How to Print an Image at an Exact Size (cm or inches)
Two ways to get a print at the precise dimensions you need — set the size directly, or measure a known distance and let GridPrint scale it for you.
Why "exact size" is harder than it should be
Printing an image at an exact size sounds simple, but most tools fight you on it. Printer dialogs default to "Fit to page," which silently shrinks or stretches the image to fill the paper. Photo apps measure everything in pixels, not centimeters or inches, so you never actually know how big the result will be. And if you only have a JPG someone sent you, there are no real-world dimensions baked in at all. The fix is to decide the physical size first, then print at true scale — and that is exactly what GridPrint is built for.
Two ways to set an exact size in GridPrint
Open GridPrint in your browser — no account, no install — and drag your image onto the page. From there you have two ways to lock in the physical size, depending on what you already know.
Method 1 — Type the exact width or height
Use this when you already know the final dimension you want — "make this 30 cm wide" or "I need it 8 inches tall." Enter the target width or height in the size fields and the other dimension scales proportionally so nothing gets distorted. If the result fits on a single sheet, you get a one-page PDF at exactly those dimensions. If it is bigger than your paper, GridPrint automatically splits it across multiple pages you can tape together.
Method 2 — "Set real size" by measuring a known distance
Use this when you do not know the image’s dimensions but you do have a real-world reference inside it — a ruler photographed next to an object, a known measurement on a sewing or woodworking pattern, the wheelbase of a scale model, or a body-placement mark on a tattoo design. Tap the 📏 "Set real size" tool, then tap two points on the part you want to control. Type how far apart those points should be on the printed page — for example, "the distance between these points should be 20 cm" — and GridPrint back-solves the size so that span comes out exactly right.
The tool works on any device, including your phone: pinch or scroll to zoom in for a precise tap, drag a point to nudge it, then press Apply. GridPrint uses whatever unit you have chosen in Settings — centimeters, inches, or millimeters — so the number you type matches the ruler you will check the print against.
Print at 100% scale (the step everyone gets wrong)
Download the PDF and open your printer dialog. This is the step that ruins most "exact size" prints: set the scale to 100%, also labelled "Actual size." Do not use "Fit to page," "Shrink to fit," or "Scale to fit" — any of those will resize the image and throw off your measurements. On most printers the setting is in the print dialog under Scale or Page Sizing; choose 100% or Actual Size, then print.
Printing larger than one page
When your exact size is bigger than a single sheet of A4 or Letter, GridPrint tiles the image across as many pages as needed and keeps every tile at true scale. Turn on overlap guides so neighbouring pages share a small margin, print them all at 100%, trim along the guide lines, and tape or glue them together. The assembled poster matches the size you set, down to the centimeter.
Centimeters or inches — set your unit first
GridPrint defaults to a sensible unit for your region but you can switch any time in Settings between centimeters, inches, and millimeters. Both the size fields and the "Set real size" tool follow that choice, so you can work in whatever your ruler uses. Switching units never re-scales the image — it only changes how the same physical size is displayed.