Why You're So Bad at Estimating Time (And How to Get Better)
From optimism bias to calendar chaos: a guide to getting better.
The paperback version of Dreaming of the Office, Second Edition is now available, if you prefer a good old-fashioned book to pop on your desk (or in your ‘office in a bag’)! Happy reading.
Let’s be honest: most of us are terrible at estimating how long things will take. I certainly am. I tell myself I’ll finish this post in an hour. It’s always an hour. Why an hour? No idea. But here I am, 90 minutes in, and I’ve only just written the title.
If you’re trying to manage your time better—especially in a hybrid working setup—being able to realistically estimate how long tasks will take is fundamental. Without it, your carefully time-blocked calendar becomes a fantasy novel. Meetings run over. Emails swallow your morning. That ‘quick update to the slide deck’ eats your whole afternoon. Sound familiar?
So let’s take a deep dive into why estimating is so tricky, and how we can do better.
The Estimation Problem: Why We're So Optimistic
We all suffer from something psychologists call the planning fallacy—a lovely term for the completely human tendency to underestimate the time, cost, and effort needed to complete a task, even when we know similar tasks have taken longer in the past.
This happens for a few reasons:
We focus on best-case scenarios. You imagine the task going smoothly. You don’t account for interruptions, false starts, or the time it takes to find that email attachment you definitely downloaded last week.
We forget setup and wrap-up time. Writing a report doesn’t just mean writing the report. It means getting your notes in order, finding the right template, proofreading, exporting it to PDF, and emailing it off with a little explanation. That’s often as long as the task itself.
We confuse familiarity with speed. Just because you’ve done something a dozen times before doesn’t mean it’s fast. Repetition doesn’t always make you quicker—sometimes it just makes you assume you’ll be quicker.
We’re terrible at judging time in the moment. Ten minutes replying to that ‘quick email’ becomes forty. That one Teams message? It leads to an unexpected call. We forget how easily time melts away.
Hybrid Work Makes This Trickier
Hybrid working adds extra complexity. For one thing, the context-switching is more intense. I might start the day at home, pop out for a coffee meeting, then spend the afternoon in the office. Every change of location or work mode introduces friction—and friction costs time.
Plus, when you’re working remotely, it's easier to hide the fact that a task took longer than expected. There’s less external accountability. No one sees you procrastinate. You might get away with it—but your time plan won’t.
So What Can We Do?
Getting better at time estimation isn’t about perfection. It’s about becoming slightly less wrong, over time. Here are some strategies that have helped me (and that I recommend to anyone struggling with the same):
Track Your Time (Just for a Bit)
I resisted this for ages. But time tracking—even for a week—was a revelation. I used a simple stopwatch app and recorded how long I actually spent on each task. The results were humbling. That ‘quick reply to client’ was 25 minutes. The ‘bit of slide tweaking’ was an hour and a half.
You don’t have to do it forever. Just do enough to build intuition. Think of it like keeping a food diary: you get insight, not judgment.
Estimate in Ranges, Not Absolutes
Instead of saying, “This will take me 30 minutes,” say, “This will probably take between 30 and 45 minutes.” That’s much more realistic—and it gives you room for things to go wrong without blowing up your schedule.
If it’s a task you’ve never done before, widen the range. “Between 1 and 2 hours” is fine. You’ll get better at narrowing the range as you get more experience.
Break It Down Further Than You Think You Need To
Big, vague tasks like “write proposal” or “organise offsite” are estimation nightmares. Break them into small, concrete steps:
Draft outline
Get budget info from finance
Book meeting room
Chase feedback
Suddenly, the fog lifts. You can estimate each micro-task more easily—and even if you’re wrong about one bit, the damage is contained.
Always Add Buffer
I now pad every estimate with a buffer—usually 25–50% of the time I think it’ll take. This isn’t laziness; it’s realism. Things go wrong. You get interrupted. Your brain stalls.
If the task ends up taking less time? Great. You can use the bonus time to rest or get ahead. But if it runs over, you’re covered.
Use Past Data to Improve Future Estimates
Whenever a task overruns, I make a mental note—or a literal one in my task tracker. Why did it overrun? What threw me off? Over time, patterns emerge. I now know that:
Writing anything takes longer than I think.
Tasks involving other people (approvals, feedback, scheduling) always carry hidden delays.
Admin tasks feel small but often take ages because they span different systems.
Use your past mistakes to refine your future guesses. Think like a project manager: what were the risks? What can you plan around next time?
Create Time Templates
For recurring tasks, create time templates. For instance:
Weekly report: 45 mins writing, 15 mins formatting, 15 mins emailing
Client prep: 20 mins reviewing notes, 20 mins making deck, 10 mins setup
When you do a task regularly, don’t guess each time. Use a template and adjust as needed.
Use Deadlines Strategically
Deadlines help you estimate backwards. If something’s due Friday and you need an hour to do it, you know you need to carve that hour out—preferably before Thursday night…
Be honest about what will happen if you miss the deadline. Real urgency sharpens the mind. Fake urgency burns you out.
Watch Your Energy, Not Just Your Time
Some tasks take longer because we’re doing them at the wrong time of day. Writing, for me, is best in the morning. Admin? Mid-afternoon. Creative brainstorms? Not at 5:45pm when my brain is pudding.
So part of good estimation is knowing when you’ll be able to do a task well. That saves time in the long run.
Final Thought: Estimation is a Skill, Not a Guess
You can get better at it. It just takes feedback, reflection, and a bit of humility! The goal isn’t to become some robotic time oracle—it’s to stop overcommitting, underdelivering, and feeling guilty about the mismatch between your intentions and your output.
Once you’re estimating time more accurately, your calendar becomes a tool that actually works—not a source of stress. You’ll finish more of what you start, defer tasks before they derail your day, and go into meetings with just enough prep to shine.
And maybe, just maybe, you’ll finally write that post in under an hour.
(I didn’t. But hey—I'm getting closer.)