Every QR code carries more data than it strictly needs. The surplus is error correction — redundant information woven through the pattern so a scanner can rebuild whatever it cannot read. It is why a code still works with a coffee ring on it, a crease through the middle, or a logo in the centre.
You choose how much surplus to build in, and there are four settings.
The four levels
| Level | Recovers | Feels like | Good for |
|---|---|---|---|
| L | about 7% | Sparse, easiest to scan at distance | On-screen codes, slides, anything short-lived |
| M | about 15% | The sensible default | Flyers, menus, most printed work |
| Q | about 25% | Noticeably denser | Codes that get handled, stickers, labels |
| H | about 30% | Densest | Outdoor signs, laminated menus, codes with logos |
Higher is not automatically better
This is the part that surprises people. Error correction is not free — the redundant data has to go somewhere, so raising the level either fills up the space you had or pushes the code to a larger version with more, smaller squares.
Smaller squares are harder to resolve. A dense code needs a better camera, more light, or a closer scan than a sparse one. So you can absolutely make a code less reliable by giving it more error correction, if the extra density costs you more than the redundancy buys.
The trade-off in one sentence: error correction protects against damage, low density protects against bad scanning conditions. Pick for whichever threat is real.
What we default to
Leave the level on Automatic and our generator uses M for a plain code and switches to H the moment you add a logo — because a logo eats directly into the recovery budget and H is what makes that safe.
That default is right for the large majority of jobs. Change it deliberately, not out of caution.
When to raise it by hand
- Outdoor signage. Sun, rain and dust degrade a printed surface over months.
- Laminated or handled items. Menus, loyalty cards, anything that lives in a pocket.
- Industrial or dirty environments. Warehouse labels, equipment tags.
- Codes you cannot easily reprint. Engraved, embroidered, moulded into a product.
When to lower it
- On-screen only. A code in a slide deck or a video overlay takes no damage at all, and L keeps the pattern sparse enough to scan from the back of a room.
- Very small print with a short link. Sometimes the sparser pattern is what makes it readable at all.
Logos change the maths
If you are putting a logo in the middle, the level sets your ceiling directly. At H you can safely cover about 25% of the width; at M that drops to around 17%; at L to about 12%. Our generator warns you when the logo passes the safe threshold for the level you are on — the full explanation is in the logo guide.
Note that those ceilings sit well below the recovery percentage. That gap is deliberate: it is what is left over to survive the real world after the logo has taken its share.
The simple rule
If nothing is going to damage or cover the code, M is fine and you should stop thinking about it. If it will be printed, handled and left outdoors for months, go to Q or H. If it has a logo, leave it on Automatic and let it pick H.
Then test it at the size and on the material it will actually live on — that tells you more than any table.