Text or a link it turns into a code, or an image of an existing code
Error correction
L, M, Q or H for codes it makes, default M
Decoder
jsQR, in your browser
Shows
The last step that decoded and the first that did not, side by side
The four tests
Test
What it does
Blur
Blurs the code more and more, measured as a fraction of one module
Viewing angle
Tilts the code away from square, in degrees
Resolution
Shrinks the image, measured in pixels per module
One module off a corner
Removes one module from a corner finder pattern
How results are judged
Test
Result
Verdict
Blur
0.30 of a module or more
Good. This is the figure that usually decides a real scan.
Blur
0.20 to 0.29
Workable, but tight. Print larger than you think you need.
Blur
Below 0.20
Fragile. Shorten the data or print much larger.
Viewing angle
45 degrees or more
Normal. Angle will not be your problem.
Viewing angle
Below 45
Lower than expected, which usually means the code is already dense.
Resolution
Reads at 2.5 px per module or fewer
Normal. On screen this code is hard to make too small.
Resolution
Needs more
Needs more pixels than usual per module.
Corner
Fails
Expected, and the point. Corner markers have no error correction.
Corner
Still reads
Unusual. The decoder recovered, but never rely on this.
The print size it suggests
The summary gives a printed width at 0.4 mm per module, including the quiet zone. For small codes that figure can be under 20 mm (0.8 in). Do not print below 20 mm even so: that floor from Print size and the scan badge still applies.