Convert Paper Size

A4 (210 × 297 mm) is slightly taller and narrower than US Letter (8.5 × 11 in or 216 × 279 mm). A4 is part of the ISO standard used worldwide, while Letter is the standard in the US and Canada. A4 has a consistent aspect ratio that allows easy scaling.

Paper standards developed regionally before global standardization. The ISO A-series was designed with mathematical precision (each size is exactly half the area of the next), while US sizes evolved from practical printing needs. The US continues to use its traditional sizes despite global ISO adoption.

Yes, but with some adjustments. A4 is taller than Letter, so content may be cut off or scaled down. Most printers offer 'fit to page' or 'scale to fit' options. For best results, design documents specifically for your target paper size.

B-series sizes are intermediate sizes (larger than A but smaller than the next A size) often used for books, posters, and magazines. C-series sizes are designed for envelopes - C4 fits A4 unfolded, C5 fits A5 unfolded, etc.

For unfolded documents, use C-series envelopes (C4 for A4, C5 for A5). For folded documents, you can use smaller envelopes. Always check that your printer can handle the envelope size and that postal services accept it.

Yes! The A-series extends both ways: A7, A8, A9, A10 get progressively smaller, while A0 can be extended to larger formats. However, A6 to A0 covers most practical needs. Very large formats are often custom-made for specific applications.