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.
1Image
Drop a tile or any image here
PNG, JPG, WebP, GIF, AVIF or SVG. A PNG's own DPI is read and shown. Nothing is uploaded.
Sample: peacock plume half drop, 646 × 508 px, no DPI stored.
3Result
- Pixel size
- 1,181 × 929 px
- Print size
- 20 × 15.73 cm (7.87 × 6.19 in)
- DPI stored
- 150 (5,906 pixels per metre)
- Change
- Enlarged 1.83× from 646 × 508 px
2Size & DPI
Height follows the tile: 15.73 cm.
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: pixels per unit on each axis, unit 1 = metre, placed before the image data.
- Spoonflower Help Center, 150 DPI: The Best Resolution for Spoonflower.
- canvas-size, 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.
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.