Compress a PDF to Send on WhatsApp
On WhatsApp, a single document caps out at about 100MB, but a large file also takes time to upload and a recipient on mobile data may not want a 40MB PDF. Compress PDF may reduce transfer time and data use, but cannot guarantee a successful send. Processing is local, with nothing uploaded. Below: WhatsApp's send limits and how to compress.
What are WhatsApp's limits for sending a PDF?
WhatsApp caps the size of a file sent as a document, and going over means it won't send; even under the cap, a large file slows your upload and the recipient's download.
- Sent as a document: roughly 100MB per file; over that it won't send.
- Upload / download speed: a tens-of-MB PDF is slow and data-hungry on mobile, so smaller is a better experience.
- Groups: the bigger the file, the more storage and data it costs every member — smaller is more considerate.
How do you shrink a PDF so it sends on WhatsApp?
Compressing on a computer and then sending works well, and so does opening compress cat in your phone's browser. Scans and photo PDFs compress best.
- Open Compress PDF and drag in the file you want to send.
- For a lighter transfer, try a target such as 5120 KiB or 10240 KiB, then check the displayed bytes against the receiving limit.
- Review the file's method, then click 'Compress files'. 'Keep selectable text' is the default; 'Compress as images' removes selectable text and may soften details. Check output bytes and all pages.
- Download, then send it on WhatsApp as a 'document'.
Will compression hurt the quality?
Contracts, receipts and document scans may shrink with image compression, but fine details can be lost. Start with 'Keep selectable text' and inspect every page if you explicitly choose 'Compress as images'.
- Scans / photo PDFs: image compression may save space, but check small print and any existing OCR layer.
- Pure-text documents: start with 'Keep selectable text'; an already small PDF may not need compression.
- Good enough beats tiny: the recipient just needs to read it, so 10MB is often safer than 2MB.
- Zoom in to check text and stamps after compressing, then send.
Frequently asked questions
WhatsApp says my PDF is too large — what do I do?
Try reducing it below the ~100MB document limit, then check output size before sending. For a faster transfer, request a smaller target like 5MB or 10MB, but reaching the target and a successful send are not guaranteed. Processing is local, with nothing uploaded.
Can I compress a PDF on my phone before sending it on WhatsApp?
Yes. Open compress cat's Compress PDF in your phone browser, pick the file and a target, compress, download, then send it on WhatsApp as a document.
Will compression make it unreadable for the recipient?
It can if you choose 'Compress as images', which may soften small print and other details. Start with 'Keep selectable text', review output bytes, and inspect every page. A target is best effort, not a readability guarantee.
Is it safe to process the file in compress cat?
Yes. Compression runs entirely in your browser via WebAssembly, so the PDF is never uploaded and stays on your own device.
Updated · compress cat team