The pixels a print needs are its size in inches multiplied by the DPI. A4 (8.27 x 11.69 inches) at 300 DPI is 2480 x 3508 pixels, A3 is 3508 x 4961, 18x24 inches is 5400 x 7200 and 24x36 inches is 7200 x 10800. 300 DPI is the standard for anything seen up close; large posters viewed from a few feet away look fine at 150 DPI, which halves each dimension. This free calculator works out any size in inches, centimetres or millimetres at 150, 200 or 300 DPI, and lists every standard poster size so you can size artwork before you make it rather than upscale it afterwards.
Work out the pixels
You need 3,600 × 5,400 pixels (19.4 megapixels) at 300 DPI.
| Size | Inches | Pixels at 300 DPI | Megapixels |
|---|---|---|---|
| A5 | 5.83 × 8.27 | 1,748 × 2,480 | 4.3 |
| A4 | 8.27 × 11.69 | 2,480 × 3,508 | 8.7 |
| A3 | 11.69 × 16.54 | 3,508 × 4,961 | 17.4 |
| A2 | 16.54 × 23.39 | 4,961 × 7,016 | 34.8 |
| A1 | 23.39 × 33.11 | 7,016 × 9,933 | 69.7 |
| A0 | 33.11 × 46.81 | 9,933 × 14,043 | 139.5 |
| 5x7 | 5 × 7 | 1,500 × 2,100 | 3.1 |
| 6x8 | 6 × 8 | 1,800 × 2,400 | 4.3 |
| 8x10 | 8 × 10 | 2,400 × 3,000 | 7.2 |
| 11x14 | 11 × 14 | 3,300 × 4,200 | 13.9 |
| 11x17 | 11 × 17 | 3,300 × 5,100 | 16.8 |
| 12x18 | 12 × 18 | 3,600 × 5,400 | 19.4 |
| 16x20 | 16 × 20 | 4,800 × 6,000 | 28.8 |
| 16x24 | 16 × 24 | 4,800 × 7,200 | 34.6 |
| 18x24 | 18 × 24 | 5,400 × 7,200 | 38.9 |
| 20x30 | 20 × 30 | 6,000 × 9,000 | 54.0 |
| 24x32 | 24 × 32 | 7,200 × 9,600 | 69.1 |
| 24x36 | 24 × 36 | 7,200 × 10,800 | 77.8 |
| 28x40 | 28 × 40 | 8,400 × 12,000 | 100.8 |
| 30x40 | 30 × 40 | 9,000 × 12,000 | 108.0 |
| 30x40cm | 11.81 × 15.75 | 3,543 × 4,724 | 16.7 |
| 50x70cm | 19.69 × 27.56 | 5,906 × 8,268 | 48.8 |
| 10x10 | 10 × 10 | 3,000 × 3,000 | 9.0 |
| 12x12 | 12 × 12 | 3,600 × 3,600 | 13.0 |
| 14x14 | 14 × 14 | 4,200 × 4,200 | 17.6 |
| 16x16 | 16 × 16 | 4,800 × 4,800 | 23.0 |
| 18x18 | 18 × 18 | 5,400 × 5,400 | 29.2 |
| 20x20 | 20 × 20 | 6,000 × 6,000 | 36.0 |
300 DPI is the safe target for anything held in the hand. Posters viewed from across a room look fine at 150. Under 100 DPI prints visibly soft at any size.
How to use it
- Enter the print size — Type the width and height and choose inches, centimetres or millimetres. Any size works, including custom ones that are not in the standard table below.
- Pick a DPI — Choose 300 DPI for prints people hold or see up close, or 150 DPI for large posters viewed from across a room. 200 sits between the two.
- Read the pixel dimensions — The result shows the width and height in pixels and the megapixel count. Make or export your artwork at least this large before you add any text.
- Check the standard sizes — The table lists every standard poster size at the DPI you picked, so you can see the largest size your artwork can carry and stop offering anything above it.
The problem this solves
Artwork made too small is the commonest print fault in print-on-demand, and it is invisible on screen. Working out the pixel size you need before you start is a multiplication, but it is one people skip, and the cost turns up later as a soft print and a refund.
What it does
Any size, any unit
Enter width and height in inches, centimetres or millimetres. The calculator converts to inches and multiplies by the DPI you choose.
Three DPI targets
300 for prints held in the hand, 200 as a middle ground, 150 for large posters seen from across a room.
Every standard size listed
The A series, the common inch sizes from 5x7 to 30x40, metric posters and squares, with their pixel dimensions and megapixels at the DPI you picked.
Megapixels shown
Useful when an image generator or upscaler quotes output in megapixels rather than dimensions.
Where it lives in PSDmate
Free and open on this page. Inside PSDmate, every artwork is checked against the sizes you sell before it publishes, and low-resolution files are flagged on the listing.
Questions
How many pixels is A3 at 300 DPI?
3508 x 4961 pixels, about 17.4 megapixels. At 150 DPI it is 1754 x 2480.
How many pixels is 18x24 at 300 DPI?
5400 x 7200 pixels, about 38.9 megapixels. At 150 DPI it is 2700 x 3600.
Is 150 DPI good enough for a poster?
For large posters, usually yes. People stand further from a 24x36 than from an A4, so the eye cannot resolve the difference. Below 100 DPI prints look soft at any size.
Does changing the DPI setting in Photoshop add pixels?
No. Changing the DPI number without resampling only relabels the file. The pixel dimensions are what decide print quality.
Read more
- Poster Sizes in Pixels
- DPI, Resolution and Colour for Print-on-Demand
- Upscaling AI Art for Print
- Print file checker
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