Paper Size Converter
10 formats
International StandardsConvert between paper size standards including A4, Letter, Legal, and international formats. Get precise dimensions in millimeters, inches, and centimeters.
Select Paper Size
Choose from international paper size standards
Categories
A0
841 × 1189 mm
ISO A
A1
594 × 841 mm
ISO A
A2
420 × 594 mm
ISO A
A3
297 × 420 mm
ISO A
A4
210 × 297 mm
ISO A
A5
148 × 210 mm
ISO A
Letter
216 × 279 mm
ANSI
Legal
216 × 356 mm
ANSI
Tabloid
279 × 432 mm
ANSI
Executive
184 × 267 mm
ANSI
A4
Most common paper size worldwide
ISO A
Dimensions
Millimeters (mm)
210 × 297
Inches (in)
8.27" × 11.69"
Centimeters (cm)
21.0 × 29.7
Area
0.62 m²
Usage Information
Common Use: Letters, documents, magazines
Series: A Series
Standard: ISO 216 (International)
Quick Size Comparison
Compare A4 with other common paper sizes
A3
297 × 420 mm
A4
210 × 297 mm
Letter
216 × 279 mm
Legal
216 × 356 mm
Complete Paper Size Conversion Guide
Master paper size conversions with our comprehensive guide
Converting Between ISO and ANSI Standards
ISO A Series to ANSI
A4 (210 × 297 mm) ≈ Letter (8.5" × 11")
A4 is slightly narrower and taller than Letter. Content may need margin adjustments.
A3 (297 × 420 mm) ≈ Tabloid (11" × 17")
A3 is slightly smaller than Tabloid. Scale factor: approximately 0.97x.
A5 (148 × 210 mm) ≈ Half Letter (5.5" × 8.5")
A5 is wider but shorter than Half Letter. Consider orientation when converting.
ANSI to ISO A Series
Letter (8.5" × 11") ≈ A4 (210 × 297 mm)
Letter is wider and shorter than A4. May require content repositioning.
Legal (8.5" × 14") ≈ A4+ (custom)
Legal has no direct ISO equivalent. Use A4 with extended length or A3 folded.
Tabloid (11" × 17") ≈ A3 (297 × 420 mm)
Tabloid is larger than A3. Scale content to 103% when converting to A3.
Metric to Imperial Paper Dimension Conversions
Conversion Formulas
mm to inches:
inches = mm ÷ 25.4
inches to mm:
mm = inches × 25.4
cm to inches:
inches = cm ÷ 2.54
Common Conversions
210 mm8.27 inches
297 mm11.69 inches
216 mm8.50 inches
279 mm11.00 inches
Precision Tips
Rounding: Round to 2 decimal places for printing accuracy.
Tolerance: Allow ±0.5mm tolerance for commercial printing.
Bleed: Add 3mm (0.12") bleed for professional printing.
Understanding Aspect Ratios and Scale Relationships
ISO A Series Aspect Ratio
√2 : 1 (1.414 : 1)
The ISO A series maintains a consistent √2:1 aspect ratio across all sizes.
Benefit: When folded in half, the aspect ratio remains the same.
Example: A4 folded becomes A5 with identical proportions.
Scale Relationships:
A0 → A1: 70.7% scale
A1 → A2: 70.7% scale
A2 → A3: 70.7% scale
A3 → A4: 70.7% scale
ANSI Series Aspect Ratios
Letter: 1.294 : 1
8.5" × 11" = 1.294 aspect ratio
Legal: 1.647 : 1
8.5" × 14" = 1.647 aspect ratio
Tabloid: 1.545 : 1
11" × 17" = 1.545 aspect ratio
Note: ANSI sizes don't maintain consistent aspect ratios when scaled.
Professional Applications & Industry Standards
Paper size requirements across different industries and regions
Business Document Standards by Country
United States & Canada
Business Letters
Letter (8.5" × 11") - Standard
Legal Documents
Legal (8.5" × 14") - Required
Executive Reports
Executive (7.25" × 10.5") - Premium
Europe & International
Business Correspondence
A4 (210 × 297 mm) - Standard
Technical Documents
A3 (297 × 420 mm) - Drawings
Brochures
A5 (148 × 210 mm) - Marketing
Asia Pacific
Japan (JIS B Series)
B4, B5 - Traditional formats
China & India
A4 - International standard
Australia
A4 - Government & business
Legal Document Requirements
US Legal System
Court Documents
Federal Courts: Legal size (8.5" × 14") required
State Courts: Varies by jurisdiction
Pleadings: Legal size with specific margins
Contracts & Agreements
Standard: Letter size acceptable
Complex: Legal size for lengthy documents
Signatures: Minimum 1" margin at bottom
International Legal
European Union
Official Documents: A4 standard
Treaties: A4 with specific formatting
Court Filings: A4 with country variations
International Trade
Contracts: A4 preferred globally
Shipping Docs: A4 for customs forms
Certificates: A4 for ISO compliance
International Correspondence Guidelines
Best Practices
Global Standard
Use A4 for international business correspondence
US Recipients
Consider Letter size for US-based partners
Digital First
PDF format eliminates paper size concerns
Envelope Compatibility
A4 folded onceC5 envelope (162×229mm)
A4 folded twiceC6 envelope (114×162mm)
Letter folded once#10 envelope (4.125"×9.5")
Letter unfolded9"×12" envelope
Printing Industry Standards and Bleeds
Bleed Requirements
Standard Bleed
3mm (0.125") on all sides
Large Format
6mm (0.25") for posters
Book Printing
3-5mm depending on binding
Safety Margins
Text Safety
6mm (0.25") from trim edge
Logo Placement
10mm (0.4") minimum margin
Binding Edge
15mm (0.6") for perfect binding
Print Tolerances
Cutting Tolerance
±0.5mm for commercial printing
Registration
±0.1mm for high-quality work
Folding Accuracy
±1mm for machine folding
Office & Business Requirements
Corporate standards and business document formatting guidelines
Corporate Document Formatting Standards
Letterhead Design
Header Zone
Height: 25-50mm from top edge
Content: Logo, company name, contact info
Margins: 15mm minimum from edges
Footer Zone
Height: 15-25mm from bottom
Content: Legal info, registration numbers
Font Size: 8-10pt for legal text
Business Letter Format
Standard Margins
Top: 25mm (1") minimum
Bottom: 20mm (0.8") minimum
Left/Right: 20mm (0.8") standard
Typography
Body Text: 11-12pt serif or sans-serif
Line Spacing: 1.15-1.5x for readability
Paragraph: 6pt space after paragraphs
Presentation and Proposal Standards
Slide Dimensions
16:9 Widescreen
Standard for modern presentations
4:3 Traditional
Legacy format, still used
A4 Portrait
For printed handouts
Proposal Documents
Executive Summary
A4/Letter, 1-2 pages maximum
Technical Specs
A4/Letter, detailed formatting
Appendices
A3 for large diagrams/charts
Binding Considerations
Spiral Binding
15mm left margin minimum
Perfect Binding
20mm spine margin required
Ring Binding
25mm top margin for holes
Marketing Material Sizing Guidelines
Print Marketing
Brochures
Tri-fold: A4 (210×297mm) standard
Bi-fold: A3 (297×420mm) folded to A4
Z-fold: Custom sizes for unique layouts
Flyers & Leaflets
Standard: A5 (148×210mm) cost-effective
Premium: A4 (210×297mm) more space
Compact: A6 (105×148mm) for handouts
Business Cards & Stationery
Business Cards
Standard: 85×55mm (Europe)
US Standard: 3.5"×2" (89×51mm)
Japan: 91×55mm (meishi)
Compliment Slips
Standard: 210×99mm (1/3 A4)
US: 8.5"×3.67" (1/3 Letter)
Compact: 148×105mm (A6)
International Standards Compliance
ISO specifications, regional preferences, and cross-border requirements
ISO 216 Specifications and Tolerances
Technical Specifications
Base Dimensions
A0: 841 × 1189 mm (exactly 1 m²)
Aspect Ratio: 1:√2 (1:1.414)
Scaling: Each size is half the previous
Manufacturing Tolerances
Length/Width: ±1.5mm for sizes ≥A4
Small Sizes: ±1.0mm for A5 and smaller
Squareness: ±2mm maximum deviation
Quality Standards
Paper Weight Standards
Office Paper: 80 g/m² standard
Premium: 90-100 g/m² for presentations
Cardstock: 200-300 g/m² for covers
Whiteness & Opacity
Whiteness: 150+ CIE for premium
Opacity: 94%+ to prevent show-through
Brightness: 90+ ISO for laser printing
Regional Paper Size Preferences
Europe & Africa
Primary Standard
ISO A series (A4 dominant)
Government
A4 mandatory for official documents
Education
A4 notebooks, A3 for technical drawings
Americas
United States
Letter size dominant, Legal for law
Canada
Mixed: Letter (business), A4 (government)
Latin America
Transitioning from Letter to A4
Asia Pacific
Japan
JIS B series traditional, A4 increasing
China & India
A4 standard for business and education
Australia/NZ
A4 standard, some US influence
Import/Export and Cross-Border Printing
Document Requirements
Customs Documentation
Commercial Invoice: A4 preferred globally
Packing List: A4 standard format
Certificate of Origin: A4 with specific layouts
Shipping Labels
International: A4 or Letter acceptable
Thermal Labels: 4"×6" standard for shipping
Air Waybill: A4 format required by IATA
Printing Considerations
Multi-Region Campaigns
Design Once: Use A4 as base, adapt for Letter
Safe Zones: Keep content within 190×270mm
Bleed Areas: Account for different trim sizes
Cost Optimization
Local Printing: Use regional standard sizes
Paper Availability: Check local stock before design
Shipping Costs: Standard sizes reduce freight
Essential Conversion Factors & Formulas
Mathematical relationships and conversion formulas for paper dimensions
Millimeters to Inches Conversion Formulas
Basic Formulas
mm to inches
inches = mm ÷ 25.4
Example: 210mm ÷ 25.4 = 8.268 inches
inches to mm
mm = inches × 25.4
Example: 8.5" × 25.4 = 215.9mm
Quick Reference
1 inch25.4 mm
1 mm0.03937 inches
10 mm0.3937 inches
100 mm3.937 inches
Area Calculations for Different Paper Sizes
Area Formulas
Square Millimeters
Area = width × height
Square Meters
m² = (mm²) ÷ 1,000,000
Square Inches
in² = width" × height"
Common Areas
A40.0625 m²
A30.125 m²
Letter0.0603 m²
Legal0.0769 m²
Paper Weight Calculations
Weight Formula
Weight = Area × GSM
A4 @ 80gsm
5g per sheet
Ream Weight
500 sheets = 2.5kg
Scaling Factors Between Paper Series
ISO A Series Scaling
Sequential Scaling
A0 → A1: 70.7% (1/√2)
A1 → A2: 70.7% (1/√2)
A2 → A3: 70.7% (1/√2)
A3 → A4: 70.7% (1/√2)
Skip Scaling
A3 → A5: 50% (1/2)
A2 → A4: 50% (1/2)
A1 → A3: 50% (1/2)
Cross-Standard Scaling
A4 to Letter
Width Scale: 102.9% (wider)
Height Scale: 93.9% (shorter)
Area Scale: 96.6% (smaller)
Letter to A4
Width Scale: 97.2% (narrower)
Height Scale: 106.5% (taller)
Area Scale: 103.5% (larger)
Common Paper Size Examples & Applications
Real-world examples and specific use cases for different paper sizes
Business Cards and Stationery Sizing
Business Cards
Europe/International
85 × 55 mm
ISO/IEC 7810 ID-1 standard
United States
3.5" × 2" (89 × 51 mm)
ANSI standard
Japan (Meishi)
91 × 55 mm
JIS standard
Envelopes
DL Envelope
110 × 220 mm
Fits A4 folded in thirds
C5 Envelope
162 × 229 mm
Fits A4 folded in half
#10 Envelope (US)
4.125" × 9.5"
Fits Letter folded in thirds
Compliment Slips
Standard
210 × 99 mm
1/3 of A4 height
US Standard
8.5" × 3.67"
1/3 of Letter height
Compact
148 × 105 mm (A6)
Postcard size
Poster and Banner Dimensions
Standard Poster Sizes
A2 Poster
Size: 420 × 594 mm (16.5" × 23.4")
Use: Small promotional posters, notices
Viewing: Close-up reading distance
A1 Poster
Size: 594 × 841 mm (23.4" × 33.1")
Use: Event posters, presentations
Viewing: Medium distance visibility
A0 Poster
Size: 841 × 1189 mm (33.1" × 46.8")
Use: Large displays, trade shows
Viewing: Long distance visibility
Banner Formats
Roll-up Banner
Standard: 850 × 2000 mm
Wide: 1000 × 2000 mm
Premium: 1200 × 2000 mm
X-Banner
Small: 600 × 1600 mm
Medium: 800 × 1800 mm
Large: 1200 × 2000 mm
Outdoor Banner
Small: 1000 × 3000 mm
Large: 2000 × 6000 mm
Billboard: Custom dimensions
Book and Magazine Formats
Book Sizes
Paperback Novel
110 × 178 mm (B format)
Trade Paperback
135 × 216 mm (C format)
Hardcover
156 × 234 mm (Royal)
Textbook
189 × 246 mm (Crown Quarto)
Magazine Sizes
A4 Magazine
210 × 297 mm (Standard)
US Letter
8.5" × 11" (216 × 279 mm)
Digest
5.5" × 8.5" (140 × 216 mm)
Tabloid
11" × 17" (279 × 432 mm)
Technical Drawings
Engineering
A3 (297 × 420 mm)
Architecture
A2 (420 × 594 mm)
Large Scale
A1 (594 × 841 mm)
Site Plans
A0 (841 × 1189 mm)
Paper Size Standards Summary
Quick reference guide to international paper size systems
ISO A Series
The most widely used international standard. Each size is exactly half the area of the next larger size. A4 is the most common size worldwide.
Base: A0 = 1 square meter
Ratio: 1:√2 (1:1.414)
Usage: Global standard
ANSI Series
Used primarily in the United States and Canada. Letter (8.5" × 11") is the standard business size, while Legal (8.5" × 14") is used for legal documents.
Base: Letter size
Ratio: Various ratios
Usage: North America
Usage Tips
When printing internationally, A4 is the safest choice. For US business correspondence, use Letter size. Legal size is required for certain official documents.
Global: Use A4
US Business: Use Letter
Legal: Check requirements