--- title: "Print-Ready PNG Export: Set Size and DPI | Pattern Plume" description: "Pick a print size and DPI to get the exact pixel size, resample a seamless tile, fill a whole length, or just set a PNG's DPI without touching its pixels." url: https://patternplume.cfd/print-ready-export/ --- # Print-ready export at DPI Choose how big a repeat should print and at what DPI. Get the exact pixel size and a PNG that carries its DPI, or fill a whole length of fabric or paper. ## Result Sending artwork to a print shop or print-on-demand site you have not used before? Look up who is behind its domain with [WebTraceCheck's free DNS and domain lookup](https://webtracecheck.com/dns-lookup) before you upload files or pay. ## Pixels, inches and the DPI in a PNG A printed size needs a number of pixels: **pixels = inches × DPI**, with 2.54 cm to the inch. Ask your printer which DPI they print at; Spoonflower, for example, works at 150 DPI and sizes every design by dividing its pixels by 150. Then pick what to export: - **One repeat at print size** resamples the tile to the width you enter. The edges are blended with the opposite side, so the tile still repeats without a line. When it has to be enlarged more than 1.5 times you get a warning, because enlarging adds pixels but no detail. - **Fill a length** repeats the resized tile over a whole sheet and writes the PNG row by row, so it is not limited by the browser's canvas size. **Fit whole repeats across** adjusts the repeat width so the pattern is not cut at the right edge. - **Set the DPI only** keeps every pixel and changes the stored DPI, which changes the size other programs print at. For a PNG file, every byte apart from that chunk is kept as it was. PNG stores DPI in a small `pHYs` chunk as pixels per metre, a whole number: 150 DPI is saved as 5,906 per metre, which some programs display as 150.01. Without it, each program has to guess the size. **Example:** to print the 646 px wide sample tile 8 in (20.32 cm) wide at 300 DPI it needs 2,400 px across, an enlargement of about 3.7 times; at 150 DPI it needs 1,200 px, about 1.9 times. Filling 140 × 100 cm at 150 DPI makes an 8,268 × 5,906 px PNG of 48.8 megapixels. ## Sources - W3C, [PNG Specification (Third Edition), pHYs chunk](https://www.w3.org/TR/png-3/#11pHYs): pixels per unit on each axis, unit 1 = metre, placed before the image data. - Spoonflower Help Center, [150 DPI: The Best Resolution for Spoonflower](https://support.spoonflower.com/hc/en-us/articles/9327411118349-150-DPI-The-Best-Resolution-for-Spoonflower). - canvas-size, [test results](https://jhildenbiddle.github.io/canvas-size/#/?id=test-results): largest canvas per browser (16,384 × 16,384 in Chrome, Edge and desktop Safari; 4,096 × 4,096 on iPhone and iPad). - MDN Web Docs, [The canvas element: maximum canvas size](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements/canvas). ## Questions **Does changing the DPI change my image?** Setting the DPI only changes a number stored in the file, which tells other programs how big to print it. The pixels stay exactly the same. Resizing to a print size is different: it resamples the pixels to a new width and height. **What DPI should I choose?** Whatever your printer asks for. Spoonflower prints fabric and wallpaper at 150 DPI and converts every upload to it. Exporting at a higher DPI than the printer uses adds file size but not detail; a lower one leaves the printer to enlarge your file. **Why does my export look blurry?** The tile had fewer pixels than the print size needs, so it was enlarged. Start from bigger artwork, choose a smaller print size or a lower DPI, or redraw the motif in a vector app and export it larger. **How big can an export be?** One resized repeat has to fit a browser canvas: up to 16,384 × 16,384 pixels in Chrome, Edge and desktop Safari, and 4,096 × 4,096 on iPhone and iPad. Filled sheets are written row by row without a canvas, up to 65,535 pixels a side and a billion pixels in total, but big files take a while and many viewers struggle to open them. **Will the tile still repeat seamlessly after resizing?** Yes. Before resampling, the tile is surrounded by copies of its own opposite edges, so the smoothing at each border blends with the neighbouring repeat instead of with empty space. **Are colour profiles kept?** Resized and filled exports are drawn through the browser canvas, which works in sRGB with 8 bits per channel, so an embedded colour profile or 16-bit depth is not carried over. Setting the DPI only on a PNG keeps all of its other chunks, profile included.