We use formal English in serious situations, when applying for a job, essays for school and with people we don’t know well.
Informal English is used with friends, relatives and on social media mostly.
Formal English is more common when writing, informal English is more common when we speak.
formal: I have decided to refuse his offer.
informal: I’ve decided to refuse his offer. (informal: I’ve=contraction)
formal: The person whom I met in Ireland was very friendly.
informal: The person I met in Ireland was very friendly.
(informal: relative clause without the relative pronoun whom)
formal: I ate your cake this afternoon.
informal: Ate your cake this afternoon.
formal: apologize
informal: say sorry
formal: as soon as possible
informal: ASAP
Usage of modal verbs
Can I offer you something new? (neutral)
May I offer you something new? (more formal)
Might I offer you something new? (very formal)
Examples of Less Formal & More Formal Expressions
Less Formal More Formal
a lot of many, much, numerous, a great deal of
about regarding
after that thereafter
also / plus moreover
answer respond
ask for request
at first initially
better superior, improved
breathing respiration
buy purchase
cheap inexpensive
drink beverage
eat consume
end terminate, complete
enough sufficient
fix repair
get obtain, acquire
help assist, assistance
home residence
in the end finally, ultimately
I've got to / I have to I must, It is necessary for me to
kind of / sort of rather, somewhat
leave depart
let permit
live reside
lively animated
need require, necessity/requirement
next/later subsequently
OK / all right acceptable, satisfactory
old elderly
people persons, individuals
people say that… it is said that…
right away immediately
seem appear
show demonstrate
so therefore, thus, consequently
start begin, commence
start again resume
stop cease
sweat perspire, perspiration
tell inform
that's why therefore
try attempt
very, really quite
want desire, would like, wish
watch observe
whole entire
work function
wrong incorrect
you (generic) one, everyone