COULD = reasonably probable possibility or polite permission: "Could you help me?" / "It could rain." MIGHT = more remote or uncertain possibility: "It might rain" (less likely than COULD). For permission: COULD is more natural than MIGHT in modern English. "Could I leave early?" (polite permission). "Might I ask a question?" (very formal, archaic).
COULD — MAIN USES: (1) PAST OF CAN (ability): "When she was young, she could run very fast." (2) POLITE PERMISSION (present): "Could I use your office for the call?" (more polite than "Can I?"). (3) POSSIBILITY IN PRESENT OR FUTURE: "The project could be delayed." "That could be a problem." (4) SUGGESTION: "You could try a different approach." (5) POLITE REQUEST: "Could you send me the file?" COULD is the past form of CAN but in many uses does not denote past — it is simply more tentative and polite than CAN. COULD vs CAN for permission: "Can I help you?" = informal/direct. "Could I help you?" = more formal and polite. COULD HAVE + participle: past possibility: "It could have been worse."
Could you arrange for the updated contract to be sent to the client's legal team by the end of the working day? They have indicated that they would like the opportunity to review it before the scheduled signing meeting tomorrow morning.
Could I ask a clarifying question before we move on to the next agenda item? I want to make sure I have correctly understood the proposed change to the approval process before we begin discussing the implementation timeline.
The delay in receiving the final data set could have a significant impact on the publication timeline, as the analysis cannot be completed until all the relevant figures from each of the regional offices have been submitted and validated.
MIGHT — MAIN USES: (1) REMOTE OR UNCERTAIN POSSIBILITY: "She might be in a meeting" (less certain than "She could be"). "The flight might be delayed" (high uncertainty). MIGHT vs MAY: both express possibility, but MIGHT = slightly less probable than MAY in formal English. In practice, they are interchangeable for many speakers. (2) MIGHT HAVE + participle: unachieved or uncertain past possibility. "She might have left already." "I might have misunderstood." (3) CAUTIOUS CRITICISM OR SUGGESTION (often with "you"): "You might want to reconsider that approach" (very diplomatic, a gentle criticism). "You might at least have warned us" (cautious criticism). (4) PERMISSION (very formal, archaic): "Might I suggest an alternative?" (extremely formal, almost literary). MIGHT + NOT: "She might not attend" (uncertainty, may not).
The integration process might take longer than originally projected if the technical teams encounter compatibility issues between the legacy system and the new platform, a risk that has been flagged in the project risk register but not yet fully quantified.
You might want to consider obtaining independent financial advice before committing to the proposed terms of the agreement, given the complexity of the payment structure and the long-term financial obligations that would be incurred.
We should acknowledge that we might have been too optimistic in our initial assessment of the market penetration rates, and it may be necessary to revise the sales projections downward for the first two quarters of the financial year.
Common mistake
THE MAIN CONFUSIONS: (1) MIGHT for permission in modern English: "Might I use your office?" = sounds very archaic. In modern English: "Could I use your office?" or "May I use your office?" for permission. (2) COULD vs MIGHT for possibility: COULD = reasonably probable or general possibility. MIGHT = more remote or uncertain possibility. "She could be at the airport" (quite possible). "She might be at the airport" (less certain, more doubtful). (3) MIGHT NOT vs MUSTN'T: "She might not attend" = she may not attend (uncertainty). "She mustn't attend" = she must not attend (prohibition). Completely different meanings. (4) COULD HAVE vs MIGHT HAVE: "He could have done it" = he had the capacity/possibility (did not necessarily do it). "He might have done it" = he may have done it (uncertainty about whether it happened).
Trick to remember it
POSSIBILITY SCALE (from most to least probable): WILL (almost certain) > SHOULD (expected) > MAY (possible) > COULD (possible, reasonably viable alternative) > MIGHT (possible but uncertain, remote). For POLITE PERMISSION: CAN (informal) > COULD (polite/formal) > MAY (very formal) > MIGHT (archaic). DIPLOMATIC SUGGESTION: "You might want to..." = the softest possible way to make a recommendation or criticism in professional English.
Quick rule
COULD = reasonably probable possibility + polite permission + past of CAN. MIGHT = more remote/uncertain possibility + very diplomatic suggestion/criticism. For permission: COULD or MAY (not MIGHT in modern English). "Could I...?" = polite. "Might I...?" = archaic. "You might want to..." = cautious diplomatic suggestion.
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 to express possibility or permission, with nuances of politeness and degree of certainty. This evolution of past forms acquiring present meaning (or expressing greater politeness/tentativeness) is one of the most fascinating phenomena in the English modal system. Medieval English used these forms more systematically in a temporal sense: "might" was literally the past of "may" and was used to report what someone could or should do in the past. Today, "He said she might attend" is the only context where MIGHT clearly denotes future from a past perspective (future in the past in reported speech). In all other contexts, MIGHT has almost entirely lost its original temporal value to become a marker of uncertainty or remote possibility.
Exercise 1 · Pick the right one
The engineering team has flagged that the new data processing algorithm _____ produce unexpected results in edge cases that were not covered during the initial testing phase, and recommends running further stress tests before deployment.
Exercise 2 · Pick the right one
"_____ I take a few minutes to present the alternative proposal we have developed, before the committee reaches its final decision on the main motion?" the delegate asked the chair at the close of the formal proceedings.
Exercise 3 · Form the word
COULD = reasonably probable possibility + polite permission + past of CAN. MIGHT = more remote/uncertain possibility + very diplomatic suggestion/criticism. For permission: COULD or MAY (not MIGHT in modern English). "Could I...?" = polite. "Might I...?" = archaic. "You might want to..." = cautious diplomatic suggestion.
THE MAIN CONFUSIONS: (1) MIGHT for permission in modern English: "Might I use your office?" = sounds very archaic. In modern English: "Could I use your office?" or "May I use your office?" for permission. (2) COULD vs MIGHT for possibility: COULD = reasonably probable or general possibility. MIGHT = more remote or uncertain possibility. "She could be at the airport" (quite possible). "She might be at the airport" (less certain, more doubtful). (3) MIGHT NOT vs MUSTN'T: "She might not attend" = she may not attend (uncertainty). "She mustn't attend" = she must not attend (prohibition). Completely different meanings. (4) COULD HAVE vs MIGHT HAVE: "He could have done it" = he had the capacity/possibility (did not necessarily do it). "He might have done it" = he may have done it (uncertainty about whether it happened).
POSSIBILITY SCALE (from most to least probable): WILL (almost certain) > SHOULD (expected) > MAY (possible) > COULD (possible, reasonably viable alternative) > MIGHT (possible but uncertain, remote). For POLITE PERMISSION: CAN (informal) > COULD (polite/formal) > MAY (very formal) > MIGHT (archaic). DIPLOMATIC SUGGESTION: "You might want to..." = the softest possible way to make a recommendation or criticism in professional English.
Bryan López
Founder of SpeakUP Academy