Complementary vs. Complimentary
“Complementary” and “complimentary” sound alike but have different meanings. “Complementary” describes things that complete or work well with each other, while “complimentary” can mean praising or given free of charge.
Use “complementary” when two things work well together; use “complimentary” for praise or something provided free.
Key details
Choose the right form
| Meaning / situation | Form / construction | Decision |
|---|---|---|
| two things complete or work well with each other | complementary | Use the form related to complement. |
| praising or approving | complimentary | Use the form related to compliment. |
| provided free of charge | complimentary | Use the documented free-of-charge sense. |
Quick tests
Meaning / construction test
Does the adjective mean that two things complete or suit one another?
If yes: Use “complementary.”
If no: Use “complimentary” for praise or for something provided free of charge.
Caveat: Choose by the documented meaning or construction; a different pattern may be valid in a different sentence structure.
Examples
The two research methods are complementary.
They work together rather than duplicate the same role.
The reviewer was complimentary about the revised draft.
The adjective describes praise.
Guests received complimentary coffee.
The adjective means provided without charge.
Further guidance
Core difference
Use “complementary” for things that fit together or complete one another. Use “complimentary” for praise or for something given free of charge.
Fast Test
Think “complement” for completion and “compliment” for praise. If a hotel gives you a free breakfast, it is complimentary.
Meaning Boundary
“Complimentary” has two common senses—praising and free—so context determines which one is intended.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- Complementary — English meaning (opens in a new tab)Cambridge University Press · Dictionary meaning of complementary as working well together or completing another thing
- Complimentary — English meaning (opens in a new tab)Cambridge University Press · Dictionary meanings of complimentary as praising or provided free of charge