Significant vs That's important

When to use each in English, with meaning, register, and examples.

Significant

Top 1,000 (very common) B2 adjective

That's important

Top 3,000 (common)

Most common: Significant

	Significant	That's important
Pronunciation	🇬🇧 /["/sɪɡˈnɪfɪkənt/"]/ 🇺🇸 /["/sɪɡˈnɪfɪkənt/"]/	🇬🇧 //ðæts ɪmˈpɔːtənt// 🇺🇸 //ðæts ɪmˈpɔrtənt//
Meaning	Important or meaning a lot.	This matters a lot.
Example	The research showed a significant improvement in patient outcomes.	It's crucial to remember that **that's important** in our discussion.
Register	Neutral	Neutral
How common	Top 1,000 (very common)	Top 3,000 (common)
CEFR level	B2	-
Part of speech	adjective
Collocations	be, prove, become, extremely, fairly, very, for, to	that's crucial, that's significant, that's essential, that's vital, that's necessary
Antonyms	insignificant, trivial, minor	-
Common mistakes	Confusing 'significant' with 'significance'., Using 'significant' as a noun instead of an adjective., Overusing 'significant' in casual speaking.	Using it in overly formal contexts., Confusing 'that's important' with 'that's necessary', which may imply obligation.
Usage notes	Used in academic and formal contexts to indicate importance. Avoid in very casual conversations; instead, use simpler words like 'big' or 'important'.	Use when emphasizing the significance of something. Appropriate in both casual and serious conversations.

See it in real clips

But of all these anomalies, the most significant is this:

But what is significant is, I felt the touch of God.

But of all these anomalies, the most significant is this:

But what is significant is, I felt the touch of God.

Significant

Because that's important, Kay. Because what's important is that

That's important

Frequently asked questions: Significant vs That's important

What's the difference between Significant and That's important?

Significant: Important or meaning a lot. That's important: This matters a lot.

Which is more common: Significant and That's important?

Significant is the most common in everyday English.

Can you show an example of each?

Significant: The research showed a significant improvement in patient outcomes. That's important: It's crucial to remember that **that's important** in our discussion.

Can I use Significant and That's important interchangeably?

Not always. Significant and That's important are related and overlap in some contexts, but they differ in register, how common they are, and usage, so swapping one for another can change the meaning or tone. Check the differences above before substituting.