PDF guides & how-tos
Learn how PDF compression actually works, then jump to the exact scenario you're facing — exams, visas, government portals, email, WeChat, WhatsApp, scans and job applications. Every tool runs locally in your browser; your files are never uploaded.
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The Complete Guide to PDF Compression
How PDF compression works, lossy vs. lossless, how to compress a PDF to an exact size like 100KB / 200KB / 1MB, and what to do when a file won't get small enough.
PDF Compression Methodology
Where a PDF's size actually comes from, what compression really does, how much each technique (down-sampling, JPEG quantization, grayscale, de-duplication) saves, and a decision tree for picking the right method. With a compression-ratio reference table by content type.
By scenario9
Compress a PDF for Exam Registration
Exam and test-registration portals often cap uploads at ≤200KB (sometimes ≤50KB for the photo). This guide shows how to hit the limit while keeping your documents sharp.
Compress Visa Documents to Under 1MB
Consulate portals and visa centers often require each PDF to be ≤1MB. This guide shows how to batch-compress visa documents under the limit while keeping scans readable.
Compress PDFs for Government Portals
Government and agency portals often require licenses and contract scans to be ≤500KB or they can't be submitted. This guide shows how to hit the limit and pass in one go.
Compress a PDF to Send It as an Email Attachment
Gmail caps attachments at 25MB and Outlook at ~20MB, so a big PDF bounces or turns into a link. Here are the real limits and how to shrink a PDF enough to send.
Compress a PDF to Send on WeChat
WeChat caps the documents you send in chat, and big PDFs are slow to upload and eat the recipient's data. Here's how to shrink a PDF so it sends smoothly.
Why Scanned PDFs Are So Big — and How to Compress Them
A scanned PDF can be tens of megabytes because every page is a high-resolution image. Here's why scans are huge and how to shrink them to a target size while staying legible.
Compress a Résumé or Portfolio PDF for Job Applications
Job portals and ATS systems often cap résumé and portfolio uploads (e.g. ≤2MB or ≤10MB). Here's how to get your application under the limit without blurring it.
Compress a PDF to Send on WhatsApp
WhatsApp caps a document at about 100MB, and big files are slow to upload and heavy on the recipient's data. Here's how to shrink a PDF so it sends fast and stays clear.
The Complete Upload Size-Limit Table
One place to look up the PDF/image upload size caps for visa centers, government portals, email providers and social platforms — in KB/MB — plus what target to compress to so you don't get rejected. A regularly reviewed facts table.