Bug vs Mistake

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

Bug

Top 1,000 (very common) B2 noun

Mistake

Top 1,000 (very common) A1 noun

	Bug	Mistake
Pronunciation	🇬🇧 /["/bʌɡ/"]/ 🇺🇸 /["/bʌɡ/"]/	🇬🇧 /["/mɪˈsteɪk/"]/ 🇺🇸 /["/mɪˈsteɪk/"]/
Meaning	A small insect or mistake in a program.	An error or something done wrongly.
Example	There's a bug crawling up your arm.	I made a mistake on my homework.
Register	Neutral	Neutral
How common	Top 1,000 (very common)	Top 1,000 (very common)
CEFR level	B2	A1
Part of speech	noun	noun
Collocations	nasty, flu, stomach, have, catch, come down with, go around, go round, strike somebody down, with a/​the bug, be bitten by, catch, get, bite (somebody), minor, annoying, computer, discover, find, fix, bug in	big, colossal, great, make, commit, repeat, happen, occur, by mistake, mistake about, all a mistake, an easy mistake to make, make the mistake of doing something, big, colossal, great, make, commit, repeat, happen, occur, by mistake, mistake about, all a mistake, an easy mistake to make, make the mistake of doing something
Antonyms	feature, blessing	correct, success
Common mistakes	Confused with 'bugged' as a past verb., Omitting 'a' when referring to an insect (e.g., saying 'I saw bug')., Using 'bug' in a formal report instead of more technical terms.	'Mistakes' as a singular instead of plural (e.g., saying 'a mistake' when referring to multiple errors)., Confusing 'mistake' with 'error', where 'mistake' is more general., Using 'mistake' without a clear object (e.g., saying 'I made a mistake' is fine, but 'I made' alone is unclear).
Usage notes	Use 'bug' for insects in everyday conversation. In tech, 'bug' refers to errors in software. Avoid using in very formal contexts.	Used in both casual and formal contexts. It’s appropriate in everyday conversation but can also be used in professional discussions about errors.

See it in real clips

Sherlock › S1 E1

Wouldn't have taken him more than five minutes to realise his mistake.

Agatha Christies Poirot › S1 E1

if there's some mistake.

Sherlock › S1 E1

Wouldn't have taken him more than five minutes to realise his mistake.

Agatha Christies Poirot › S1 E1

if there's some mistake.

Mistake

Frequently asked questions: Bug vs Mistake

What's the difference between Bug and Mistake?

Bug: A small insect or mistake in a program. Mistake: An error or something done wrongly.

Which is more advanced: Bug and Mistake?

Bug is the highest level, at B2, on the CEFR scale.

Are Bug and Mistake the same CEFR level?

Bug: B2, Mistake: A1 on the CEFR scale.

What part of speech are Bug and Mistake?

Bug: noun, Mistake: noun.

Can you show an example of each?

Bug: There's a bug crawling up your arm. Mistake: I made a mistake on my homework.

Can I use Bug and Mistake interchangeably?

Not always. Bug and Mistake 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.