Canvas Resolution by MP and DPI

Canvas Resolution for Print (Megapixels & DPI)

A print only looks clean when there are enough pixels to fill the physical size at the DPI (dots per inch) you're aiming for. So the math just turns inches into pixels: pixels = inches × DPI. Working in centimeters? Then it's pixels = (cm / 2.54) × DPI. To get total megapixels, multiply width_px by height_px and divide by 1,000,000.

Good photo printing almost always assumes 300 DPI. At that density an A4 sheet (21×29.7 cm) needs 2480×3508 px, roughly 8.7 MP, and an 8×10 inch photo (20×25 cm) needs 2400×3000 px, about 7.2 MP. Big outdoor banners are a different story. Since nobody stands 2–3 m away and counts pixels, 100–150 DPI is plenty. Magazines and books stick with 300 DPI; newspapers get away with 150–200 DPI.

Applications

Designers reach for this when prepping print-shop files in Adobe Photoshop (Image > Image Size), Illustrator, Affinity Photo, or GIMP. Photographers lean on it to check whether their camera actually has the resolution a given print size demands. And print operators use it to size canvases for banners, posters, business cards, photo books, and those gallery-wrapped canvas prints.

FAQ

Can I upscale a low-res image to 300 DPI? Resampling invents pixels, not actual detail. AI upscalers like Topaz, Gigapixel, and Photoshop Super Resolution do a decent job, but they still can't fake what a genuinely high-resolution shot captures.

What DPI for a smartphone wallpaper or web image? On screens, what matters is the display's pixels per inch (PPI), usually somewhere between 72 and 326. For the web, just match the pixel dimensions and forget the DPI metadata, it does nothing.

Does CMYK conversion change required resolution? No. What you need comes from print size and viewing distance, not the color mode. CMYK files do tend to be bigger and compress differently, though.