Ratio guide
A-series print sizes (A5–A1)
A-series print sizes are A5, A4, A3, A2 and A1; at 300 DPI the largest, A1, needs 7016 × 9933 px.
A-series paper (A5 to A1) is the ISO 216 standard used in the UK, EU, Australia and most of the world. Its 1:√2 shape means one A-file prints correctly at every A size.
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What sizes are A-series?
Every size below has the same shape, so one file at A1 (7016 × 9933 px) prints correctly at all of them. Pixel dimensions are inches × 300.
| Size (in) | Size (cm) | Pixels @ 300 DPI | Pixels @ 150 DPI | Frames |
|---|---|---|---|---|
| A5 (5.8 × 8.3 in) A5 photo size | 14.8 × 21 cm | 1748 × 2480 | 874 × 1240 | Small frames |
| A4 (8.3 × 11.7 in) A4 photo size | 21 × 29.7 cm | 2480 × 3508 | 1240 × 1754 | Home printing · A4 frames |
| A3 (11.7 × 16.5 in) A3 photo size | 29.7 × 42 cm | 3508 × 4961 | 1754 × 2480 | A3 frames |
| A2 (16.5 × 23.4 in) | 42 × 59.4 cm | 4961 × 7016 | 2480 × 3508 | Poster frames |
| A1 (23.4 × 33.1 in) | 59.4 × 84.1 cm | 7016 × 9933 | 3508 × 4967 | Poster frames |
What is the A-series ratio used for?
Any listing with international buyers. A4 prints at home on standard paper, A3 is the common step up, and A2/A1 are poster sizes at European print shops. Listing A-sizes avoids "will this fit my frame?" messages from outside the US.
Which frames fit a A-series print?
A4 (21 × 29.7 cm) and A3 (29.7 × 42 cm) frames are stocked in every homeware store outside the US; A2 and A1 are available from poster-frame ranges. Each A size is exactly half the previous one, so a mat cut for A3 displays an A4 print perfectly.
How much is cropped when you convert art to A-series?
1:√2 (0.707) is slightly wider than 2:3 (0.667) and narrower than 3:4. From 2:3 art you lose about 6% of the height; from 3:4 about 6% of the width. Most designs crop to A-series without any visible change.
In FrameReady, drag the photo to choose what's in the A-series frame (or use the arrow buttons), or switch that ratio to "Fit + pad" to keep the whole image.
What resolution do you need for a A1 print?
To be print-ready at A1 without upscaling, your source needs at least 7016 × 9933 px after cropping to A-series. The absolute floor (150 DPI) is 3508 × 4967 px. More on this in DPI explained. Below that, drop to the next size down rather than ship a soft file.
Frequently asked questions about the A-series ratio
What is A4 in pixels at 300 DPI?
2480 × 3508 px. A3 is 3508 × 4961, A2 is 4961 × 7016, A1 is 7016 × 9933.
Can I print an A-series file at US sizes?
Not exactly — 1:√2 matches no US frame. A4 printed on US Letter leaves small margins.
Why one file for all A sizes?
Every A size has the same proportion, so an A1 file scales down to A4 with no crop.