How to Print a Star Map — At Home, at a Shop or Online

Your digital order contains the map at three sizes, each as a PNG and a PDF at 300 DPI.

Use the PDF for shops and online labs. A PDF carries its physical dimensions inside it. Upload the 18 x 24 PDF and the shop's system knows it is 18 x 24; nobody has to type in a size or guess at a scale. Most professional and drugstore systems accept PDF for posters.

Use the PNG at home and anywhere an image is required: phone wallpapers, photo-book apps, some kiosk machines. Some online labs also prefer PNG or JPG for photo prints; if so, upload the PNG in the size you ordered and check that the preview shows no cropping.

Match the file to the print size. Print the 12 x 16 file at 12 x 16, the 18 x 24 file at 18 x 24 and so on. Each was rendered natively at that size, so lines and lettering are drawn for that scale.

Any inkjet or photo printer will do. Most home printers stop at letter or A4 paper, so a home print will be smaller than 12 x 16, which is fine for a desk frame or a gift you want in hand tonight. If your printer takes larger sheets, use them.

Settings that matter, in order of importance:

1. Paper type. Tell the printer exactly what is in the tray: "Photo Paper Matte", "Premium Glossy", and so on. This single setting controls how much ink it lays down. Leaving it on "Plain Paper" is the most common cause of a washed-out, grey sky.
2. Quality. Highest, best, or "Photo" quality. It is slower and uses more ink. It is worth it.
3. Scaling. Set to 100%, "Actual size" or "No scaling". Turn off "Fit to page" and "Shrink to fit". If the file is larger than the sheet, the printer or your PDF viewer will offer to scale it down; choose "Fit" only when you have consciously accepted a smaller print, and never "Fill" or "Stretch".
4. Borderless. Most photo printers support it on photo paper. Turn it on if you want the design to run to the paper's edge; leave it off if you plan to mat the print, since the mat covers the margin anyway.
5. Colour management. Let the printer manage colour and leave the file as sRGB. Do not choose a different profile unless you know why.

Let the print dry flat for an hour before framing, longer for dense dark designs.

Prices below are approximate, vary by region and finish, and change; treat them as bands, and check the current price before you order.

Two things to watch at any counter. First, the size: not every shop offers 12 x 16, 18 x 24 and 24 x 36 exactly. If the nearest size has a different proportion, choose "fit" rather than "fill" and accept a small white margin, or order a custom size. Second, the paper: a "poster" option at an office-supply store is often thin, plain paper meant for signs. Ask for photo or matte presentation paper, or use the photo-print department instead of the copy department.

Matte photo paper has no reflection, hides fingerprints and looks composed under any light. It softens the very deepest blacks slightly. It is the safe choice for every design and the best choice for the pale paper and heart white designs.

Semi-gloss, lustre or satin is the middle path: a faint sheen that gives dark skies their depth, with far less glare than gloss. It is what our own framed prints use. If you want the galaxy, navy or noir design to look as deep as it does on screen, this is the finish.

High gloss is best avoided for star maps. On a mostly dark image it behaves like a mirror, and you end up seeing the window instead of the stars.

Fine-art or archival papers (cotton rag, textured matte) are offered by the online labs. They cost more and look quietly beautiful, especially for the paper design and for memorial maps. Choose them when the print is going into a good frame for a long time.

The files are sRGB, the standard colour space for consumer printers, print shops and photo labs. You do not need to convert or assign anything. If a shop asks which profile the file is in, the answer is sRGB. If a lab offers to "soft proof" or convert to their printer profile, letting them do so is fine; they know their machine.

Fit to page left on. The map prints smaller than intended, sometimes with an odd margin. Set scaling to 100% unless you have chosen to shrink it.

Wrong size file. Printing the 12 x 16 file at 24 x 36 stretches 3600 pixels across two feet and the stars turn soft. Use the file that matches the size.

Plain paper. Copier paper soaks up ink and turns a night sky grey. Use photo paper, and tell the printer you have.

Banding in dark areas. Faint stripes or blotches in the background come from a draft-quality setting, a heavily compressed copy of the file, or thin paper. Highest quality, the original file, real photo paper.

Stretching to fill a different proportion. If a shop's size is not 3:4, never let the system stretch the image to fill it. Circles become ovals. Choose fit, accept a margin, and mat it.

12 x 16, 18 x 24 and 24 x 36 are stock frame sizes in the US, so a frame is a same-day purchase. A mat makes any print look more considered; look for a frame one size up with a mat cut to your print size. Acrylic fronts are lighter and safer than glass over a bed or a cot. Hang the map out of direct afternoon sun. If you would rather skip all of this, the framed star map arrives printed, mounted in a black wood frame, and ready to hang. For choosing between sizes, see star map sizes.