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

A to-do list with 30 items does not tell you what to do at 9 a.m. It tells you what you will feel guilty about at 6 p.m. The 1-3-5 Rule fixes that by capping each day at nine items: one big task, three medium tasks and five small ones.

The cap only helps if you size the slots honestly. This guide covers where the rule came from, how long each tier should take, how to shrink it to 1-2-3 on meeting-heavy days, and what a good list looks like in four different jobs.

Where the 1-3-5 Rule comes from and why nine items works

The rule was popularized by Alex Cavoulacos, co-founder of The Muse, who described it as assuming you can accomplish one big thing, three medium things and five small things on any given day. Everything else waits for another day.

The mechanism is forced trade-offs. A list with only one big slot stops you from promising yourself three major deliverables before lunch. A list with fixed tiers also stops the opposite problem: a day made entirely of quick wins.

That second problem matters more than it sounds. Cavoulacos argues that small, reactive tasks like clearing email deliver a quick sense of reward, which is why they crowd out harder work. The rule does not ban busywork. It limits it to five slots and puts it beneath a single piece of work that actually moves something forward.

How to size the 1, the 3 and the 5

Most 1-3-5 lists fail at sizing, not at choosing. Use duration and mental load together: a task belongs in a tier because of how long it takes and how much uninterrupted thinking it needs.

Three sizing rules keep the tiers honest:

• A medium task that runs past 90 minutes is a big task. Promote it or split it.
• A small task that needs more than 15 minutes is medium. “Reply to the client” is small; “reply to the client with a revised scope” is not.
• The full list should fill about 5–6 hours, not 8. One big task (2.5 hours), three medium (about 2 hours) and five small (about 1 hour) leaves room for messages, breaks and the unexpected.

Pad your estimates on purpose. Research on the planning fallacy shows that people systematically underestimate how long their own tasks will take, even when they know similar tasks ran late before. If your big task usually overruns by an hour, budget the extra hour.

Building tomorrow’s list in ten minutes

Write the list at the end of the workday, when you still remember what is half-finished. Cavoulacos recommends the same timing, so the morning starts with the choices already made.

1. Pick the 1 first. Ask which single output would make tomorrow count if nothing else got done. Write it as a finishable result: “Draft sections 2 and 3 of the report,” not “Work on report.”
2. Check the calendar. Count your committed hours. If meetings take four hours or more, switch to the 1-2-3 version below.
3. Add three medium tasks that support current projects or deadlines this week.
4. Add five small tasks, preferring ones with a deadline or someone waiting on them.
5. Give the 1 a protected slot. Put it on the calendar, ideally in your first available two-hour block. If you want the full approach, see our guide to time blocking.

Here is how that looks for a mechanical engineer balancing CAD modeling, vendor RFQs and lab tests in a 7.5-hour day:

• 1: Finish the CAD model of the revised pump housing and run the interference check (2.5 hours).
• 3: Assemble the RFQ package for the machined bracket and send it to three vendors (45 minutes); review the data from yesterday’s thermal cycling run (40 minutes); update the procedure for Friday’s pressure test (30 minutes).
• 5: Approve one vendor quote; confirm Thursday’s lab booking; check the drawing files into the vault; answer a supplier’s tolerance question; order replacement strain gauges.

That totals about 5.4 hours, leaving roughly two hours of slack. If a vendor calls with a lead-time problem or a test rig fails, the day bends instead of breaking.

Meeting-heavy days: scale down to 1-2-3

The standard rule assumes most of your day is yours. The Muse’s own guide advises people who spend much of the day in meetings to scale the list down, and the simplest way is to drop to one big, two medium and three small tasks.

Do the arithmetic. An 8-hour day with 4.5 hours of meetings leaves 3.5 hours; subtract 30–45 minutes for transitions and messages and you have under 3 hours. A full 1-3-5 list needs 5 or more.

On a 1-2-3 day, shrink the big task to 60–90 minutes (“outline the proposal,” not “write it”), keep two medium tasks at 30–45 minutes, and limit small tasks to three. Do not count attending a meeting as a slot. Count the preparation or follow-up only when it is real work, such as writing the decision summary afterward.

Role-specific 1-3-5 examples

The tiers stay the same across jobs, but what fills them changes. Each row shows one example per tier; the last row is a meeting-heavy day on the 1-2-3 version.

The rule decides how much fits; it says little about order. Two other methods fill that gap:

• 1-3-5 sets the size of the day: nine items in three effort tiers.
• The Ivy Lee Method sets the sequence: six tasks ranked the night before and worked strictly top-down. That guide includes the full side-by-side comparison of all three methods.
• Brian Tracy’s Eat That Frog! sets only the first move: the hardest, most important task.

They combine well. Make your 1 the frog and do it first, which is the core of the Eat the Frog technique, then work the medium tasks in ranked order, Ivy Lee style.

When nine items don’t fit the day

• The 1 is a project, not a task. “Launch the website” cannot be finished today. Rewrite it as today’s output, and if you struggle to find that output, break the goal into steps first.
• The five small tasks eat the morning. Do the 1 before opening the inbox, then handle the small tasks in one or two sittings. Batching them keeps them from fragmenting the afternoon.
• The same big task rolls over three days running. It is either too large or being avoided. Split it, or move it to your first block of the day.
• Urgent requests keep arriving. Use a swap rule: a new item replaces one in its own tier rather than being added. If it outranks your 1, it becomes the 1 and the old one moves to tomorrow.
• You finish fewer than half the items most days. Log actual durations for a week and resize an overloaded list. If your big task routinely takes four hours, budget four.

Your evening 1-3-5 card

Paste this into a notes app or onto an index card and fill it in each evening:

• Free hours tomorrow: (total hours minus meetings). Under 3.5 hours? Use 1-2-3.
• 1 Big (2–3 h): one finishable output, with a calendar slot.
• 3 Medium (30–60 min each): tasks that support this week’s deadlines.
• 5 Small (under 15 min each): tasks with someone waiting or a due date.
• Total estimate: should land near 5–6 hours on a normal day.
• End-of-day check: Did the 1 get done? Move unfinished items to tomorrow or delete them.

Run it for two weeks before judging it. By then your estimates will be calibrated, and the list will reflect what your days can actually hold.