Then vs Thereafter

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

Then

Top 1,000 (very common) A1 adverb

Thereafter

Formal Beyond 10,000 (less common) C1 adverb

Most formal: Thereafter Most common: Then

	Then	Thereafter
Pronunciation	🇬🇧 /["/ðen/"]/ 🇺🇸 /["/ðen/"]/ Hear Then	🇬🇧 /["/ˌðeərˈɑːftə(r)/"]/ 🇺🇸 /["/ˌðerˈæftər/"]/ Hear Thereafter
Meaning	At that time; next in order.	after that time
Example	I finished my homework, and then I went outside to play.	She married at 17 and gave birth to her first child shortly thereafter.
Register	Neutral	Formal
How common	Top 1,000 (very common)	Beyond 10,000 (less common)
CEFR level	A1	C1
Part of speech	adverb	adverb
Collocations	then and there, back then, if... then, then again, more then	thereafter stated, thereafter mentioned, thereafter noted
Antonyms	before, previously	before, prior to, previously
Common mistakes	Confused with 'than' when comparing things., Used incorrectly at the beginning of a sentence without a connecting clause., Mixing 'then' with 'than' in conversations.	Using it incorrectly to indicate a specific time instead of a sequence., Confusing it with 'after' or 'then' in casual contexts., Placing it incorrectly in a sentence, disrupting the flow.
Usage notes	Used to indicate a time in the past or future. Often used in storytelling. Avoid using in formal writing; instead, use 'subsequently' or 'afterward'.	Used primarily in writing, particularly in formal contexts such as academic papers or literature. It is less common in everyday spoken language. Avoid using it in casual conversations.

Frequently asked questions: Then vs Thereafter

What's the difference between Then and Thereafter?

Then: At that time; next in order. Thereafter: after that time

Which is more formal: Then and Thereafter?

Thereafter is the most formal of these.

Which is more common: Then and Thereafter?

Then is the most common in everyday English.

Are Then and Thereafter the same CEFR level?

Then: A1, Thereafter: C1 on the CEFR scale.

Can I use Then and Thereafter interchangeably?

Not always. Then and Thereafter 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.