Used and loved by millions
Since I tried Ludwig back in 2017, I have been constantly using it in both editing and translation. Ever since, I suggest it to my translators at ProSciEditing.

Justyna Jupowicz-Kozak
CEO of Professional Science Editing for Scientists @ prosciediting.com
day of when
Grammar usage guide and real-world examplesUSAGE SUMMARY
The phrase "day of when" is not correct and not usable in written English.
It seems to be an incorrect combination of words that does not convey a clear meaning or context. Example: "I remember the day of when we first met."
⚠ May contain grammatical issues
News & Media
Science
Table of contents
Usage summary
Human-verified examples
Expert writing tips
Linguistic context
Ludwig's wrap-up
Alternative expressions
FAQs
Human-verified examples from authoritative sources
Exact Expressions
7 human-written examples
But anyone who has ever braved the crowds to shop there the day before Yom Kippur -- not to mention the day of, when the store remains open -- knows that the bulk of the business is walk-in.
News & Media
"Even the day of, when we're filming, someone will have a good idea," said Mr. Baxter, who has helped construct anthropomorphic ears of corn and ice cream cones, among other things, for "Food Party".
News & Media
Mr. Giuliani said watching the documentary stirred the most disturbing memories of that day: of when he pulled up next to the north tower and saw people jumping to the ground around him.
News & Media
I knew little about marriage before I got married, not having even contemplating it until the day of when my then partner asked me to meet her at city hall in San Francisco to get married.
News & Media
On the day of when Flora made landfall, advisories recommended all citizens on beaches and in low-lying areas west of Santo Domingo to evacuate.
Wiki
In these cases, it is still safe to assume that the fish died within a day of when it was last seen alive because living fish were rarely missed when surveying the stream.
Science
Human-verified similar examples from authoritative sources
Similar Expressions
52 human-written examples
Had the day of days when everything clicked but also showed enough to indicate it was not all a fluke.
News & Media
This effect was variable over the 5 days, but was generally most notable on the day of introduction, when both the short and daily trends were positive.
The plant inside the greenhouse captured less than 1.0 g/m2 day of CO2 when ventilation is used, whereas it captured nearly 52 g/m2 day of CO2 when alternative cooling is used.
Their new year is the first day of spring, when the light comes and the days are longer.
News & Media
They chose a day of reflection, when many were thinking of peace forgiveness, thinking about others.
News & Media
Expert writing Tips
Best practice
Avoid using the phrase "day of when" in formal writing. Opt for grammatically correct alternatives such as "the day when" or "the day that" to ensure clarity and professionalism.
Common error
A common mistake is adding "of when" after "day". It's generally redundant. Choose either "the day when" or "the day that" to maintain grammatical correctness and avoid awkward phrasing.
Source & Trust
81%
Authority and reliability
1.8/5
Expert rating
Real-world application tested
Linguistic Context
The phrase "day of when" functions as a temporal conjunction, attempting to connect a specific day with a related event or condition. However, according to Ludwig AI, the phrase is grammatically incorrect, representing a flawed attempt to specify time.
Frequent in
News & Media
40%
Science
40%
Wiki
20%
Less common in
Formal & Business
0%
Academia
0%
Reference
0%
Ludwig's WRAP-UP
In summary, the phrase "day of when" is generally considered grammatically incorrect. While it appears in some contexts, particularly in news, media, and scientific sources, its usage is not recommended for formal writing. Ludwig AI identifies it as a flawed combination of words. It is advisable to use grammatically correct alternatives like "the day that" or "the day when" to ensure clarity and precision. The low expert rating reflects the phrase's grammatical issues and inconsistencies.
More alternative expressions(10)
Phrases that express similar concepts, ordered by semantic similarity:
the day when
Removes the unnecessary "of", resulting in a more concise and grammatically correct phrase.
the day that
Replaces "of when" with the more grammatically standard "that".
on the day that
Adds "on" for slightly different emphasis.
the day on which
Replaces "of when" with the formal "on which".
during the day that
Specifies that the event happened within the timeframe of a particular day.
the day in which
Offers a more formal alternative to "the day that".
the date when
Substitutes "day" with "date" to emphasize a specific calendar day.
the occasion when
Replaces "day" with "occasion" to denote a specific event.
the time when
Broadens the context from a specific day to a more general time.
the moment when
Focuses on a precise moment rather than a whole day.
FAQs
Is "day of when" grammatically correct?
No, the phrase "day of when" is generally considered grammatically incorrect. It's better to use phrases like "the day "the day that"" or "the day "the day when"".
What are some alternatives to "day of when"?
Alternatives include "the day that", "the day on which", or simply "the day "the day when"". The best choice depends on the specific context of your sentence.
How can I use "the day when" in a sentence?
For example, you could say, "I remember the day "the day when" we first met" instead of "I remember the day of when we first met".
Which is correct, "day of when" or "the day that"?
"The day that" is the correct and preferred phrase. Avoid using "day of when" as it is grammatically questionable. For example, use "the day "the day that" I graduated" instead of "day of when I graduated".
Editing plus AI, all in one place.
Stop switching between tools. Your AI writing partner for everything—polishing proposals, crafting emails, finding the right tone.
Table of contents
Usage summary
Human-verified examples
Expert writing tips
Linguistic context
Ludwig's wrap-up
Alternative expressions
FAQs
Source & Trust
81%
Authority and reliability
1.8/5
Expert rating
Real-world application tested