UK Visas and Immigration (UKVI) applications require a substantial set of supporting documents. Whether you are applying for a spouse visa, a Skilled Worker visa, a Student visa, or indefinite leave to remain, the document portal typically restricts uploads to 6MB per file. Passport biographical pages, bank statements, accommodation letters, employment contracts, and payslips all need to be in PDF format and under that limit.
For many applicants, bank statements and scanned correspondence are routinely over 6MB. Here is a complete, reliable workflow for compressing visa documents without losing the details that caseworkers examine.
What UKVI checks in your uploaded documents
This context matters for compression. UKVI caseworkers and Entry Clearance Officers examine specific details in each document type:
- Passport, MRZ (machine readable zone) at the bottom of the biodata page, photograph clarity, full name, date of birth, nationality, expiry date
- Bank statements, account holder name, account number and sort code, statement period (must be consecutive months), opening and closing balances, individual transaction figures
- Payslips, employer name, employee name, NI number, gross pay, deductions, net pay, payment date
- Employer letter / HR letter, employer name, address, employee name, job title, salary, employment start date, signature
- Accommodation evidence, full address, lease term, signatures, reference numbers
Every one of these details needs to be clearly readable after compression. For visa applications, the rule is: compress only as much as needed to clear the 6MB limit, and always verify the critical details before uploading.
The recommended compression target: 5MB
UKVI's stated limit is 6MB, but compressing to 5MB gives you a meaningful safety margin. Some browsers or upload systems calculate file sizes differently (MB vs MiB), and a file that is technically 5.9MB may fail in practice on certain portal implementations. A 5MB target avoids the boundary entirely.
Document-by-document compression guide
Passport scan PDF
The biodata page photographed or scanned from a modern passport (post-2015 UK biometric passports) is typically a HEIC or JPEG image. If you are submitting a photo as a PDF, convert it first using a browser-based tool, then compress if needed. The passport biodata page as a standalone PDF should be under 2MB at a quality level that keeps the MRZ and photograph clear.
If your PDF contains multiple passport pages (plus the visa stamp pages or BRP), the file will be larger. Target 5MB and check that the MRZ text, the two rows of machine-readable characters, is sharp enough to read at full zoom.
Bank statements
Bank statements for visa applications typically need to cover the past 6 months (for most visa categories) or the past 28 days (for Standard Visitor visas in some cases, check the guidance for your specific visa type).
Online banking PDFs from UK banks range from 3MB (simple current accounts with few transactions) to 20MB+ (business accounts with hundreds of transactions per month). Compress to 5MB. If quality is insufficient at 5MB, delete pages you genuinely do not need first, for example, supplementary pages that only contain privacy notices or marketing, not transaction data.
Employment documents and payslips
Digital payslips from payroll portals are usually already under 1MB. Printed-and-scanned payslips may be 2–5MB per page. Compress to under 5MB and check the NI number, employer PAYE reference, and all pay figures.
Employer letters should be on company letterhead with a physical signature. If yours is a scanned colour document, expect 2–6MB. Target 3MB for letters, there is usually less image data than in a bank statement, and quality holds well at that target.
Accommodation evidence (tenancy agreement, letter from host)
Tenancy agreements as PDFs are often large (10–40MB) because they contain many pages of standard contract terms plus scanned signatures. For visa purposes, you usually only need specific pages: the first page (parties, property address, term), the rent page, and the signed/dated page. Delete the standard terms pages before compressing, this reduces a 30-page agreement to 5–8 pages, which compresses comfortably to under 5MB.
Compressing on your phone during the application
Many visa applicants manage documents entirely from their phones. PDFWhisk works in Safari on iPhone and Chrome on Android. Open the compress tool, load the PDF from the Files app or cloud storage, set 5MB, and download the result. The process is identical to desktop, nothing is uploaded to any server.
For large files (over 30MB) on older phones, the compression may take 15–30 seconds. Keep the browser tab in the foreground during processing to prevent the phone from pausing the JavaScript.
Privacy: why local processing matters for visa documents
Visa applications involve some of the most sensitive personal documents imaginable: passports, financial records, employment history, and personal correspondence. Uploading these to a generic online compressor means those documents pass through an external server, with whatever data practices that service has.
PDFWhisk's compression runs entirely in your browser. The file is processed locally using JavaScript on your device. Nothing is sent to any server. Your passport scan, NI number, and financial records stay on your device throughout the workflow. See the Privacy Proof page for the technical details.
Before you upload to UKVI: final checklist
Before uploading any compressed PDF to the visa portal:
- Zoom to 150% on each critical detail (MRZ on passport, account numbers on statements, NI number on payslips)
- Check that dates are readable, statement period, employment dates, document issue and expiry dates
- Confirm the file is under 6MB (ideally under 5MB)
- Keep the uncompressed originals until your visa decision is issued
- Name each file clearly before uploading, caseworkers see the filename and it can affect how documents are matched to requirements
A well-prepared document set that is clearly readable is a meaningful advantage in any visa application. Compression is a small but important part of making the submission as smooth as possible.