Frequently used before nouns like damage, cost, amount, effort, and care. Unlike 'minimum', which is usually a noun or determiner, 'minimal' works as a standalone adjective in both attributive and predicative positions.
常見錯誤
We need to keep costs to a minimal.
We need to keep costs to a minimum.
'Minimum' is the noun form; 'minimal' is an adjective and cannot follow 'a/an' alone.
He received only minimal injuries in the accident.' (when meaning not serious).
He received only minor injuries in the accident.
'Minimal' means 'the smallest possible', while 'minor' means 'not serious in importance'.