"I'm wearing school uniform."

Translation: Dw i'n gwisgo dillad ysgol.

[estronwen]

Does this translate as school clothes? For uniform should the phrase 'gwisg swyddogol' be used?

[EllisVaughan]

"Dillad ysgol" best translates as "School clothes". "Gwisg ysgol" is "Uniform". "Gwisg swyddogol" would be "Official uniform".