Additionally vs I'll tell you what else

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

Additionally

FormalTop 2,000 (common)B2adverb

I'll tell you what else

InformalTop 5,000 (fairly common)
Most formal: AdditionallyMost common: Additionally
 AdditionallyI'll tell you what else
Pronunciation🇬🇧 /["/əˈdɪʃənəli/"]/🇺🇸 /["/əˈdɪʃənəli/"]/🇬🇧 //aɪl tɛl jʊ wɒt ɛls//🇺🇸 //aɪl tɛl jʊ wʌt ɛls//
Meaningalso; in additionI will share more information.
ExampleAdditionally, the bus service will run on Sundays, every two hours.I'll tell you what else I found during my research.
RegisterFormalInformal
How commonTop 2,000 (common)Top 5,000 (fairly common)
CEFR levelB2-
Part of speechadverb
Collocationsadditionally, we should consider, additionally, the study found, additionally, there is evidencetell you what else happened, tell you what else to consider, tell you what else we need
Antonymsonly, exclusively, solely-
Common mistakesUsing 'additionally' to start a sentence in too informal a context., Confusing with 'also' in terms of formality., Overusing in casual writing; it sounds too formal.Used too formally in business contexts., Confused with similar phrases like 'Additionally' or 'Moreover'.
Usage notesUsed to introduce more information or to add another point, primarily in formal writing or presentations. Not common in casual conversations.This phrase is often used in conversations to introduce an additional point or idea, making it suitable for casual settings. It may not be appropriate in formal written communication.

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I'll tell you what else

Frequently asked questions: Additionally vs I'll tell you what else

What's the difference between Additionally and I'll tell you what else?

Additionally: also; in addition I'll tell you what else: I will share more information.

Which is more formal: Additionally and I'll tell you what else?

Additionally is the most formal of these.

Which is more common: Additionally and I'll tell you what else?

Additionally is the most common in everyday English.

Can you show an example of each?

Additionally: Additionally, the bus service will run on Sundays, every two hours. I'll tell you what else: I'll tell you what else I found during my research.

Can I use Additionally and I'll tell you what else interchangeably?

Not always. Additionally and I'll tell you what else 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.