Could vs. Would
Main DifferenceAlthough both ‘Could’ and ‘Would’ are Auxiliary Verbs in English Grammar and serve to modify the mood of a verb, they often confuse the learners to where and how to use them. To cope with such issue and to get an explicit idea about these Model Verbs, the underlying illustration would be of good help. First of all, we would take ‘Could’ into a discussion. Could is basically a ‘second form of can’ and is used to indicate a capability in the past e.g. ‘I could run faster in my childhood’ or ‘I could catch the thief when I saw him at first’. Hence, it replaces ‘Can’ for the past sentence; however, not only as past, it can be used in place of ‘can’ in the Present Tense to give the phrase a conditional tone such as ‘She could not allow her son to go out in the dark’. Thirdly, ‘Could’ also works to make a request more polite. For example, ‘could you let me know what your intentions are’? On the other hand, ‘Would’ is also a Model Verb and has a differential job. Firstly, it is used to indicate future in the past e.g. ‘She would try to work hard following the example of her brother’. Secondly, ‘Would’ works as the conditional mood of ‘will’ in the conditional sentences such as ‘I would get you a car if you followed my advice’. In a subjunctive case would is utilized to indicate an unreal condition e.g. ‘I would work more efficiently if I were you’. Thirdly, ‘Would’ is used for polite requests but with a questioning tone unlike ‘could’ e.g. ‘Would you like to let me know what had happened’? Moreover, ‘would’ is also used for Future Tense when there is a probability but not complete certainty e.g. ‘He would help you’ [there is a possibility that the third person will help.

Difference Between Could and Would
Could vs. Would
Would is considered as the past form of ‘Will’ to indicate future in the past; ‘Could’ is the past form of ‘Can’ to indicate capability in the past.
Could vs. Would
Could is used to suggest; Would is used in conditional sentences.
Could vs. Would
'Could' can be used for polite requests; Would can be employed to raise a polite question.
Could vs. Would
Could is used for possibility, while Would is used for less probability.
Could vs. Would
Would can be adopted to indicate unreal thing; Could is not used for unreal things.
Couldverb
conditional of can
Wouldverb
(heading) As a past-tense form of will.
Couldverb
Used as a past subjunctive (contrary to fact).
I think he could do it if he really wanted to.I wish I could fly!Wouldverb
(obsolete) Wished, desired (something).
Couldverb
Used to politely ask for permission to do something.
Could I borrow your coat?Wouldverb
(archaic) Wanted to ( + bare infinitive).
Couldverb
Used to politely ask for someone else to do something.
Could you proofread this email?Wouldverb
Used to; was or were habitually accustomed to ( + bare infinitive); indicating an action in the past that happened repeatedly or commonly.
Couldverb
Used to show the possibility that something might happen.
We could rearrange the time if you like.Wouldverb
Used with bare infinitive to form the "anterior future", indicating a futurity relative to a past time.
Couldverb
Used to suggest something.
You could try adding more salt to the soup.Wouldverb
(archaic) Used with ellipsis of the infinitive verb, or postponement to a relative clause, in various senses.
Couldnoun
Something that could happen, or could be the case, under different circumstances; a potentiality.
Wouldverb
Was determined to; loosely, could naturally have been expected to (given the tendencies of someone's character etc.).
Wouldverb
(heading) As a modal verb, the subjunctive of will.
Wouldverb
Used to give a conditional or potential "softening" to the present; might, might wish.
Wouldverb
Used as the auxiliary of the simple conditional modality (with a bare infinitive); indicating an action or state that is conditional on another.
Wouldverb
Might wish ( + verb in past subjunctive); often used in the first person (with or without that) in the sense of "if only".
Wouldverb
Used to impart a sense of hesitancy or uncertainty to the present; might be inclined to. Now sometimes colloquially with ironic effect.
Wouldverb
Used interrogatively to express a polite request; are (you) willing to …?
Would you pass the salt, please?Wouldverb
Might desire; wish (something).
Wouldnoun
Something that would happen, or would be the case, under different circumstances; a potentiality.
Comparison Chart
Could | Would |
Usage | |
‘Could’ is the past form of ‘Can’ to indicate capability in the past | Considered as the past form of ‘Will’ to indicate the future in the past |
Language | |
Suggestion | Conditional sentences |
Extra Uses | |
Polite requests | Polite questions |
Adoption | |
Can be adapted to indicate an unreal thing | Cannot be used for unreal things |
Definition of Would
Would is a Model Auxiliary Verb works to modify the mood of the main verb in the sentence. It is usually used in conditional sentences as it depends on some conditions. Would also be used for sentences in which something is being said about the future but in the context of the past. This model verb can also be employed to raise polite questions as well.
Definition of Could
Could is a Model Auxiliary Verb and normally used in place of ‘Can’ for Past Tenses to highlight past capability. Apart from showing capability in the past, ‘Could’ is also used frequently to make polite requests. It is used for possibility e.g. ‘they could have done this job more effectively’.