A4 Paper Size in cm, mm and Inches, Plus the Envelopes That Fit A4

The A4 paper size is 210 x 297mm, or 21 x 29.7cm, which works out at about 8.27 x 11.69 inches. It is the standard sheet for printers, letters, forms and most office paperwork in the UK, set by the ISO 216 standard.

You will need these figures when you set up a printer, design a form, buy envelopes or pick a box for posting paperwork. Pack Solution stocks A4 paper, A4 label sheets and envelopes for posting A4 documents. We do not sell coloured A4 paper, card stock or photo paper.

Quick Picks: A4 Paper, Labels and Envelopes

These three cover most A4 jobs in an office or a dispatch area.

Best for everyday printing and copying

A4 Printing Paper

White A4 printer and copier paper sold by the ream, in a lighter 75gsm or an 80gsm weight.

• 210 x 297mm sheets
• 500 sheets per ream
• Standard 75gsm or Paper One Premium 80gsm

From £6.50 ex VAT (£7.80 inc VAT)

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Best for printing your own labels

A4 Sheet Labels

Self-adhesive labels on A4 sheets, in 10 layouts from 1 to 65 labels per sheet.

• 21 per sheet labels are 63.5 x 38.1mm
• Boxes of 500 sheets
• Print on an office printer

From £30.00 ex VAT (£36.00 inc VAT)

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Best for posting A4 documents flat

Board Back Envelopes

Envelopes with a stiff board back and a printed Do Not Bend warning, so papers arrive uncreased.

• C4 (324 x 229mm) takes A4 flat
• C4 and C5 in boxes of 125
• C6 in boxes of 250

From £12.00 ex VAT (£14.40 inc VAT)

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• A4 is 210 x 297mm, 21 x 29.7cm and about 8.27 x 11.69 inches.
• A4 Printing Paper comes in reams of 500 sheets, in 75gsm or 80gsm.
• A4 Sheet Labels come in 10 layouts, 1 to 65 labels per sheet, 500 sheets per box.
• Board Back Envelopes in C4 (324 x 229mm) take an A4 sheet flat.
• The M4 Capacity Mailer (312 x 250 x 70mm) takes A4 items up to 70mm thick.

A4 Paper Size in mm, cm and Inches

An A4 sheet measures 210mm wide and 297mm tall. Every other figure for A4 is a conversion of those two numbers.

The a4 sheet size mm figures, 210 and 297, are the ones printers and copiers use. If a print dialog asks for a custom page, enter 210 by 297mm and set the orientation separately.

A4 Paper in mm for Print Files

Print shops work in millimetres. If artwork runs to the edge of the page, they usually ask for 3mm of bleed on each side, so a full-bleed file for A4 paper in mm is 216 x 303mm, trimmed back to 210 x 297mm after printing. Keep text at least 5mm inside the trim line so nothing important is cut off. Office printers cannot print right to the edge, so leave a margin of a few millimetres on documents you print in-house.

A4 in cm

The a4 sheet size cm figure is 21 x 29.7cm. Rulers in UK schools and offices are often marked in centimetres, so this is the version most of us check by hand. A 30cm ruler laid along the long edge stops just 3mm past the end of the sheet.

A4 Size in Inches

Multiply by 0.03937 or divide by 25.4 to change millimetres into inches. That puts an A4 page in inches at 8.27 wide and 11.69 tall. Picture frames, scanners and some printers made for the US market list sizes in inches, so it helps to have both. When you need the A4 size in cm and inches together, write it as 21 x 29.7cm (8.27 x 11.69in).

How A4 Fits the A Series

A4 is one step in the ISO A series: each size is half the one before it, cut across the longer side. Fold an A4 sheet in half and you have A5; put two A4 sheets side by side and you have A3.

Every A size keeps the same proportions, a ratio of 1 to the square root of 2. That is why an A4 page shrinks onto A5 on a copier without any white margins. A0 is one square metre, and A4 is roughly a sixteenth of that.

The A4 page size also sets the size of most folders, plastic wallets and ring binders. If something is described as A4, it should take a 210 x 297mm sheet with a little room spare.

Envelopes That Fit A4

A C4 envelope takes A4 flat, C5 takes A4 folded once, and DL takes A4 folded into thirds. The C series is made a little larger than the matching A size so the paper slides in.

For certificates, contracts and photos that must stay flat, Board Back Envelopes have a stiff board back and a printed Do Not Bend warning. The C4 size takes an A4 sheet unfolded. The C5 size takes A5 prints and cards, and C6 suits A6 postcards and 6 x 4 inch photos.

For more on posting paperwork, read our guide to A4 and C4 envelopes for posting documents.

A4 Size Label Paper and Label Layouts

A4 label sheets are 210 x 297mm sheets of self-adhesive labels that run through an ordinary office printer. The layout, meaning how many labels sit on each sheet, decides the label size.

A4 Sheet Labels come in 10 layouts, all in boxes of 500 sheets.

The 24, 27 and 44 per sheet layouts fill the gaps: 64.0 x 33.9mm, 63.5 x 29.6mm and 48.5 x 25.4mm. The label sizes add up to slightly less than the full sheet because each layout leaves a margin for the printer to grip. When you print, set the scale to 100% or actual size. A setting such as fit to page shrinks the layout slightly, and by the bottom row the text has drifted off the labels. Print one test sheet on plain A4 paper, hold it against a label sheet up to the light, and adjust before you use the labels. Our A4 address labels guide goes through each layout in more detail.

Printer A4 Size Paper: Reams and Weights

Printer A4 size paper is sold in reams of 500 sheets, and the main choice is the weight in gsm. A higher gsm means a heavier, slightly thicker sheet.

A4 Printing Paper comes in two weights. Standard 75gsm is a lighter sheet for packing slips, picking lists and drafts. Paper One Premium 80gsm suits letters, quotes and reports that go to customers. Both are white and both are the full 210 x 297mm.

When you buy A4 size paper 500 sheets at a time, you are buying one ream. Most office printers hold a ream or less in the tray, so one ream is one refill. The weight is easy to work out: an A4 sheet is about a sixteenth of a square metre, so an 80gsm sheet weighs about 5g and a full ream of 80gsm weighs about 2.5kg.

Many businesses keep 75gsm by the dispatch printer and 80gsm in the office copier. The A4 printer paper guide compares 80gsm, 90gsm and 100gsm sheets if you print for customers.

Store reams flat, in their wrapper, somewhere dry. Paper takes on moisture from the air, and damp sheets curl and jam in the printer. Fan a new ream before you load it so the sheets separate cleanly, and do not fill the tray above its marked line.

Posting A4 Documents and Choosing an A4 Size Box

Thin A4 paperwork goes in a C4 envelope, while thicker A4 items need a mailer with depth. Measure the thickness of the finished item first, because that decides which one you need.

1. Count the sheets or measure the item at its thickest point.
2. For a few loose sheets, use a C4 board backed envelope so they stay flat.
3. For folders, books or boxed items, choose a mailer with a gusset.
4. Seal the envelope and add the address on a printed label.
5. Check the size band with the carrier before you buy postage.

Capacity Mailer Envelopes are rigid board envelopes with a 70mm expanding gusset. The M4 (312 x 250 x 70mm) is larger than an A4 sheet, so it works well as an A4 size box for books, ring binders and several documents at once. The M3 is 285mm long, which is too short for A4.

Best for A4 items that are too thick for an envelope

Capacity Mailer Envelopes

Rigid board envelopes with a 70mm expanding gusset for books, folders and boxed items.

• M4 (312 x 250 x 70mm) takes A4 items
• Four sizes, M1 to M4
• Boxes of 50

From £30.00 ex VAT (£36.00 inc VAT)

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If your A4 item needs a cardboard box rather than an envelope, our sibling guide to Royal Mail packaging boxes and bags covers boxes sized for each postage band.

A4 Compared With US Letter

US Letter is 8.5 x 11 inches (215.9 x 279.4mm), so it is about 6mm wider and 18mm shorter than A4. The two look alike on a desk but print differently.

Documents set up for Letter and printed on A4 often lose a strip at the side or gain a band of white space at the bottom. Before you print a file from a US template, change the a4 page size in the document settings as well as in the printer settings. Most UK printers default to A4, but a shared laptop may have been set to Letter. In software that measures in centimetres, the A4 page size cm values to enter are 21 wide by 29.7 high.

Ring binders, folders and envelopes made for A4 still take Letter paper, since Letter is shorter. The reverse is not always true, and A4 can stick out of a Letter folder.

A4 Paper Size Checklist

• A4 is 210 x 297mm, 21 x 29.7cm, about 8.27 x 11.69 inches.
• A5 is half of A4 and A3 is double.
• Use C4 for A4 flat, C5 for A4 folded once, DL for thirds.
• Set both the document and the printer to A4, not Letter.
• Choose 75gsm for volume printing and 80gsm for customer documents.
• Pick a label layout by the label size you need.
• Use a gusset mailer for A4 items thicker than a few sheets.
• Check carrier size limits before posting.

Stocking Up on A4 Supplies

Once you know A4 is 210 x 297mm, most choices follow from it: C4 envelopes for flat sheets, A4 label sheets for printing addresses, and reams of A4 paper for the printer. The stationery, labels and envelopes collections hold every item mentioned here, and the a4 size in inches and centimetres stays the same whichever you choose.

Frequently Asked Questions

What is the A4 paper size in mm, cm and inches?

A4 is 210 x 297mm. In centimetres that is 21 x 29.7cm, and in inches it is about 8.27 x 11.69. The size comes from the ISO 216 standard, which is used across the UK and Europe. The figures are the same for every A4 sheet, whatever its weight or finish.

What is the A4 sheet size in inch measurements, rounded?

Rounded to one decimal place, an A4 sheet is 8.3 x 11.7 inches. To two decimal places it is 8.27 x 11.69 inches. US Letter paper is 8.5 x 11 inches, so it is a little wider and shorter than A4, and a printer set to the wrong one will crop or shift the page.

Which envelope fits A4 paper?

A C4 envelope (229 x 324mm) takes an A4 sheet without folding. A C5 envelope takes A4 folded once, and a DL envelope takes A4 folded into thirds. Our Board Back Envelopes come in C4 (324 x 229mm), which keeps A4 certificates and photos flat in the post.

How many sheets are in an A4 size paper ream?

A ream holds 500 sheets. Our A4 Printing Paper is sold by the ream in two weights, Standard 75gsm and Paper One Premium 80gsm. Both are 210 x 297mm white sheets for printers and copiers set to A4.

Is A4 bigger than A5?

Yes. A4 is twice the area of A5. An A5 sheet is 148 x 210mm, so two A5 sheets side by side make one A4 sheet. A3 (297 x 420mm) is twice the area of A4. Each step in the A series halves the sheet across its longer side.

What A4 size label paper layouts are there?

Our A4 Sheet Labels come in 10 layouts, from 1 label per sheet (199.6 x 289.1mm) to 65 per sheet (38.1 x 21.2mm). The 21 per sheet layout has 63.5 x 38.1mm labels, which suit return addresses. Each box holds 500 A4 sheets.

Shop for This Job

• Stationery
• Labels
• Envelopes

Related Guides

• Royal Mail Packaging: Boxes and Bags That Fit Royal Mail Size Bands
• A4 Printer Paper Guide 80Gsm 90Gsm 100Gsm
• A4 C4 Envelopes Posting Documents

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