Calendar. Not to-do lists.

Viewing time as space.

Devi Parikh
7 min readApr 25, 2018

Good time management is one of the handful of factors that I attribute my professional accomplishments (to the extent that I have them) to. Several people have asked me for time management advice over the years. My understanding is that they’ve found the advice useful. With some encouragement from a subset of them, I figured that writing it down could increase the number of people that might find it useful. Hence this post.

What I say below is direct and prescriptive. I am only trying to be clear.

Goal: Be on top of things. Avoid drama and stress.

Assumption: Your bottleneck is time management, and not motivation.

Philosophy: Calendars convert time to space. They make the finiteness of time apparent. In a way that physical space constraints are apparent.

Basic Methodology

  • Make every task you would like to do — including meetings, “to-do’s”, doing nothing, watching Game of Thrones — a calendar entry.
  • Do the task at that time.
  • When done, move the task to a “done” calendar.
  • Go to bed with an empty “to do” calendar for the day. Either because you got everything done, or because you re-planned and moved pending tasks to other times of the week or month or year.

Principle 1: Everything takes time. So everything needs to be on your calendar.

  • Time is always ticking. When you are doing something, anything, including nothing, time is ticking. Which means, doing something, anything, including nothing, takes time.
  • There is finite time in the day. We are assuming you are motivated. So time is your bottleneck.
  • So the only effective way to plan is to make time central.
  • Lists are the wrong tool. They don’t make time central.
  • Calendars are the right tool. They make time central.
  • Everything you need to do — professional tasks, personal errands, recreational activities, meetings, meals, sleep, exercising, doing nothing, replying to email, planning a trip, planning to plan a trip, reading the news, thinking about a project, looking into the procedure in 2023 to renew your passport, reminding someone to do something, doing the thing you need to do before you can respond to an email, even marking calendar entries — needs to be an entry on your calendar. Because everything takes time.
  • Nothing is too small to be on your calendar. Everything takes time. Four “trivial” tasks can easily take up 30 minutes.
  • Bonus: An additional benefit of writing everything down is that nothing will get accidentally dropped.

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Principle 2: It is easier to measure how wrong your time estimates are than it is to fix them. Incorporate your calibration multiplier.

  • Most of us underestimate how long it will take to get something done. Some of us overestimate. I have never met anyone who gets it just right. What is your calibration multiplier?
  • Strive for a multiplier of 1.0. But that will take a while, and is hard.
  • Measuring the multiplier is much easier. Measure it. How long did you think something would take? How long did it actually take? Average it across multiple tasks.
  • When you put a task on your calendar, think about how long you think it will take. Then factor in the multiplier. Your gut instinct will tell you that the outcome is an overkill. It is not. By definition, the multiplier is telling you how wrong your gut tends to be. Don’t ignore the data.
  • This ensures that your plan for the day is a feasible one. You have (more accurately) estimated how long each task will take. And you have marked out corresponding chunks of time. You will only be able to fit as many things as 24 hours can feasibly hold. (Recall: sleep, meals, exercise are all tasks, also on your calendar). That makes your plan for the day feasible.
  • If everything you want to do in a day doesn’t fit, you need to prioritize. Don’t reduce your multiplier to make things fit. That is simply delusional.
  • Bonus: Recognizing a problem is a first step towards solving it. Measuring the multiplier will be a first step towards bringing it closer to 1.0.

Principle 3: More generally, incorporate your patterns.

  • If unexpected things tend to come your way in your job, mark some hours of your day every day as “buffer to deal with unexpected events” and don’t put tasks there.
  • If you are not a morning person, mark your mornings as “not a morning person” and don’t put tasks there.
  • If you see repeatedly that you are too tired on Saturdays to do anything, or don’t feel like doing anything, or your friends tend to make impromptu plans — plan for it. Don’t put anything on your calendar for Saturdays. Mark your entire Saturdays as “goof off”. Yes, officially plan to goof off.
  • More generally, work on any changes you’d like in your habits and temperament. But don’t plan around them till you have demonstrably established that you have changed. Be conservative when planning your days. Give yourself plenty of buffer. Staying on top of life is hard enough without mixing in other battles.

Principle 4: Re-plan.

  • The plan is feasible. But it is not guaranteed to work. Unexpected things will happen. Even with the multiplier, you may not get everything done as you planned. That is fine. Just re-plan.
  • Move things you could not get done to other open slots — tomorrow, later in the week, next week, whatever is feasible depending on the urgency of the task. If there is no open slot soon enough, something else from the future will need to move further out to make space for this task.
  • After re-planning, you once again have a feasible plan. Rinse and repeat.
  • A successful day is not when you get everything you planned to do that day done. It is one when you can go to bed with a feasible plan for every day ahead. Re-planning is not failure. Re-planning is part of the plan.
  • Some tasks if not done are more likely to cause stress and drama than others. Get those done first. So if something unexpected happens in the day, you are “safe”.
  • Bonus: You will soon start getting a high out of moving things from the “to do” to the “done” calendar. That will motivate you to get more done. To push a bit harder.
  • Pro-tip: If you happened to overestimate how long a task will take and you run out of tasks before your day ends, look ahead and consider getting a task from the future done. The future you will appreciate the extra buffer!

Principle 5: Break it down.

  • Tasks don’t always present themselves in calendar-sized chunks. A 300-hour project due in 3 months cannot be a calendar entry. Break it down.
  • Pro-tip: Planning for a large project — breaking it up into calendar-sized tasks, estimating how long each task will take, incorporating the multiplier, and marking them on your calendar in available slots — is a task. It takes time. So make planning the project a task on your calendar!

Principle 6: Backtrack. Foresee.

  • Backtrack on the timeline. A conference deadline is in 3 months. That means you need to start writing the paper at least a month before the deadline. That means you have a month to get your main basic result. Break each of these phases into calendar-sized tasks.
  • A week before the conference deadline tends to be crazy. Mark that entire week as busy. So as you plan other longer term tasks, you will avoid placing any tasks in that week. This will make sure the week before the deadline is not any more stressful than it needs to be.
  • If you can’t get tasks done when traveling, when family is visiting, etc. mark those days as busy.
  • This helps surface when things are more urgent than they might seem. Say a 6-hour job is due in 4 weeks. But you are at a conference all of next week, you have family visiting the week after that, and you have another major deadline at the end of the week after. This means you will not have time to work on this job in the next three weeks. This means the deadline for the 6-hour job is, for all practical purposes, in a week and not in four weeks. Your calendar will tell you all this — if you have been putting everything down on your calendar. As you try and put the 6-hour job on your calendar, there will “physically” be no space to put it in the next three weeks. And so you will have to put it down sometime in this week.
  • Backtracking tells you when is the latest you need to get something done. Don’t mistake it to be the time when you should do something. That gives you no buffer. Re-planning — whether because tasks are not done or because new tasks showed up — needs empty slots, needs buffer.

Principle 7: Visualize your time

  • Before going to bed every night, look at the calendar for the next day and internalize it. What kinds of tasks do you need to do? Is it more work related or more personal? Are there more meetings, or more desk time? Does the morning have many small tasks but the afternoon one larger task? This helps be in the right frame of mind to stay on top of your day.
  • Every Sunday, visualize your upcoming week. Is it front loaded or evenly spread? Make any adjustments to the placements of tasks as needed. Internalize the coarse layout of your week. This helps approach the week with the right frame of mind to stay on top of your week.


Example calendar: green = blocks, blue = meetings, orange= tasks.

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Devi Parikh

Research Director at Facebook AI Research. Associate Professor at Georgia Tech. Generative Artist. Artificial Intelligence.