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
Use a plain, light background (white, light gray or cream) that contrasts with your face.
Your head, shoulders and upper body must be visible, with no other people or objects.
Don't upload a photo of your passport or a photo of a photo: it must be new and unfiltered.
How to do it with Requisito Listo
Open the «UK visa photo» template in the app.
Take the photo with the on-screen guide (or pick one from your gallery).
The app centers your face, makes the background white and gets the exact size and file weight.
Check the checklist, then 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.