The basic difference between a formal and informal letter is that you write an informal letter to someone you either know personally or might want to get to know personally and you write a formal letter to someone you don’t know personally or, for the purposes of the letter at least, won’t ever need to know personally.
Within this broad definition, it is important to say that there is no black and white distinction between ‘formal’ and ‘informal’. The table shows how different recipients may require more or less formal letters on a scale rather than a strict division, with (1), (2) and (3) being generally informal and (4), (5) and (6) being generally formal.
Very informal (1) |
(2) |
(3) |
(4) |
(5) |
Very formal (6) |
Boyfriend Girlfriend etc |
Pen-friend |
Grandparents |
Teacher |
Newspaper or magazine |
Possible employer |
Best friend |
New friend |
Relatives you hardly ever see |
Club leader |
Information bureau |
Solicitor, bank, manager of a business etc |