If means on (the) condition that, provided (that), providing (that), presuming (that), supposing (that), assuming (that), as long as...
Unless means something similar to ‘if … not’ or ‘except if’.
The verb forms in the examples are similar to sentences with if: we use the present simple in the unless-clause and shall, should, will, would, can, could, may or might in the main clause.
Examples:
"You can't go on vacation unless you save some money." "If you don't save some money, you can't go on vacation."
"You will feel cold if you don't wear a coat." "You will feel cold unless you wear a coat."
Both if and unless are used to introduce conditional sentences.
Warnings:
We don’t use unless for impossible conditions:
If the government had not raised food prices, there would not have been so many protests.
Not: Unless the government had raised food prices …
We don’t use unless and if together:
We’ll go to the coast tomorrow unless it rains.
Not: We’ll go to the coast tomorrow unless if it rains.
LanguageLearningBase.com (short:llb.re) is an online community for learning foreign languages. It represents an open knowledge base. Every member can share and gain knowledge about a new language.
English Grammar: If or Unless?
If means on (the) condition that, provided (that), providing (that), presuming (that), supposing (that), assuming (that), as long as...
Unless means something similar to ‘if … not’ or ‘except if’.
The verb forms in the examples are similar to sentences with if: we use the present simple in the unless-clause and shall, should, will, would, can, could, may or might in the main clause.
Examples:
"You can't go on vacation unless you save some money."
"If you don't save some money, you can't go on vacation."
"You will feel cold if you don't wear a coat."
"You will feel cold unless you wear a coat."
Both if and unless are used to introduce conditional sentences.
Warnings:
We don’t use unless for impossible conditions:
We don’t use unless and if together: