Paper Size Converter
A4, Letter, B & C series.
A4, Letter, B & C series.
How to use Paper Size Converter
- Pick a paper size from the A, B, C, or US series
- Read its dimensions in millimetres, centimetres, and inches
- Copy the print-scaling percentage to fit it onto another size
About Paper Size Converter
Paper sizes come in two incompatible systems, and this converter covers both. Look up any size in millimetres, centimetres and inches — the complete ISO A series (A0 down to A10), the B and C series, and the North American set of US Letter, Legal and Tabloid — so you can confirm that A4 is 210 × 297 mm, read the same size in cm, or get it in inches without doing the maths yourself.
The number most converters leave out is the scaling percentage you actually type into a print dialog. When A4 has to fit on US Letter it's about 94%; going from Legal to A4 needs a different figure, and the tool works out the exact percentage for any pair of sizes. That's also the number you need when a PDF was built for one paper size and you have to print it on another — the converter gives the percent, you set it in your print settings.
Because every dimension is given precisely in millimetres, you can also use it to size a design or work out the pixel count for an image at a chosen DPI before you export. There's nothing to install, no sign-up, and no file to upload: everything is calculated in your browser, so your documents never leave your computer.
Frequently asked questions
- What is A4 in inches?
- A4 is 8.27 × 11.69 inches, or 210 × 297 mm. The tool shows every size in mm, cm and inches at once.
- What is A4 in cm?
- A4 is 21.0 × 29.7 cm. Each size is listed in centimetres right alongside its millimetre and inch equivalents, so you can read whichever unit you need.
- How do I print an A4 document on US Letter paper?
- Set your printer's scale to about 94% (or choose 'Fit to page'). A4 is taller than Letter, so shrinking it slightly stops the bottom being cut off. The scaling calculator gives the exact figure for any pair of sizes.
- How do I convert Legal paper size to A4?
- Legal is 216 × 356 mm and A4 is 210 × 297 mm, so Legal is both a touch wider and much longer. Pick the two sizes and the calculator returns the reduction — roughly 83% — that fits a Legal page onto A4 without cropping. Enter that percent in your print or export settings.
- Can I convert the paper size of a PDF?
- This tool doesn't resize the PDF file itself, but it gives the exact scaling percentage to change its printed paper size. Choose the source and target sizes here, then type that percent (or select 'Fit to page') in your PDF viewer's print dialog.
- What's the difference between A4 and US Letter?
- A4 (210 × 297 mm) is a little narrower and noticeably taller than US Letter (216 × 279 mm), so the two aren't interchangeable without scaling.
- How do I convert pixels to a paper size?
- Pixels depend on resolution, so you need a DPI value first. The tool gives the precise millimetres for each size; multiply by your DPI and divide by 25.4 to get pixels — for example, A4 at 300 DPI works out to 2480 × 3508 px.
- What size should an image be to fill an A4 page?
- A4 measures 210 × 297 mm. For a full-page image at 300 DPI, make it about 2480 × 3508 pixels. The converter gives the exact mm for any size, so you can set your canvas at whatever DPI you're exporting at.
- What are the B and C paper series for?
- The B series sits between the A sizes and is used for posters and books, while the C series is sized for envelopes — a C4 envelope holds an unfolded A4 sheet and a C5 holds a folded one.
- How do the ISO paper sizes work?
- Each size is the previous one halved while keeping the same proportions, with dimensions rounded down to whole millimetres — so A5 is half of A4, A6 is half of A5, and so on down the series.
- Is this paper size converter free?
- Yes, it's completely free with no sign-up and nothing to upload. Every dimension and scaling percentage is calculated in your browser, so your files stay on your device.