
'Could' expresses reasonable possibility or polite permission; 'might' expresses more remote or uncertain possibility.
Use "could" to ask for permission in a polite but fairly direct way. It works well when you expect a positive answer with reasonable confidence.
Could you pass me the salt, please? I cannot reach it from here.
Could I borrow your charger for a minute? My phone is almost dead.
Could you speak a little more slowly, please? I am still learning English.
"Might" sounds more hesitant and uncertain than "could". Use it when you are unsure whether you will be allowed, or when you want to sound especially considerate.
It might rain later, so you might want to bring an umbrella just in case.
You might want to call ahead before going, the restaurant closes early on Mondays.
We might be late if there is heavy traffic on the motorway.
Common mistake
"Might I use your office?" sounds archaic in modern English. For formal permission use "Could I" or "May I". And "might not" and "mustn't" are not the same: "She might not attend" = she may not attend (uncertainty). "She mustn't attend" = she must not attend (prohibition).
Trick to remember it
Quick rule
Did you know?
"Could" and "might" are both past forms of modals: "could" is the past of "can" and "might" is the past of "may". But in modern English, both are used primarily in the present for possibility or permission. This evolution of past forms acquiring present meaning (or greater politeness) is one of the most fascinating phenomena in the English modal system. The only context where "might" clearly denotes future-from-a-past-point is reported speech: "He said she might attend."
Exercise 1 · Pick the right one
"_____ I leave a bit early today? I have a dentist appointment."
Exercise 2 · Pick the right one
"_____ I ask who's calling, please?" (formal phone etiquette)
Exercise 3 · Form the word
'Can' expresses ability in the present; 'be able to' is the necessary alternative when 'can' cannot be used.
'Could you...?' asks if someone is able to do something; 'would you...?' asks if they would be willing to.
'A' is used before consonant sounds; 'an' is used before vowel sounds.
'A lot of' works for countable and uncountable; 'many' only for countable; 'much' only for uncountable.
Bryan López
Founder of SpeakUP Academy