Preparing an image for print and wondering how many pixels you need for A4? The answer depends on the resolution (DPI) you're targeting. This article provides pixel dimensions for all major paper sizes at multiple DPI levels.
Free Tool
Image Resizer
Resize images to exact dimensions. Includes presets for social media covers and ID photos.
Try it now →A-Series Paper — Pixel Dimensions by DPI
The most common paper sizes for printing.
A-series sizes (A0–A7)
| Paper | mm (H × W) | 72 DPI | 150 DPI | 300 DPI | 600 DPI |
|---|---|---|---|---|---|
| A0 | 1189 × 841 | 3370 × 2384 | 7024 × 4972 | 14043 × 9933 | 28087 × 19866 |
| A1 | 841 × 594 | 2384 × 1684 | 4967 × 3508 | 9933 × 7016 | 19866 × 14031 |
| A2 | 594 × 420 | 1684 × 1191 | 3508 × 2480 | 7016 × 4961 | 14031 × 9921 |
| A3 | 420 × 297 | 1191 × 842 | 2480 × 1754 | 4961 × 3508 | 9921 × 7016 |
| A4 | 297 × 210 | 842 × 595 | 1754 × 1240 | 3508 × 2480 | 7016 × 4961 |
| A5 | 210 × 148 | 595 × 420 | 1240 × 874 | 2480 × 1748 | 4961 × 3496 |
| A6 | 148 × 105 | 420 × 298 | 874 × 620 | 1748 × 1240 | 3496 × 2480 |
| A7 | 105 × 74 | 298 × 210 | 620 × 437 | 1240 × 874 | 2480 × 1748 |
B-Series Paper — Pixel Dimensions by DPI
B-series sizes are slightly larger than their A-series counterparts and are commonly used in Japan.
B-series sizes (B0–B7)
| Paper | mm (H × W) | 72 DPI | 150 DPI | 300 DPI | 600 DPI |
|---|---|---|---|---|---|
| B0 | 1456 × 1030 | 4127 × 2920 | 8598 × 6083 | 17197 × 12165 | 34394 × 24331 |
| B1 | 1030 × 728 | 2920 × 2064 | 6083 × 4299 | 12165 × 8598 | 24331 × 17197 |
| B2 | 728 × 515 | 2064 × 1460 | 4299 × 3043 | 8598 × 6083 | 17197 × 12165 |
| B3 | 515 × 364 | 1460 × 1032 | 3043 × 2150 | 6083 × 4299 | 12165 × 8598 |
| B4 | 364 × 257 | 1032 × 729 | 2150 × 1518 | 4299 × 3035 | 8598 × 6071 |
| B5 | 257 × 182 | 729 × 516 | 1518 × 1075 | 3035 × 2150 | 6071 × 4299 |
| B6 | 182 × 128 | 516 × 363 | 1075 × 756 | 2150 × 1512 | 4299 × 3024 |
| B7 | 128 × 91 | 363 × 258 | 756 × 538 | 1512 × 1075 | 3024 × 2150 |
Other Common Sizes
Postcard, business card, photo, and letter sizes
| Paper | mm (H × W) | 72 DPI | 150 DPI | 300 DPI | 600 DPI |
|---|---|---|---|---|---|
| Postcard (JP) | 148 × 100 | 420 × 283 | 874 × 591 | 1748 × 1181 | 3496 × 2362 |
| Business card (JP) | 91 × 55 | 258 × 156 | 538 × 325 | 1075 × 650 | 2150 × 1299 |
| L-size photo | 127 × 89 | 360 × 252 | 750 × 526 | 1500 × 1051 | 3000 × 2102 |
| 2L-size photo | 178 × 127 | 504 × 360 | 1051 × 750 | 2102 × 1500 | 4205 × 3000 |
| US Letter | 279 × 216 | 791 × 612 | 1648 × 1276 | 3295 × 2551 | 6590 × 5102 |
Recommended DPI by Use Case
Before looking up pixel counts, decide on the right DPI for your purpose.
| Use Case | Recommended DPI | Why |
|---|---|---|
| Website / Social media | 72 DPI | Screen display only; keeps file sizes small |
| Internal docs / Home printing | 150 DPI | Adequate quality for text-heavy content |
| Flyers / Brochures | 300 DPI | Professional print standard; photos look sharp |
| Large posters | 150–200 DPI | Viewed from a distance, so lower DPI is fine |
| Ultra-fine print | 600 DPI | For small text or thin lines |
How to Calculate Pixels from Paper Size
You can compute the pixel dimensions for any paper size and DPI using a simple formula.
Formula: mm ÷ 25.4 × DPI = pixels
Example: A4 (297 × 210 mm) at 300 DPI
- Height: 297 ÷ 25.4 × 300 = 3,508 pixels
- Width: 210 ÷ 25.4 × 300 = 2,480 pixels
The 25.4 divisor converts millimeters to inches (1 inch = 25.4 mm).
Example: Postcard (148 × 100 mm) at 300 DPI
- Height: 148 ÷ 25.4 × 300 = 1,748 pixels
- Width: 100 ÷ 25.4 × 300 = 1,181 pixels
Free Tool
Image Resizer
Resize images to exact dimensions. Includes presets for social media covers and ID photos.
Try it now →FAQ
How many pixels is A4 at 300 DPI?
At 300 DPI, A4 is 3508 × 2480 pixels. At 72 DPI (web), it's 842 × 595 pixels.
What DPI should I use for printing?
300 DPI is the professional print standard. Home printers work fine at around 200 DPI. Web images only need 72 DPI.
What does DPI mean?
DPI stands for dots per inch — the number of dots (or pixels) packed into one linear inch. Higher DPI = sharper image, but also larger file size.
How many pixels is B5 at 300 DPI?
At 300 DPI, B5 (257 × 182 mm) is 3035 × 2150 pixels.
How do I calculate pixels from paper size?
mm ÷ 25.4 × DPI = pixels. For example, the 210 mm width of A4 at 300 DPI: 210 ÷ 25.4 × 300 ≈ 2,480 pixels.
Summary
To convert any paper size to pixels, remember: mm ÷ 25.4 × DPI. Use 300 DPI for print and 72 DPI for web as your baseline.
Bookmark this chart so you have the numbers ready whenever you're preparing images for print or digital use. When you need to resize an image to exact pixel dimensions, sakutto's image resize tool handles it right in your browser.
Free Tool
Image Resizer
Resize images to exact dimensions. Includes presets for social media covers and ID photos.
Try it now →