Guides & tips for working with PDFs
Practical how-tos, behind-the-scenes notes, and product updates from the team behind Blackpdf.
Edit & Organize
Compress, merge, split, rotate, resize, and flatten pages.
How to Fix a PDF Form That Won't Print or Display Right
Filled-in form fields that vanish when printed, or look wrong on someone else's screen? Flattening merges them into the page so everyone sees exactly what you see.
How to Merge PDFs in the Right Order
Merged files coming out jumbled? Here's why upload order isn't what you think, how to control the sequence, and the filename trick that makes it automatic.
How to Resize a PDF to A4 (or Letter)
Convert a PDF to A4 or US Letter so it prints and uploads correctly. Why the two sizes aren't interchangeable, and how to force every page to the one you need.
How to Make All PDF Pages the Same Size
One odd page in an otherwise uniform document? Here's how to detect the outliers and normalize just those — without touching the pages that were already correct.
How to Rotate a PDF Without Breaking Your Page Sizes
Rotating a page 90° turns it landscape — which leaves your document with mismatched page widths. Here's what the Maintain page width option does and when you need it.
How to Remove a Page from a PDF
Need to take one page — or a few — out of a PDF? Here's how to remove pages, and when deleting is the wrong move and you should extract the pages you want instead.
How to Fix a Sideways or Upside-Down PDF (Permanently)
Your PDF opens sideways and your reader's rotate button doesn't save it. Here's how to fix the orientation permanently — one page, all pages, or an upside-down scan.
How to Delete Blank Pages from a PDF
Scanners love adding blank pages. Here's how to find and remove them, why a 'blank' page often isn't truly blank, and how to spot the ones that only look empty.
Why Won't My PDF Compress? (And What to Do Instead)
Compressed your PDF and it barely shrank? Here's why some PDFs resist compression, how to diagnose what's actually making yours big, and the fixes that work when compression doesn't.
How to Compress a Scanned PDF (Without Making It Unreadable)
Scanned PDFs are huge because every page is an image. Here's how to shrink one properly — grayscale first, compress second, OCR in the right order — and keep the text legible.
How to Compress a PDF for Email (Attachment Too Large)
Your email bounced because the PDF attachment is too big. Here's how to get under Gmail and Outlook's limits, why the cap is smaller than you think, and when to send a link instead.
How to Split a PDF Into Multiple Files at Once (with Groups)
Split one PDF into several documents in a single pass using color-coded groups. Assign pages to groups, name each one, and export one PDF per group — step by step.
How to Compress a PDF to 5 MB (for Email)
Email bouncing because your PDF is over the 5 MB limit? Here's how to get a PDF under 5 MB while keeping it looking good — usually with the lightest compression.
How to Compress a PDF to 500 KB
Need a PDF under 500 KB for an upload or email? Here's how to hit that target, the quality you can expect at 500 KB, and what to do if it overshoots.
How to Compress a PDF to 1 MB
Need a PDF under 1 MB for email or an upload? Here's how to hit 1 MB while keeping the document looking good, and what to do if it lands over.
How to Compress a PDF to 100 KB
Need a PDF under 100 KB for a form or upload with a tight size cap? Here's how to hit that target, what quality to expect at 100 KB, and what to do when the file won't go that low.
How-ToHow to Flatten a PDF (And When You Actually Need To)
Flatten a PDF to bake annotations, form fields, signatures, and layers into the page. Step-by-step guide, plus when flattening is required and when it isn't.
How-ToHow to Rotate a PDF (Fix Sideways Pages)
Rotate pages in a PDF document: all pages at once, just the sideways ones, or one page at a time. Step-by-step guide with the permanent-rotation gotcha.
How-ToHow to Resize PDF Pages to a Uniform Size
Fix a PDF with uneven page sizes. Resize pages to A4, Letter, Legal, or a custom size, choose how content scales, and normalize only the outliers.
Why a PDF's Pages End Up Different Sizes (and How Page Boxes Work)
A PDF stores a size on every page, not one for the whole file. Here's why pages drift apart, what MediaBox and CropBox actually do, and how to make them match.
How-ToHow to Delete Pages from a PDF
Remove blank pages, covers, or anything else you don't want from a PDF. Step-by-step guide with bulk selection and tips for large documents.
How-ToHow to Merge PDFs Into One File
How to merge PDFs into a single document: drag, reorder, combine. Includes page-level merging and what to do for password-protected or large files.
How-ToHow to Split a PDF Into Multiple Files
Step-by-step guide to splitting a PDF online: by page range or into individual pages. Free, no installation required.
How-ToHow to Compress a PDF Without Losing Quality
Compress a PDF online without losing quality. Step-by-step guide to preset levels, custom target file sizes, and flatten-then-compress for stubborn files.