Laws of UX
Miller's Law
Working memory holds only a handful of items — chunk information to ease the load.
Where it comes from
It comes from a celebrated 1956 paper by the cognitive psychologist George Miller, 'The Magical Number Seven, Plus or Minus Two', one of the founding documents of cognitive psychology. The catchy number stuck; the more careful lesson about chunking is the part designers should keep.
Why it matters for your website
The brain holds only a few things in working memory at once. Miller's Law says information broken into manageable chunks is processed faster and remembered better. Long, unstructured lists overwhelm visitors and push them toward the exit. (Note: the famous "7±2" is often overstated — the lesson is chunk, not a hard number.)
The number itself has been steadily revised downward — later research suggests working memory holds closer to four items than seven — but arguing about the figure misses the point. What matters is that the limit is small, and that chunking expands it: a phone number is far easier to hold as three groups than as ten loose digits, even though the information is identical.
On a page, this is the difference between a long undifferentiated list and the same content grouped into labelled sections. The grouping doesn't reduce how much there is; it reduces how much the visitor has to hold at once to make sense of it — which is what keeps a complex page feeling navigable rather than overwhelming.
Wrong vs right
A navigation menu of 15 ungrouped links in a single column, asking the eye to hold the whole set in mind to find one item.
The same 15 links sorted into four labelled groups, so the visitor scans the four headings first and only then the handful beneath the right one.
A 16-digit account number displayed as one unbroken string, easy to misread and impossible to hold in memory.
The same number broken into four groups of four — easier to read, verify, and remember.
A settings page listing 30 options flat, with no sections, so the user has to scan all of them to find anything.
Options grouped under clear category headings, turning one impossible scan into a quick two-step one.
Understanding Miller's Law
Miller's Law is about the narrow bottleneck of working memory — the small set of things a person can actively hold in mind at one moment. Miller's original figure was 'seven, plus or minus two', though modern estimates are lower and the exact number depends on the material. For design, the precise figure matters far less than the principle: working memory is limited, and you should design so users rarely have to lean on it.
The lever the law hands you is chunking — grouping individual items into larger, meaningful units. A chunk counts as roughly one item against the limit, so organising content into a few well-labelled groups lets people handle far more total information than a flat list of the same length. This is why grouped navigation, sectioned forms, and formatted numbers all feel easier: they shrink the count of things to track.
It's worth being clear that Miller's Law is not a rule that pages should contain at most seven things. It's an argument for structure, not scarcity: you can present a great deal, as long as it's chunked so the visitor only ever holds a few groups in mind at once. It sits alongside chunking and cognitive-load theory in the family of ideas about not overloading the mind.
How Kweri checks it
Kweri assesses this structurally — it looks at whether long sets of items (navigation, lists, form fields, options) are broken into labelled groups, or presented as one undifferentiated run. It can reliably flag flat, ungrouped collections that are likely to tax working memory. What it can't measure is the *meaning* of your grouping — whether the chunks you've chosen are the ones that make sense to your audience. So Kweri catches the absence of chunking and prompts you to group, while leaving the judgement of which groupings are right to you.
FAQ
What is Miller's Law?
Miller's Law observes that the average person can hold only a small number of items — Miller's original estimate was seven plus or minus two — in working memory at once. In design it's used to argue for chunking information into small, meaningful groups.
Is the '7 plus or minus 2' rule accurate?
It's widely considered overstated. Later research puts working-memory capacity closer to four items, and the figure varies with the type of information. The durable lesson isn't the exact number — it's that the limit is small and chunking helps.
What is chunking?
Chunking is grouping individual pieces of information into larger, meaningful units — like reading a phone number as a few groups rather than ten separate digits. Each chunk counts as roughly one item in memory, so chunking lets people handle more overall.
Does Miller's Law mean menus should have 7 items or fewer?
Not literally. It's not a hard cap; it's an argument for structure. You can present many items as long as they're chunked into a few labelled groups, so the user only holds a handful of groups in mind at a time.
How is Miller's Law different from Hick's Law?
Miller's Law is about how much you can hold in working memory; Hick's Law is about how long it takes to decide between options. Both push toward grouping and structure, but one concerns memory and the other concerns decision time.
Related principles
Breaking information into small, meaningful groups makes it faster to scan, understand, and remember.
The brain has a limited processing budget — demand too much and performance collapses.
The brain's temporary active store holds only 4–7 chunks for 20–30 seconds — information users have to remember across steps will be forgotten unless the system carries it for them.
Attribution & sources
Identified by George A. Miller (1956). Catalogued from Laws of UX (Jon Yablonski).
From Miller's 1956 paper 'The Magical Number Seven, Plus or Minus Two'; popularised for designers by Jon Yablonski's Laws of UX.
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