How is the 5+50+100 rule different from Dunbar's number?

Dunbar's number is descriptive science: research suggesting human social capacity tops out around 150 meaningful relationships, layered roughly 5/15/50/150. The 5+50+100 rule is prescriptive method: Judy Robinett's system for deliberately curating 155 strategic relationships with set contact rhythms. The rule borrows the science's ceiling and layer logic but chooses membership strategically and skips the 15 layer.

Who belongs in the Top 5?

Robinett's bar is high: people whose judgment you trust completely, who know your goals, who would act for you without being asked — mentors, key partners, your closest advisors. The test is mutual: you would do the same for them. It is explicitly not 'the five most powerful people you know'; a Top 5 without deep reciprocal trust is just a wish list.

Is contacting 155 people on a schedule realistic?

At Robinett's full cadence — Top 5 daily, Key 50 weekly, Vital 100 monthly — only with serious discipline and tooling; she wrote the book for professional connectors. A softened version (weekly / monthly / quarterly) totals roughly 8–10 meaningful touches per week, which most people can sustain in under an hour — provided something tracks who is due, because memory alone reliably fails at this scale.

Network science

5+50+100 rule

The 5+50+100 rule is Judy Robinett's networking method: curate a Top 5, a Key 50 and a Vital 100, each circle with its own regular contact rhythm.

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The 5+50+100 rule is a system for running a 155-person strategic network, introduced by Judy Robinett in her 2014 book 'How to Be a Power Connector: The 5+50+100 Rule for Turning Your Business Network into Profits' (McGraw-Hill). Instead of accumulating contacts indefinitely, you curate three concentric 'power circles': a Top 5 of your most critical relationships, a Key 50 of important strategic ties, and a Vital 100 of valuable contacts you want to keep genuinely warm.

Each circle carries a contact cadence. Robinett's prescription is demanding: connect with your Top 5 essentially daily, your Key 50 weekly, and your Vital 100 at least monthly. The deeper move, though, is the curation itself — deciding who belongs in which circle, pruning as life changes, and accepting that anyone not in the 155 gets opportunistic rather than scheduled attention.

The rule is a practitioner's heuristic, not a peer-reviewed finding, but it deliberately rhymes with the science: Robinett grounds her numbers in the research tradition around group-size limits, and the 155 total sits almost exactly on Dunbar's number, while the inner circles echo the 5 / 15 / 50 layers documented in Robin Dunbar's work.

How the method works in Robinett's telling

Robinett — profiled in business media as 'the woman with the titanium digital Rolodex' — built the method on decades as an entrepreneur, CEO and startup investor. The mechanics: inventory everyone you know; score relationships by strategic value and mutual trust, not affection alone; assign the Top 5 (people whose judgment you'd bet on and who would take your call at midnight), the Key 50 (decision-makers, connectors and domain experts across the 'ecosystems' that matter to your goals — she emphasizes spreading them across distinct industries and communities rather than one), and the Vital 100. Then work the cadences, always leading with value: introductions, information, opportunities flow from you first. Two design choices distinguish the system from generic networking advice. First, the hard cap — 155 forces triage, which is what most networks lack. Second, ecosystem diversity in the Key 50, which quietly imports the bridging logic of weak-tie and structural-holes research into a practical checklist.

How it maps onto Dunbar's layers — and where it differs

The resemblance to the science is close but not exact. Research by Robin Dunbar and colleagues describes natural network layers of about 5, 15, 50 and 150, each roughly three times the last (Zhou, Sornette, Hill and Dunbar, Proceedings of the Royal Society B, 2005); the layers reflect how finite social time gets distributed, and they describe whole personal networks including family. Robinett's circles are 5, 50 and 100 — she skips the 15 layer, her numbers are cumulative targets for a deliberately professional network, and membership is chosen by strategy rather than emerging from emotional closeness. The cadences also run hotter than observed behavior: Dunbar-tradition studies find the typical 50-layer contact happens about monthly, not weekly. None of this is a flaw, exactly — Robinett is prescribing effort above baseline, and the baseline research explains why her cap works: a curated 155 sits at the edge of what human social cognition maintains meaningfully. But it is worth knowing which parts are evidence (the layered structure, the ~150 ceiling, time as the binding constraint) and which are method (the specific 5/50/100 split and the daily/weekly/monthly drumbeat).

Running your own 5+50+100 (without burning out)

A sustainable adaptation keeps the curation and softens the cadence. Start by actually writing the three lists — most people have never once enumerated their network, and the exercise alone reveals misallocated attention. Choose rhythms you will keep: weekly-ish for the 5, monthly for the 50, quarterly for the 100 is ambitious enough for anyone with a job and a family. Make each touch genuine — a question, a relevant link, a congratulation tied to something real — because rhythm without substance reads as automation. And review the lists quarterly: circles are positions, not life appointments. The bookkeeping is the part that defeats spreadsheet attempts, and it is precisely what Endearist automates: priority tiers mirror the circles, each tier gets its own keep-in-touch interval, and the app surfaces who is due — while the Dunbar calculator on this site gives you a research-grounded first pass at sorting your people into layers.

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Frequently asked questions

How is the 5+50+100 rule different from Dunbar's number?: Dunbar's number is descriptive science: research suggesting human social capacity tops out around 150 meaningful relationships, layered roughly 5/15/50/150. The 5+50+100 rule is prescriptive method: Judy Robinett's system for deliberately curating 155 strategic relationships with set contact rhythms. The rule borrows the science's ceiling and layer logic but chooses membership strategically and skips the 15 layer.
Who belongs in the Top 5?: Robinett's bar is high: people whose judgment you trust completely, who know your goals, who would act for you without being asked — mentors, key partners, your closest advisors. The test is mutual: you would do the same for them. It is explicitly not 'the five most powerful people you know'; a Top 5 without deep reciprocal trust is just a wish list.
Is contacting 155 people on a schedule realistic?: At Robinett's full cadence — Top 5 daily, Key 50 weekly, Vital 100 monthly — only with serious discipline and tooling; she wrote the book for professional connectors. A softened version (weekly / monthly / quarterly) totals roughly 8–10 meaningful touches per week, which most people can sustain in under an hour — provided something tracks who is due, because memory alone reliably fails at this scale.

Sources

Last updated: 2026-06-10

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