TL;DR
UKVCAS biometrics in the UK enforce a 6 MB per-file upload limit. Most visa bundles hit this comfortably with our free browser-based compressor's structural-only pass — no quality loss. If yours is genuinely huge, the re-rendering fallback gets there too. Nothing uploaded, nothing logged.
How to compress a PDF to 6 MB
- Open the Compressor — go to findmyvisa.co.uk/compress.
- Drop your PDF in — single file, up to 100 MB. Read into browser memory only.
- Pick "6 MB" — radio button labelled "6 MB · UKVCAS". This is the right target for in-country biometrics.
- Click "Compress to 6 MB" — structural pass runs first; if your bundle is already efficient, this is enough.
- Download and upload — save and upload through UKVCAS as instructed.
When 6 MB is enough
A typical Skilled Worker or Student visa bundle:
| Bundle contents | Typical raw size | After our structural pass |
|---|---|---|
| Skilled Worker (no photos) | 2-5 MB | 1.5-4 MB |
| Spouse / Family (with photos) | 5-12 MB | 4-8 MB |
| ILR (5 years of evidence) | 8-20 MB | 6-15 MB |
| Student (CAS + financial + qualifications) | 2-4 MB | 1.5-3 MB |
| Visitor | 1-3 MB | 0.8-2 MB |
For most bundles, 6 MB is comfortable. The structural pass alone usually gets you there without any visual change.
When the re-render kicks in
If your bundle is over 6 MB after the structural pass, re-rendering starts. We try DPI/quality combinations in this order:
| DPI | JPEG quality | When this is enough |
|---|---|---|
| 200 | 85% | Most bundles 6-15 MB |
| 170 | 78% | Bundles with some photo evidence |
| 144 | 72% | Photo-heavy bundles |
| 120 | 65% | Very photo-heavy bundles |
| 96 | 60% | Last resort for legible text |
Below 96 DPI we warn that text may be hard to read; we keep going to 64 DPI as the absolute minimum if asked.
Tips for staying under 6 MB
Use the bundler's built-in size check
Our Bundler shows the result file size in the success panel — if it's already over 6 MB it suggests running through the compressor.
Trim duplicate evidence
Many applicants bundle:
- Multiple copies of the same passport scan
- Whole bank statement bundles for periods UKVI didn't ask about
- Family / friend reference letters that aren't required for the route
- High-res photos when 200 KB would suffice
Reduce these and the compression task gets easier.
Greyscale documents
Bank statements, employer letters and contracts compress to a fraction of their colour size when greyscale. Most scanners have a greyscale mode. UKVI accepts greyscale for non-photo documents.
Re-scan oversized documents
A passport bio page scanned at 1200 DPI is 8-15 MB on its own. Rescan at 300 DPI — perfectly legible, 1-2 MB, no compression needed.
Common issues
Bundle uploads but caseworker can't read it
This happens when re-rendering pushed DPI very low. Check the result PDF on a desktop screen at 100% zoom — if text is fuzzy, re-bundle with smaller source files instead of relying on aggressive compression.
Multi-part visa applications
Some applications upload several files separately (passport, financial, accommodation as 3 different PDFs). Each file gets the 6 MB cap individually — you don't need to compress everything into one 6 MB bundle. Use our Bundler to merge per category, then compress each category to its own 6 MB or below.
File "uploads" but doesn't attach
UKVCAS sometimes shows the file as uploaded but it doesn't actually attach. Refresh the page after upload to confirm; if the file is missing, re-upload (likely a too-large file silently rejected).
Tools mentioned
- Compress PDF for UK visa — the compressor
- Visa Document Bundler — bundle in canonical order before compressing
- Personalised checklist — confirm what to include
Sources
Common questions
- 01
Why is the UKVCAS limit 6 MB?
UKVCAS, run by Sopra Steria for in-country UK biometrics, caps each file at 6 MB. The limit is enforced silently — files over 6 MB fail to attach with no error message, leaving applicants thinking they uploaded successfully when they didn't.
- 02
Will compressing to 6 MB lose quality?
Most bundles reach 6 MB with structural optimisation alone — zero quality loss. Re-rendering only kicks in if needed. The 6 MB target is generous enough that text usually stays selectable and images stay clear.
- 03
What if my bundle is genuinely over 50 MB?
Bundles that large usually contain duplicate evidence, oversized scans, or content UKVI didn't ask for. Trim the bundle first, then compress. The compressor's max input is 100 MB but the practical sweet spot is 5-30 MB raw.
Free tools that pair with this guide