A4, A3, Letter and Legal PDF Page Sizes Explained
Compare common paper dimensions and learn when to resize, fit or add margins.
Paper names are regional conventions. Choosing the wrong one can create unexpected scaling, blank bands or clipped edges when printing or submitting forms.
PDF uses points internally, but tools often ask for millimetres or a named preset.
Common dimensions
A4 measures 210 × 297 mm. A3 is twice the area of A4 at 297 × 420 mm. US Letter is 8.5 × 11 inches, and US Legal is 8.5 × 14 inches.
A4 and Letter are close but not identical. Automatic printing can scale one to the other.
Orientation changes width and height
Portrait uses the shorter edge as width; landscape swaps the orientation. Choose based on content, not only the source page.
Wide spreadsheets and diagrams may need landscape to keep text readable.
Fit, fill and margins
Fit preserves all source content and may create white space. Fill covers the target but can crop. A small margin protects printer non-printable areas and content near edges.
For official forms, preserving every field is more important than removing white borders.
Mixed-page documents
A PDF can contain multiple page sizes. Standardizing them improves printing consistency, but scaling can make some pages smaller.
Review every page after conversion, especially folds, attachments and landscape pages.
Common page dimensions
| Preset | Dimensions | Typical use |
|---|---|---|
| A4 | 210 × 297 mm | International office/forms |
| A3 | 297 × 420 mm | Posters, plans, large tables |
| Letter | 8.5 × 11 in | US/Canada office |
| Legal | 8.5 × 14 in | Specific legal/administrative forms |
Final checklist
Confirm recipient region and requirement
Choose orientation
Use Fit for documents
Add a safety margin
Print-preview the result
Questions people ask
Is A4 the same as Letter?
No. They have different proportions.
Can one PDF contain A4 and Letter pages?
Yes, but printing may scale pages differently.
Does changing page size reduce MB?
Not automatically.
This article explains the current DocPixel interface and known trade-offs. Requirements from a receiving institution or software provider take priority.