Drop your photo, get a JPEG inside the UKVI digital photo file rules for ETA and visa applications — at least 50 KB, at most 6 MB. Nothing is uploaded; it all runs in your browser.
UK Visas and Immigration publishes one set of formatting rules for the face photo on an ETA (Electronic Travel Authorisation) and on visa applications generally — the guidance page “Take a photo of your face for a visa application or permission” is exactly what gov.uk's ETA apply page links as the rules for digital photos of faces. The photo must be a jpg or jpeg file, at least 600 pixels wide and 750 pixels tall, at least 50 KB and no more than 6 MB, vertically orientated and not mirrored or flipped; clear, in focus, in colour, taken in a well-lit room, and not altered by computer software. This page is preset to the 50 KB–6 MB window with no pixel size set, which is deliberate: 600×750 is a floor, not a target, and cropping resolution away helps nobody. A normal phone photo passes the pixel floor easily.
If you apply through the UK ETA app, it uses your phone camera live — you never touch a file, and nothing on this page applies. The file rules matter on the online route (used when you can't run the app, or when applying for someone who isn't with you) and on visa forms that take an uploaded photo: visit, work, study and family applications. If your photo doesn't meet the rules, UKVI says the application may be delayed or rejected.
The photo must not be a scan or photo of another photo of you, and it must not be the same photo that's in your passport — re-photographing the passport's own picture fails both at once, and it's a common shortcut. Take a fresh one: phone or tablet is explicitly fine, and UKVI recommends having someone else take it rather than a selfie. “Not altered by computer software” is about your appearance — no filters, no retouching, no AI cleanup. It doesn't prohibit the byte plumbing every digital photo goes through; PixFit re-encodes at the best quality that fits the size window and changes nothing about how you look.
Files land under 50 KB for one usual reason: a messaging app recompressed them. PixFit can pad a JPEG up to the 50 KB floor with a spec-valid comment segment, but padding adds no detail, and a message-app copy is often also soft or below 600×750 — which PixFit won't upscale, because resampling can't invent the resolution UKVI checks for. The honest fix is the original file (ask the sender to resend as a document / “actual size”) or a new photo. Files over 6 MB — large phone photos, high-res scans — drop straight in and come out at best quality under the cap, full resolution kept. An iPhone HEIC can be dropped directly too: PixFit decodes it in your browser and outputs the jpg the rules require, stripping EXIF metadata (including GPS) in the re-encode.
Everything else on UKVI's list is composition, and no resizer can judge it: plain light-coloured background with clear contrast, no other people or objects, head, shoulders and upper body in frame, facing straight at the camera, plain expression with mouth closed, eyes open and visible with no hair across them, no shadows on your face or behind you, no red-eye, no head covering except for religious or medical reasons, and glasses only if you must wear them (no tint, no glare over the eyes). Babies and children have relaxed rules — under-6s needn't look at the camera, under-1s needn't have eyes open. Check the current list at gov.uk before you submit.
A UK passport application uses a different digital photo spec — same 600×750 and 50 KB floors, but a 10 MB cap and its own rules (HMPO crops the photo for you; it must be under a month old) — see the UK passport photo page. The ETA online route also wants a photo of your passport's information page; that's a document photo with no published file numbers — follow the form's own prompts there. Applying elsewhere? See the US visa, NZeTA / NZ visa and South Korea K-ETA pages.