“Not that I know of” is a cautious negative answer: based on what I know, I have no reason to think the answer is yes. It is useful when someone asks whether an event, problem or change exists but you cannot personally verify every relevant fact. To prevent misunderstanding, add what you checked, the limits of your information and, when necessary, who can verify it.
The key is not to turn a reasonable answer into a promise of universal certainty. “Not that I know of” does not mean “definitely not,” and it does not automatically mean “I refuse to answer.” It tells the other person that your knowledge has boundaries. If the stakes are high, that boundary belongs in the next sentence.
- Use the phrase when you have some information but cannot rule out all possibilities.
- Say what your answer covers: the class, the timetable, the current report or your own observations.
- Distinguish no confirmed evidence from proof that nothing happened.
- Identify who has the authoritative record if a decision depends on certainty.
- Do not use an uncertain answer to conceal a known problem.
What the expression actually means
Cambridge Dictionary defines not that I know of as an answer meaning no, judged from the information available to the speaker. The phrase therefore combines a negative conclusion with a knowledge limit. It is not merely a stylish way to say no. Its caution is part of the message.
Imagine a colleague asks, “Has the presentation room changed?” The response “No” might sound definitive, though you checked only yesterday’s invitation. “Not that I know of; the invitation still names Room 4, but I haven’t seen today’s update” is more informative. The answer gives a likely current understanding while identifying what remains unverified.
English has many ways to show different degrees of commitment to a statement: “Definitely not,” “I haven’t seen that,” “I don’t think so,” “As far as I’m aware,” and “Not that I know of.” Those expressions are not interchangeable in every setting. Saying what your evidence covers is often more important than choosing a particular hedge.
The communication mechanism: answer, scope, route
A useful repair has three parts. First, give the answer that is justified by what you know. Second, state the scope of your knowledge: the time, source, place or people you can actually speak about. Third, give a verification route if the listener must act on the answer.
In ordinary conversation, speakers often leave background information unspoken because they assume it is shared. That is efficient when the question is low-stakes. It becomes dangerous when a listener silently upgrades a limited answer into an absolute guarantee. The speaker can prevent that upgrade with a brief addition: “Not that I know of, but I haven’t checked today’s list.”
The listener can help too. Instead of arguing, “So you’re certain?”, ask a question with a practical purpose: “Have you checked the latest schedule, or is that from yesterday?” A factual follow-up is not an accusation; it identifies which information the next action requires.
Worked dialogue 1: a class event
Fictional example. Two pupils are preparing for a school activity. One believes the venue may have changed after a weather update.
Siti: “Has the practice moved to the hall?”
Jon: “Not that I know of. Our teacher’s last message still said the classroom.”
Siti: “Was that from today?”
Jon: “Yesterday. I’ll check the latest class notice before we go.”
Jon’s answer is useful because he names the actual source and its date. He neither invents a change nor guarantees that no change has occurred. Siti’s follow-up tests the piece of information that matters: whether the available notice is the current one.
A weaker exchange would be “No, I don’t think so,” followed by everybody walking to the wrong place. The problem would not be politeness; it would be treating one person’s incomplete knowledge as final logistics. The better exchange makes the missing check visible.
Worked dialogue 2: a family concern
Fictional example. A parent asks another adult whether a child is upset about an upcoming change.
Parent: “Is Priya worried about the move?”
Aunt: “Not that I know of, but we haven’t discussed it directly.”
Parent: “Thanks. I’ll ask her how she’s feeling rather than assume.”
The aunt is not entitled to declare the child’s private feelings. She can responsibly report what she does and does not know. The parent’s next step is to speak with the person concerned, not to treat an indirect impression as a diagnosis.
The same caution applies to classmates and colleagues. Saying “I haven’t heard them complain” is not evidence that no problem exists. The answer must distinguish your observations from another person’s inner experience.
Worked dialogue 3: a project handover
Fictional example. A team member asks whether an issue remains unresolved before a handover.
Ravi: “Are there any outstanding access problems?”
Leila: “Not that I know of in the issues I reviewed this morning. I haven’t checked the security team’s queue.”
Ravi: “Then I’ll mark your queue checked, not the whole system cleared, and ask security to confirm theirs.”
The team maintains an accurate boundary between a local check and a system-wide statement. Leila’s answer is neither a complete failure nor a final approval. Ravi converts the limited answer into appropriately limited action. This is useful in teamwork because records often outlive the conversation that produced them.
Worked dialogue 4: a customer asks about a restriction
Fictional example. An employee is asked whether an item can be brought into a venue. The employee knows usual practice but not the current event-specific condition.
Visitor: “Is there a restriction on large bags?”
Employee: “Not that I know of under the usual rules, but this event may have additional conditions. Please check the organiser’s entry notice.”
This is not an excuse to avoid responsibility. If the employee has access to the definitive rule, checking it is more useful than repeating a hedge. When the rule affects entry, payment, safety or personal information, the source should be verified before the visitor relies on the answer.
Did You Know? A negative answer can be narrower than it sounds
“Not that I know of” contains a built-in reference to the speaker’s knowledge. It is possible for the answer to be sincere and still incomplete. That is why the same phrase may be appropriate for an informal question about a changed plan but insufficient as the sole basis for a high-stakes compliance decision. What matters is not the speaker’s confidence alone; it is whether the listener’s next action demands stronger evidence.
Register and tone: from conversational to formal
- Informal: “Not that I know of.” Natural when the subject is familiar and the cost of error is small.
- Informal with a limit: “Not that I know of—I only saw yesterday’s message.” Better when plans may have changed.
- Neutral workplace: “I’m not aware of any reported issue in the tickets assigned to our team.” Makes the information boundary explicit.
- Formal record: “No issue was identified in the records reviewed as of [specified date]. The review did not cover [specified area].” Reports what the review established without overclaiming.
- Sensitive personal question: “I don’t know enough to answer for that person. It would be better to ask them directly.” Protects another person’s perspective.
Avoid hiding uncertainty behind grand language. A long formal sentence can still be misleading if it fails to name the source. In an ordinary conversation, a short phrase followed by the specific limitation is often more responsible than a polished statement of false certainty.
Misconceptions and common repairs
- Misconception: The phrase proves the answer is no. Repair: it reports a negative judgment based on available knowledge.
- Misconception: It means the speaker must be concealing something. Repair: evaluate the information scope before attributing motives.
- Misconception: It means “I don’t care.” Repair: separate uncertainty from indifference.
- Misconception: It is enough for a safety-critical decision. Repair: identify and consult the authoritative source.
- Misconception: A listener may silently substitute “never” for “not that I know of.” Repair: restate the actual limited claim.
Compare three statements: “There is no timetable change,” “I haven’t received a timetable change,” and “Not that I know of.” The first asserts a world fact; the second reports a personal communication fact; the third offers a cautious conclusion. A speaker should choose the statement that the evidence actually supports.
Diagnostic questions for the speaker and listener
The speaker can ask: What have I personally observed? How recent is it? Is there a reliable record? Am I answering about one part or the whole? Does anyone need to act on this information now? The listener can ask: What source supports that answer? What was not checked? Is there someone whose confirmation is still necessary?
These questions are especially important when an answer concerns absent people. Reporting that you have not heard from somebody is different from reporting that they agree. No message, no objection and no known problem are three different kinds of evidence.
Retrieval practice: choose the most responsible reply
Try the following without looking at the answers. Scenario one: you have not heard of a room change but the latest notice may be newer than your copy. Scenario two: someone asks whether a friend is unhappy, and you have not asked them. Scenario three: you checked your part of a project but not the whole team’s records.
- Suggested answer 1: “Not that I know of. I checked yesterday’s notice, but let’s confirm today’s location.”
- Suggested answer 2: “Not that I know of, but I can’t speak for them. You could ask them directly.”
- Suggested answer 3: “I’m not aware of any issue in my section. The other team’s review is still needed.”
Change the scenario and practise again after a day. Replace “room change” with “price change” or “delivery change.” Your goal is to retrieve the three-part method—answer, scope, route—without needing to recite exactly the same sentences.
How students, parents and teachers can help
Students can practise by comparing sentences that report observation with sentences that claim certainty. Ask them to underline evidence words such as “I saw,” “I checked,” “the record shows,” and “as of yesterday.” Then ask what additional information would make the answer reliable enough for action.
Parents can model uncertainty without making children feel that every question is unanswerable. A calm “I don’t know whether that event has changed; let’s check the notice” combines intellectual honesty with a practical next step. Avoid treating admission of uncertainty as incompetence.
Teachers can provide fictional mini-dialogues in which the speaker has only a partial source. Learners identify the unknown part and compose a one-sentence clarification. This focuses on usable communication rather than rote dictionary definitions. The British Council’s guidance on checking comprehension similarly highlights questions that reveal understanding rather than simply inviting an automatic yes.
Transfer the skill across school, home and adult life
In school, the unknown may be a changed classroom. At home, it may be another person’s preferences. In adult life, it may be a booking condition, payment status or workplace risk. The common mechanism is to separate what the speaker knows from what the world definitely contains, and then determine whether a further check is necessary.
The broader subject is part of How English Works | Conversation and Repair. For language learners investigating how meanings and expressions are acquired, see the established What Is Vocabulary? reference. These are supporting guides, not replacements for the specific communicative job here.
Frequently asked questions
Is “not that I know of” a firm no?
No. It indicates a negative answer relative to the speaker’s available knowledge. The stronger claim “definitely not” requires stronger evidence.
Does it mean the same as “no comment”?
No. “No comment” generally declines to provide a substantive answer. “Not that I know of” supplies a tentative negative answer, albeit with a knowledge limit.
Can it be used in a formal email?
Yes, but in formal records a more specific expression such as “No issue has been reported to this team as of [date]” may be more useful. State the scope of the check.
What if somebody challenges my limited answer?
Offer the source and limitation instead of becoming defensive: “I checked the list I have; I haven’t checked the updated version yet.”
A simple closing rule
Say only what your evidence allows, make your knowledge boundary visible, and check the authoritative source before the answer controls an important decision. That is how a short, cautious no can remain both helpful and trustworthy.
Language references: Cambridge Dictionary: Not that I know of; British Council: Checking comprehension. All dialogues are invented educational demonstrations, not observed outcomes.