How big should a 3D printed QR code be?
The size that matters is not the size of the code, it is the size of each little square. Below about 1.5 mm per square a 0.4 mm nozzle starts to blur them together and phones struggle. This guide tells you the minimum for your link.
It all depends on the number of squares
A QR code is a grid. The more characters in your link, the more squares (modules) the grid needs: a short link fits in 25 × 25, a long Google Drive link needs 37 × 37 or more. Divide the size of the code by the number of squares and you get the size of each square, which is the figure that decides whether the print comes out sharp.
Minimum size calculator
Fits a keychain, a magnet, a plaque or a stand.
Typical links and what they need (without a logo / with a logo in the middle):
| What you encode | Characters | Grid | Minimum size |
|---|---|---|---|
| Your own short domain | ~20 | 25 / 29 | 38 / 44 mm |
| Instagram profile | ~34 | 29 / 33 | 44 / 50 mm |
| Google review link (g.page) | ~39 | 29 / 37 | 44 / 56 mm |
| Wifi network (name + password) | ~44 | 33 / 37 | 50 / 56 mm |
| PDF menu shared from Google Drive | ~82 | 37 / 49 | 56 / 74 mm |
The logo in the middle costs size
A logo covers part of the code, so the code needs extra redundancy to survive it (error correction level H instead of M). That redundancy takes space: the same link jumps to a bigger grid, as the table shows. On a small keychain, choose between the logo and a comfortable size. On a plaque or a stand, there is room for both.
Make the link shorter
- Delete the tracking tail. Everything after a
?in a link copied from a social network (?utm_source=…,?igsh=…) is usually optional. Try the link without it before you print. - Use your own domain.
yourbar.com/menuis short and you control it forever. - Be wary of free link shorteners. They make the code smaller, but if the service closes or the link expires, your printed part stops working. A part lasts years.
- Print a link you can redirect. If you point the code to a page on your own site, you can change where it leads later without printing again.
Nozzle, layers and relief
With the usual 0.4 mm nozzle, a 1.5 mm square is three or four extrusion lines wide: enough for sharp edges. That is why the generator warns you in red below 1.5 mm. With a 0.2 mm nozzle you can go down to about 1 mm per square, which is useful for small keychains, at the cost of a longer print.
0.2 mm layers are perfect: the code is flat, so finer layers only add time. A relief of 0.8 to 1.2 mm is enough to feel and to look good; the scan depends on colour, not height. If your top surfaces come out rough, turn on ironing for the base: the background between squares becomes smoother and more even.
How far away does it scan?
A useful rule of thumb: a phone reads a QR code from about ten times its width, with good light and contrast. The default sizes of the generator are chosen with that in mind:
| Format | Default code size | Comfortable distance |
|---|---|---|
| Keychain | 45 mm | held in the hand |
| Fridge magnet | 55 mm | up to ~50 cm |
| Table stand | 70 mm | from a seated customer, ~70 cm |
| Wall plaque | 90 mm | up to ~90 cm |
For a sign people will scan from further away, such as a wall next to a door, scale the plaque up: 150 mm of code reads from a metre and a half.
Test before printing
Set your screen so the preview is the real size and scan it from the distance people will use. If it reads on the screen it will read on the part, provided the colours have enough contrast. After printing, test under the real lighting too: a spotlight reflecting off glossy filament is the most common cause of a code that "sometimes works".
Frequently asked questions
What is the smallest QR code I can 3D print?
With a 0.4 mm nozzle, about 1.5 mm per square: 38 mm for a very short link and around 44 mm for a typical Instagram or website link. With a 0.2 mm nozzle you can go to about 1 mm per square.
Why does a longer link need a bigger code?
Every character adds data, and the grid grows to hold it. A bigger grid in the same space means smaller squares, and small squares blur when printed.
Does a taller relief scan better?
No. The phone reads the colour difference, not the height. 0.8 to 1.2 mm is enough; more relief only adds shadows when the light comes from the side.
How far away can a 3D printed QR code be scanned?
Roughly ten times the width of the code with good light: a 90 mm plaque reads from about 90 cm.
Can I scale the 3MF in my slicer?
Yes, scaling up is always safe. Scaling down shrinks the squares too, so check that they stay above 1.5 mm. It is better to choose the size in the generator, which also keeps the hole and the text in proportion.