, which is the fastest way to keep them straight. Advice ends in a hissing /s/, like ice. Advise ends in a buzzing /z/, like wise. Say your sentence aloud; your mouth already knows which one you meant.

Using advice

It is a thing you can give, take, ignore or ask for — and it is uncountable, so it has no plural. You cannot have three advices; you have three pieces of advice or some advice.

• Can I give you a piece of advice before the interview?
• Against my mother's advice, I bought the flat anyway.
• We took legal advice before signing.

Using advise

It is an action, so it changes form: advise, advises, advised, advising. It commonly takes a person as its object.

• Her accountant advised her to keep every receipt.
• I would advise against travelling on a Friday.
• Please advise us of any change of address.

The test

Try swapping in "suggestion" or "recommend". If suggestion fits the slot, you need the noun advice: her suggestion saved me a fortune. If recommend fits, you need the verb advise: I recommend you read the contract. This works every time, because one is a thing and the other is something you do.

The memory trick

Follow the same pattern you already use for practice/practise and licence/license in British English: the noun takes C, the verb takes S. Advice is a thing, like ice. Advise is an action, like uses.

The edge case

Business writing loves the phrase please advise, standing alone at the end of an email. It is grammatical — advise can be used without an object — but it lands as curt and slightly bureaucratic. Let me know how you would like to proceed does the same job more warmly.

Also watch advisor and adviser: both are accepted spellings for the person. British publications lean towards adviser, American ones towards advisor, and job titles often fix one or the other. Pick one and be consistent within a document.