is when

USAGE SUMMARY

The phrase "is when" is correct and usable in written English.
It is typically used to introduce a clause that explains a certain point in time or situation. For example: "The moment when I knew I wanted to become a doctor is when I volunteered at the local health clinic."

✓ Grammatically correct

News & Media

Wiki

Human-verified examples from authoritative sources

Exact Expressions

60 human-written examples

Which is when?

The New Yorker

The question is when.

The New York Times

When is when?

The New Yorker

The great unknown is when.

The Economist

Which is when it's done.

The New York Times - Magazine

It is when," he said.

The New York Times - Science

That is when it sucks.

The New Yorker

The only question is when.

The New York Times

What nobody knows is when.

The Economist

That is, when it's true.

The New York Times

This is when accidents happen.

The New York Times - Books

Expert writing Tips

Best practice

Use "is when" to clearly define a specific moment or condition that triggers an event or state. For example, "Success is when preparation meets opportunity."

Common error

Avoid using "is when" in formal definitions where a more precise term is needed. Instead of "A recession is when the economy declines", use "A recession is a period of economic decline."

Linguistic Context

The phrase "is when" primarily functions as a linking verb connecting a subject to a clause that specifies a time or condition. According to Ludwig, the phrase introduces a clause explaining a specific point in time or situation, and the examples from news and media sources illustrate this use.

Expression frequency: Very common

Frequent in

News & Media

68%

Wiki

10%

Science

8%

Less common in

Formal & Business

7%

Encyclopedias

0%

Reference

0%

Ludwig's WRAP-UP

The phrase "is when" is a common and grammatically correct way to specify a time or condition. Ludwig AI confirms its role in introducing clauses that explain specific moments or situations. Predominantly used in news and media, as well as in wiki contexts, this phrase serves to clarify events and their timing. While appropriate for various writing styles, it's best to avoid using "is when" in formal definitions. Alternatives like "occurs when" or "happens when" can provide variety, but "is when" remains a straightforward and widely accepted choice.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

occurs when

Changes the verb to "occurs", emphasizing the happening of an event.

happens when

Replaces "is" with "happens", focusing on the event taking place.

that is the time

Expands the phrase to a longer description, specifying a particular time.

that is the moment

Focuses on a specific moment, adding emphasis to the importance of time.

that's the point

Uses "that's" to shorten the statement and focus on a specific point.

it is at this moment

Rephrases to emphasize the specific moment of the event.

this is the occasion

Emphasizes a particular event or gathering.

this is the juncture

Uses "juncture" to refer to a critical point in time.

this is the instance

Replaces "when" with "instance" to pinpoint a specific occurrence.

the time is ripe

Uses a metaphoric expression emphasizing the suitability of a certain time.

FAQs

How can I use "is when" in a sentence?

The phrase "is when" is used to define a time or circumstance. For example, "The best time to plant a tree "is when" it's raining."

What are some alternatives to "is when"?

You can use phrases like "occurs when", "happens when", or "that is the time" instead of "is when", depending on the context. For example, "The problem "occurs when" the system is overloaded."

Is it grammatically correct to start a sentence with "is when"?

While it's not typical to start a sentence with "is when", it's grammatically acceptable in certain contexts, particularly when emphasizing a specific point. A more common structure involves placing "is when" within the sentence. For example, "That "is when" it all started."

What's the difference between "is when" and "is where"?

"Is when" refers to a specific time or circumstance, while "is where" refers to a location or place. For example, "The conference "is where" all the experts meet", and "The deadline "is when" all submissions are due."