This is the commonly used size: we found no requirement published by the institution. Confirm it before your application.
Tips to get it right the first time
Scan each certificate and transcript in full, including any translations.
Keep the original documents: you may be asked for them.
No size limit is published here: if the portal rejects a file, use "Reduce PDF or photo size".
How to do it with Requisito Listo
Open «UK ENIC: qualification documents».
Add the PDFs and photos in the order requested.
The app joins them into one A4 PDF under the maximum size.
Upload or save it.
At the end you'll see a checklist: size, file weight, background and format. If something doesn't comply, it tells you what to fix before the portal rejects it.