The 1-3-5 Rule: A Simple Way to Plan Your Day

Where did the 1-3-5 rule come from?

It has no single academic inventor. Its best-documented source is Betty Liu, who described the method in a 2019 interview with Business Insider while serving as executive vice chairman of the New York Stock Exchange: every morning she wrote down nine things to accomplish — one big, three medium, five small.

The idea sits on an older lineage. Ivy Lee’s 1918 advice to Charles Schwab was to write six tasks in priority order and work them in sequence; the MIT (Most Important Task) approach reduces the day to one to three priorities; Pareto’s 80/20 idea explains why a small number of items carry most of the value. The 1-3-5 rule is a practical blend: a hard cap like Ivy Lee’s list, a single priority like MIT, and a realistic spread of effort sizes.

What it adds to those methods is the shape of the day. A single most-important task ignores the twenty small things that keep a job running. A six-item list ignores that items differ wildly in size. Nine items in three sizes matches how knowledge work actually arrives.

Why does capping the list work better than a longer one?

Because the constraint attacks the two things that break daily plans: optimism about time and ambiguity about priority.

People underestimate their own task times, reliably. In the classic planning fallacy studies, Buehler, Griffin and Ross followed psychology honours students writing their theses. The students expected to finish in about 34 days on average; the typical actual completion was closer to 56. Their best-case estimates were optimistic, and even their worst-case estimates were closer to reality than their “realistic” ones.

Long lists hide the arithmetic. A fourteen-item list feels like a plan, but it is a wish with bullet points. If each item takes 45 minutes on average, fourteen items need 10.5 hours of uninterrupted work. No standard workday contains that, before meetings.

Written commitments get finished more often. The Zeigarnik effect describes how unfinished tasks stay active in memory and create mental load. Writing them into a bounded list externalises that load, and — more importantly — gives you permission to stop carrying the ones that were not chosen.

Choosing nine forces a real decision. With fourteen items, you can avoid deciding what matters because everything fits “somewhere”. With nine, two or three things must be explicitly dropped, deferred, or delegated. That moment of choice is the actual product of the method.

> Important note: the popular version of “decision fatigue” — that willpower depletes like a battery — has been questioned in replication work. The practical case for the 1-3-5 rule does not depend on it. It depends on arithmetic and on making the trade-off visible.

How do you size a big, medium, and small task?

Size by time and cognitive load, then check the total. The labels are not about importance; a small task can be urgent and a big task can be optional.

Two rules make the sizing usable in practice.

A big task must produce something you can point at. “Work on strategy” is not a big task; “draft the three-page strategy memo” is. If the output is vague, the task will expand to fill whatever time is available, which is Parkinson’s law operating on your calendar.

A small task must be genuinely small. The most common failure is smuggling medium work into the small slots. “Fix the onboarding email” sounds small until it involves three stakeholders and a copy review. If a small task will take more than 25 minutes, it is a medium task and the ratio is broken.

Example: does the arithmetic actually fit?

A team lead has a standard day: 8 hours at work, 1 hour of meetings, 45 minutes of email and chat in two batches, and 30 minutes of admin. That leaves about 5.75 hours of real working time.

• 1 big × 2.5 hours = 2.5
• 3 medium × 1 hour = 3.0
• 5 small × 0.25 hours = 1.25
• Total = 6.75 hours

The plan is one hour over capacity before anything goes wrong. Three fixes are honest: move two small tasks to tomorrow (6.25 hours), shorten the big task to 2 hours and drop one small (5.75 hours), or accept a 1-2-3 day and protect the big task. What does not work is keeping all nine and hoping.

Example: the monthly math

Twenty working days at nine items each is 180 commitments a month. A fourteen-item list, if you believed it, would be 280. The gap is not a productivity difference; it is a credibility difference. Teams that plan 180 items and finish 150 have a plan. Teams that plan 280 and finish 150 have a backlog and a nagging sense of failure, even though the output is identical.

How do you build tomorrow’s list in ten minutes?

Do it at the end of the working day, not in the morning. Evening planning uses the context you still have in your head and removes the morning decision about where to start.

1. Empty the inbox of commitments. Pull every open request from chat, email, and your task tool into one place. Do not filter yet.
2. Mark the one thing that would make tomorrow a good day. Not the most urgent item — the one whose completion changes something. That is your big task.
3. Choose three medium tasks that unblock other people or move a project forward. Prefer items that others are waiting on; they have a compounding effect.
4. Pick five small tasks that batch together. Admin, approvals, short replies, scheduling. Batching them into one or two windows protects the big block.
5. Do the arithmetic. Add the time boxes, add your meetings, and compare to your available hours. Cut or move items until it fits.
6. Write one sentence about the big task. “Draft sections 1–3 of the pricing memo, using last quarter’s data.” A precise first step is what turns a plan into a start.

That last step is not decoration. Implementation intentions — pre-deciding when, where, and how you will act — have a solid evidence base across dozens of studies, and the effect comes from removing the “how do I begin” hesitation at the moment of action.

What do you do when the day collapses anyway?

You rebuild the day rather than abandoning it. Interruptions, urgent requests, and a sick child are normal inputs, not evidence that planning is pointless.

Keep one unplanned hour. A 1-3-5 day that assumes zero surprises is a fantasy with better branding. Block 45–60 minutes as a rescue slot and treat whatever lands there as the day’s real work.

Use an explicit overflow rule. When something urgent arrives, decide which of three things happens: it replaces a small task, it replaces a medium task, or it goes to tomorrow’s list untouched. Deciding the rule in advance prevents the quiet slide where everything stays on today’s list and nothing gets finished.

Drop the ratio before dropping the big task. On a meeting-heavy day, run 1-2-3. On a day of back-to-back calls, run 1-1-2 and accept that the rest moves. The ratio is a tool; the single big task is the point.

Review at the end of the day in 90 seconds. What got done, what moved, and why. Three weeks of that review tells you whether your problem is over-planning, underestimating, or a job that genuinely has more demand than capacity — and only one of those is fixable with a better list.

Does the 1-3-5 rule work for teams?

Yes, with one change: the unit becomes the team’s outcome, not the individual’s task list. Used well, it becomes a lightweight way to limit work in progress without adding ceremony.

• Team standup: each person states their one big task, the three medium items, and what they will drop if something urgent arrives. Two minutes each, no status theatre.
• Shared big task: the team agrees on the single outcome the day is organised around. If five people each have a different “big thing”, the team has five priorities and no focus.
• Small-task batching: the five small items become a shared queue that anyone can pull from when blocked, which is a better use of a junior’s time than waiting for a meeting.
• WIP limits by implication: nine items per person is a natural cap. A board with 60 cards in progress across eight people is not busy; it is stalled.

For project work, pair the daily list with a weekly view so the big tasks trace back to a milestone. A daily list that is not connected to a plan produces nine completed items and a project that is still late. That is the same failure as a to-do list, just tidier.

How does it compare with other planning methods?

Most people end up with a hybrid: 1-3-5 for the daily list, time blocking for the big task, and a weekly review to keep the lists honest. That combination is more durable than any single method because each layer solves a different problem.

What are the trade-offs and limits?

It does not create capacity. If your job genuinely requires 11 hours of output a day, a nine-item list will not fix it. It will make the shortfall visible, which is useful but uncomfortable.

It can hide medium work. A project with eight substantial pieces does not fit into one big and three medium slots. In that case the rule needs a weekly horizon, not a daily one.

It rewards the wrong thing if you let it. Nine completed small tasks feel like a good day and produce very little. The test is whether the big task finished, not whether the list emptied.

It struggles with reactive roles. Support engineers, on-call staff, and account managers with a shared inbox cannot protect a three-hour block. For those roles, invert the ratio: one big task per week, and a daily list of five to seven small items.

> Common mistake: Treating an unplanned urgent request as proof that planning failed. Urgent work is part of the job. The failure is only when the plan had no room for it and no rule for what to drop.

Where does a tool help?

Paper works. A notebook and nine lines is a complete system, and nothing in this article requires software. Tools start to help when the list has to survive contact with other people: shared commitments, deadlines that move, and a week that has to reconcile with a plan.

That is the role Doitify plays for us. It is our project and team management platform, and it holds tasks and sub-tasks, checklists, owners and due dates, milestones, and workload views in one workspace, with recurring tasks and reminders so routine items do not consume planning attention. To be clear about the conflict: Doitify is our product, and if your work is entirely personal and simple, a notebook or a basic to-do app is a better fit than any platform. The value here is that the nine items on today’s list are the same objects your team sees, not a private copy that drifts by Wednesday.

Conclusion

The 1-3-5 rule works because it replaces an optimistic list with an honest one. One big task gives the day a centre, three medium tasks keep projects moving, and five small tasks absorb the operational work that never appears in a strategy deck.

The parts that matter most are the ones people skip: sizing tasks by time, doing the arithmetic against real available hours, and deciding in advance what gets dropped when something urgent arrives. Get those three right and the ratio can flex all it likes. Get them wrong and nine items become fourteen by lunchtime, which is exactly where you started.

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