How to use the Digital Canvas Size for Print calculator
- Pick the print. Choose a size from Print size or type a Trim width and Trim height (trim is the finished size after cutting). Switch between in, cm and mm, and between Portrait and Landscape, at any time.
- Choose the resolution. Tap 300, 240 or 150 under Resolution (DPI), or type your own value in the box beside them.
- Add bleed and a safe margin. Set Bleed per side and Safe margin to what your printer asks for. The result, the diagram and the table all update as you change them.
- Set up the file. Open the tab for your app — Procreate, Photoshop, Krita or Clip Studio Paint — and follow the steps, which already contain your numbers.
- Take the numbers with you. Copy settings gives you a plain-text spec for your notes or the print shop. Download guide PNG saves a transparent overlay at the exact canvas size with the bleed tinted red and the safe area dashed in blue; drop it on the top layer and hide it before export.
Pixels decide the print, DPI only labels it
A digital canvas is a grid of pixels. DPI (dots per inch, which apps also call PPI) is a note stored in the file that says how many of those pixels should fill one printed inch. Change the note and nothing on the canvas moves: a 2400 × 3000 px painting prints at 8 × 10 in at 300 DPI, or at 10 × 12.5 in at 240 DPI, from exactly the same pixels.
That is why the question to ask is “how many pixels do I need?” rather than “which DPI should I set?”. The answer depends on how close people stand:
- 300 DPI is the standard for art prints, zines and anything held in the hand.
- 240 DPI is plenty for most photo-paper prints and wall pieces viewed from a step back. It needs 36% fewer pixels than 300 DPI, which can be the difference between a workable canvas and one that runs out of layers.
- 150 DPI suits posters and banners read from across a room.
Bleed is extra artwork beyond the trim line. Guillotines and die cutters drift slightly, so printers ask you to paint past the edge — usually 0.125 in per side in the US and 3 mm in the UK and Europe — and keep text inside a safe margin of a similar width. At 300 DPI, 0.125 in is 37.5 px per side; 3 mm is 35.4 px.
Why big canvases cost you layers
Painting apps keep every layer as raw pixels while you work: four bytes per pixel (red, green, blue, alpha) at 8 bits per channel, eight bytes at 16 bits. Compression only happens when the file is saved. So memory grows with the pixel count, not with how much you’ve painted. A 2048 × 2048 px canvas needs 16.8 MB per layer. A4 at 300 DPI (2480 × 3508 px) needs 34.8 MB, about twice as much, and an 18 × 24 in poster at 300 DPI (5400 × 7200 px) needs 155.5 MB — 9.3 times the 2048 square.
Procreate turns this into a hard cap. Its Custom canvas screen shows Maximum layers for the size you enter, and that number depends on both the canvas and your iPad’s memory, so two iPads can show different caps for the same file. Instead of guessing, compare canvases with the layer memory of 2048 × 2048 figure in the calculator: double it and you should expect roughly half the layers. The same logic explains why Photoshop slows down on large 16-bit files long before it refuses to open them.
Pixel sizes for common prints
All at 300 DPI. The bleed column adds 0.125 in on every side; the last column is memory per 8-bit layer with bleed.
| Print size | Trim only | With 0.125 in bleed | Per layer |
|---|---|---|---|
| 5 × 7 in | 1500 × 2100 px | 1575 × 2175 px | 13.7 MB |
| A5 (148 × 210 mm) | 1748 × 2480 px | 1823 × 2555 px | 18.6 MB |
| 8 × 10 in | 2400 × 3000 px | 2475 × 3075 px | 30.4 MB |
| US Letter (8.5 × 11 in) | 2550 × 3300 px | 2625 × 3375 px | 35.4 MB |
| A4 (210 × 297 mm) | 2480 × 3508 px | 2555 × 3583 px | 36.6 MB |
| 12 × 12 in | 3600 × 3600 px | 3675 × 3675 px | 54.0 MB |
| 11 × 14 in | 3300 × 4200 px | 3375 × 4275 px | 57.7 MB |
| A3 (297 × 420 mm) | 3508 × 4961 px | 3583 × 5036 px | 72.2 MB |
| 12 × 18 in | 3600 × 5400 px | 3675 × 5475 px | 80.5 MB |
| 18 × 24 in | 5400 × 7200 px | 5475 × 7275 px | 159.3 MB |
European printers usually want 3 mm instead, which makes A4 2551 × 3579 px.
Tips from practice
Get the printer’s template before you open the app. Print-on-demand shops and local printers often publish exact pixel sizes, bleed and safe zones per product. Their numbers beat any rule of thumb, including ours.
Choose the aspect ratio, not just the size. 8 × 10 (4:5), 11 × 14 and A4 are all different shapes, so one canvas can’t fill all three without cropping. If you plan to sell several sizes, paint for the most extreme ratio and leave room to crop, then check each crop with the Aspect Ratio Calculator.
Decide RGB or CMYK on day one. Procreate lets you change profiles within a family later, but not jump between RGB and CMYK. Most artists paint in RGB (sRGB is the safe choice for labs and online shops) and let the printer convert. Choose CMYK only when a printer insists, because its smaller gamut dulls bright blues and greens the moment you pick them.
Don’t plan to upscale. Enlarging a finished painting by 200% invents pixels and softens edges, especially line art. If layers are tight, drop to 240 DPI or split the piece into sections rather than starting small.
Keep the guide on its own locked layer. Leave the downloaded guide PNG as the top layer while you compose, so lettering stays inside the blue line, and hide it before exporting. To check how a finished file will print at other sizes, run its pixel dimensions through the DPI & Print Size Calculator.