9 Reasons Your QR Code Is Not Scanning (and How to Fix Each)

May 28, 2026 · 6 min read

Quick Answer

QR codes usually fail because they are too small, low-contrast, missing a quiet zone, or pointing at a broken or expired destination. Use a high-contrast static code, leave a clear margin, and test on two phones before printing.

A QR code that will not scan is almost always a fixable design or destination problem, not a fault with QR codes themselves. Work down this list in order and you will usually find the cause in the first three items.

If you only have time for one check, re-scan your code with two different phones before you print anything. Most failures are caught in that 30-second test.

How we measured: every QR example in this post was generated by Link2QR's own QR generator and then checked with jsQR, the open-source decoder that the Link2QR decode and scanner tools use. Phone cameras use other decoders, so treat these results as relative guidance, not absolute limits.

1. It is too small for the scan distance

A code needs to be at least 2 cm (about 0.8 inches) per side for close-range scanning like business cards and flyers. For posters and signage, scale up: a good rule is that scanning distance should be no more than 10 times the code's width.

Small QR code for a short link, 29 by 29 modules, that still scans — A 31-character link (Version 3, 29 x 29 modules) still decoded after we shrank it to 92 pixels wide.

Small, dense QR code for a long link with tracking parameters, 57 by 57 modules, too crowded to scan — A 199-character link with tracking parameters (Version 10, 57 x 57) did not decode at the same size. More data needs a bigger print.

Check the QR code size guide →

2. The contrast is too low

Scanners rely on a strong difference between dark modules and a light background. Pastel-on-white or dark-on-dark will fail. Keep dark modules on a light background with a contrast ratio of at least 4 to 1.

Black QR code on a white background, easy to scan — Black on white: decoded.

QR code in light gray on white, too faint to scan — Light gray #e6e6e6 on white (about 1.25 to 1): did not decode. The lightest gray that still decoded was #909090, about 3.2 to 1, under this post's 4 to 1 advice, so leave a margin.

3. The colors are inverted

A light code on a dark background confuses many phone cameras, which expect dark patterns on light. If you want a dark look, keep the code itself dark and put it inside a light rounded panel.

Inverted QR code with white modules on a dark background — White on dark: jsQR did not decode it with its inverted check turned off, and did with it on. Whether a scanner app tries the inverted reading depends on the app.

4. There is no quiet zone

QR codes need a clear margin, called the quiet zone, of at least four modules on every side. Text, logos, or borders crowding the edge stop the scanner from finding where the code begins and ends.

QR code on a dark background with no white margin around it — No margin on a dark background: did not decode.

The same QR code with a white margin of 4 modules around it — The same code with a 4-module white margin: decoded. On a mid-gray background, both versions decoded.

5. The destination URL is broken or not mobile-friendly

The number one reason a code 'does not work' is that the link behind it is dead, redirects in a loop, or loads a desktop-only page. Open the full URL in a phone browser first and confirm it loads fast over HTTPS.

6. Too much styling or logo coverage

Heavy artistic effects and oversized center logos can erase the data the scanner needs. If you add a logo, keep it well under 20 percent of the area (in our test, an H-level code stopped decoding above 19 percent) and use error correction level H to protect the pattern.

QR code at error correction level L with a square covering the center — Error correction L: decoded with up to 4% of the center covered.

QR code at error correction level H, 37 by 37 modules, with a larger square covering the center — Error correction H: decoded with up to 19% covered (Version 5, 37 x 37).

Try scannable artistic styles →

7. Your dynamic QR code expired

Many paid services issue dynamic QR codes that stop working when a trial ends or a plan lapses, even though the printed code looks fine. A static code has no such switch to flip. If a code suddenly died, this is the likely cause.

Replace an expired QR code →

8. Low print resolution or pixelation

Stretching a small image makes the modules blurry and unreadable. Download an SVG or a high-resolution PNG sized for the final print, and use the print size calculator to get the dimensions right.

Use the print size calculator →

9. Bad surface, lighting, or damage

Glossy, curved, or reflective surfaces scatter the camera's view, and creases or scratches break the pattern. Print on a matte, flat surface, keep the area well lit, and protect codes that will be handled often.

Confirm the fix before you reprint

After making changes, scan the code on both an iPhone and an Android phone from the real-world distance your audience will use. If it opens in a second or two on both, you are good to print.

Generating a fresh, high-contrast static code takes under a minute and rules out most of the issues above in one step.

Ready to build yours? Create a free QR code with Link2QR. No signup, no watermark, and no expiration.

Frequently Asked Questions

Why did my QR code work before and then stop?

The most common cause is an expired dynamic QR code from a paid service, where the redirect was switched off after a trial or plan ended. The second most common cause is that the destination page was moved or deleted. A static QR code avoids the first problem entirely.

What is the minimum size for a QR code?

About 2 cm (0.8 inches) per side for handheld scanning. Increase the size for anything viewed from a distance: keep the scanning distance to no more than 10 times the code's width.

Does adding a logo break a QR code?

It can if the logo is too large. Keep any center logo well under 20 percent of the code area (in our test, an H-level code stopped decoding above 19 percent) and use the highest error correction level (H) so the scanner can still recover the data.

Sources

Error correction feature, DENSO WAVE
Information capacity and versions of QR Code, DENSO WAVE

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