A design that looks perfect on screen can come back from the printer blurry, with text cut off at the edge or with a thin white border. Almost all of these problems come from three things: resolution, bleed and safe area. Here is what each means in plain language.
DPI: how many pixels do you need?
DPI (dots per inch) — often called PPI for digital images — tells you how many pixels are printed in each inch of paper. More pixels per inch means sharper print.
- 300 DPI — standard for things people hold close: business cards, invitations, brochures.
- 150 DPI — fine for flyers and posters seen from a short distance.
- 72–100 DPI — large posters and banners seen from far away.
To calculate pixels: inches × DPI, or millimetres ÷ 25.4 × DPI.
| Format | Physical size | 150 DPI | 300 DPI |
|---|---|---|---|
| Business card (US) | 3.5 × 2 in | 525 × 300 | 1050 × 600 |
| Business card (EU) | 85 × 55 mm | 502 × 325 | 1004 × 650 |
| Invitation 5 × 7 | 5 × 7 in | 750 × 1050 | 1500 × 2100 |
| A5 flyer | 148 × 210 mm | 874 × 1240 | 1748 × 2480 |
| A4 | 210 × 297 mm | 1240 × 1754 | 2480 × 3508 |
| US Letter | 8.5 × 11 in | 1275 × 1650 | 2550 × 3300 |
| A3 poster | 297 × 420 mm | 1754 × 2480 | 3508 × 4961 |
Ontools print makers start at these sizes and their PDF export uses the matching physical page size.
Bleed: why backgrounds need extra
Printers print on large sheets and cut them. The blade can shift by a millimetre. If your background color stops exactly at the edge, a hairline of white paper may appear. Bleed is extra background (usually 3 mm or 0.125 in on each side) that gets cut off.
If your printer asks for bleed: increase the canvas by 3 mm per side (about 36 px at 300 DPI, so +72 px in width and height), extend backgrounds to the new edges, and keep text where it was.
Safe area: keep text inside
The opposite problem: text too close to the edge may be cut. Keep all text and logos at least 3–5 mm inside the trim line. In the editor, a simple trick is to add a rectangle with only a border as a guide, design inside it, then delete it before exporting.
Color: RGB vs CMYK
Screens mix light (RGB); printers mix ink (CMYK). Very bright, saturated colors — electric blue, neon green — cannot be printed exactly and will look duller. Most print shops convert RGB PDFs automatically. For important jobs, ask for a printed proof.
Final checklist before printing
- Correct size and DPI for the product.
- Bleed added if the printer requires it.
- Text inside the safe area.
- Photos are high resolution (not screenshots or tiny web images).
- Spelling, phone numbers, dates and addresses checked twice.
- Exported as PDF.
Open the free Ontools editor — no account, no watermark, your files stay on your device.
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