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You know this one, even if you have never heard the name. The report is due Friday, so it takes until Friday. Give yourself a whole Saturday to clean the kitchen, and the kitchen takes all of Saturday. Give yourself twenty minutes, and somehow it is done in twenty.
About fifteen thousand people a month type what is Parkinson’s Law into a search bar. Most of them, I suspect, already know the answer from the inside. They want to know why it happens, and whether anything stops it.
Here is the honest version: where the idea came from (it is funnier than you think), why it is true, the famous study about it that just fell apart, and what actually helps.
What Is Parkinson’s Law?
Parkinson’s Law says: work expands so as to fill the time available for its completion.
The sentence comes from a short essay published in The Economist in November 1955. The author, Cyril Northcote Parkinson, was a naval historian, not a productivity coach. And he opened with a picture most of us recognise.
An elderly lady with nothing else to do, he wrote, can spend an entire day writing and posting one postcard. An hour finding the postcard. Another hour hunting for her glasses. Half an hour looking for the address. An hour and a quarter writing it. Then twenty minutes deciding whether to take an umbrella to the post box in the next street. A task that would take a busy person three minutes leaves her, in his words, “prostrate after a day of doubt, anxiety and toil.”
That is the law in one picture. The postcard did not need a day. The day was there, so the postcard took it.
If the day keeps taking everything you give it, and the tiredness has stopped lifting, it is worth a quick, honest check. Our free Am I Burned Out at Work? test takes about two minutes.
The Law Was Never About You
Here is the part almost every article on Parkinson’s Law skips. The postcard lady was only the warm-up. The essay was not about personal time management at all. It was a straight-faced joke about government offices that keep growing no matter how little they have to do.
Parkinson laid out his numbers like a scientist. Between 1914 and 1928 the Royal Navy’s big warships fell from 62 to 20, and its sailors from about 146,000 to about 100,000. In the same years, the number of officials running the Navy from desks rose from 2,000 to 3,569. A smaller navy, a much bigger office.
Then the Colonial Office. Its staff went from 372 people in 1935 to 1,661 in 1954, while the empire it was supposed to administer was shrinking year by year as colonies became independent.
He offered two reasons, worded like laws of physics:
- “An official wants to multiply subordinates, not rivals.” An overworked manager never asks for one equal to share the load. He asks for two juniors, so he stays the only person who understands both halves.
- “Officials make work for each other.” Seven people now pass a single letter around, and the boss ends up writing the same reply he would have written alone, only later in the evening.
He even closed with a mathematical formula for how fast any department will grow. It was a parody, and the formula was nonsense on purpose. But people loved it so much that it became a book in 1957, Parkinson’s Law: The Pursuit of Progress, which also gave us the “law of triviality”: a committee will spend the most time on the smallest item on the agenda.
So why does everyone now use Parkinson’s Law to mean “I waste time when I have time”? Because the first sentence was simply too true to stay in the office. It travelled. A later version, often called the Stock-Sanford corollary, puts it bluntly: if you wait until the last minute, it only takes a minute to do.
Why Work Expands to Fill the Time
Parkinson gave the pattern a name. He did not really explain it. Here is what seems to be going on underneath.
You guess wrong about how long things take
In 1994, three psychologists, Roger Buehler, Dale Griffin and Michael Ross, asked 37 students finishing an honours thesis to predict their completion date. The students’ best guess averaged about 34 days. The real average was about 55. Fewer than a third finished by the day they had named, and even their own “worst case” guesses came in about a week short of reality. Researchers call this the planning fallacy, and it shows up in task after task.
Notice how that interacts with Parkinson. If you misjudge the work, you give it a loose, generous block of time “to be safe.” Then the loose block fills up, and the work still runs late. Both laws win at once.
Open time invites “while I’m at it”
Look again at the postcard. Not one of those five steps was the postcard. Finding glasses, debating an umbrella: each one was a small side decision that only existed because there was room for it. When a task has no edges, every neighbouring task leaks in. If you have ever lost an afternoon to the “while I’m here” version of a job, you have met this. The umbrella question is also a tiny case of analysis paralysis: a decision that could not matter, given a stage to perform on.
“Done” was never defined
Most tasks have a point at which they are good enough. If you never name that point, the task does not know when to stop, so it uses the clock as its stop instead. Time becomes the only finish line, and it is a bad one.
The Famous Deadline Study That Fell Apart
For twenty years, almost every explainer about Parkinson’s Law reached for the same piece of evidence. In 2002 two researchers, Dan Ariely and Klaus Wertenbroch, published a study in the journal Psychological Science. Sixty people proofread texts under three kinds of deadline: one final deadline, deadlines they set themselves, or deadlines spaced evenly by the experimenters. The group given evenly spaced deadlines did dramatically better. The lesson travelled everywhere: impose tight, regular deadlines and Parkinson’s Law loses.
That study is now in serious trouble. In 2026, economists Kyle Hyndman and Alberto Bisin published a replication in the same journal and found the deadline structure made almost no difference to performance. Separately, the authors of the data-forensics blog Data Colada examined the original data and reported several red flags, including an effect size they described as larger than the height difference between men and women, and eighteen of the twenty people in one group having an exact “twin” with identical scores. Their conclusion, in their words, was that the data were “severely tampered with or fabricated.”
Two things are worth holding at once here. First, the lived experience behind Parkinson’s Law is real; you do not need a study to know the postcard took all day. Second, the tidy promise that strict external deadlines fix it was resting on evidence that no longer stands. Deadlines help some people some of the time. They are not a law of nature. Whatever you build to beat Parkinson’s Law has to work for you, not for a chart.
How to Use Parkinson’s Law Instead of Losing to It
None of this needs an app, money, or a free weekend. It works on a kitchen table.
- Define “done” before you start. One sentence. “Done means the postcard is in the box.” If a step is not in the sentence, it is not the task.
- Give the task a box, not a day. Set a specific, slightly uncomfortable length of time, then stop when it ends. If the work is not finished, you have learned something true about the work, which is worth more than a guess.
- Make the stop point to something. A box with nothing after it is easy to ignore. A box that ends at a walk, a meal, or a person you have promised to see holds its shape.
- Cut the box in half once. Try it on one small job this week. Most people find the half-sized version produces nearly the same result, which tells you how much of the old block was filler.
- Catch “while I’m at it” out loud. When the umbrella question appears, say the phrase. Naming it is usually enough to put it down.
If any of this feels impossible because there is never a stop at all, that is a different problem, and a bigger one. We have written about what happens when more hours stop producing more work in What Is Hustle Culture?
The Oldest Deadline on Record
There is a strange footnote to all of this. Parkinson was not the first to notice that work takes whatever time it is given. One of the oldest sets of rules people still live by says it the other way round.
The Ten Commandments include a line about work that most people read as a rule about a day off. Look at it as time management and it reads differently: “Six days shalt thou labour, and do all thy work.” All of it. In six. The command does not say “work until you are finished and then rest if there is time.” It sets the stop first, then tells the work to fit inside it. The seventh day is not stolen from the to-do list. It is the edge of the box, and the edge is what makes the work finish and the worker stop.
The idea underneath is quietly radical, and it is older than any office. Rest was not something to be earned once everything was done. It was given first, by God, as the shape of the week, and the work was expected to arrange itself around it. Parkinson found the same truth from the other side, in a navy that grew while its ships disappeared. Work fills what you give it. So the deciding act is not the working. It is choosing where the edge goes.
A good place to start:
Why Your Mind Won’t Slow Down at Night (Free)
A short guide to why the day keeps running after you have stopped, and the 5-step order that lets your mind finally settle.
Free.
Where the Edge Goes
Back to the postcard. The lady was not lazy. She was busy all day, and she went to bed exhausted. That is the cruel part of Parkinson’s Law: it does not feel like wasting time. It feels like working.
You cannot make the postcard take three minutes by trying harder. You can only decide, before you pick up the pen, when you are putting it down. Pick the edge. Put something good on the other side of it. Then let the work be as big as the box, and no bigger.
Questions People Ask About Parkinson’s Law
What is Parkinson’s Law in simple terms?
Parkinson’s Law is the observation that work expands to fill the time available for its completion. If a task is given a week, it tends to take a week; if the same task is given an afternoon, it often gets done in an afternoon. The phrase comes from an essay by the naval historian Cyril Northcote Parkinson, published in The Economist in November 1955.
Who came up with Parkinson’s Law?
Parkinson’s Law was coined by Cyril Northcote Parkinson, a British naval historian, in a satirical essay published in The Economist in November 1955. The essay was mainly about how government departments grow regardless of workload, using the British Admiralty and Colonial Office as examples. It became a book, Parkinson’s Law: The Pursuit of Progress, in 1957.
Is Parkinson’s Law scientifically proven?
Parkinson’s Law is a widely observed pattern rather than a proven scientific law. The original 1955 essay was satire, and its formula was a joke. The most-cited supporting study, a 2002 deadlines experiment by Dan Ariely and Klaus Wertenbroch, failed to replicate in 2026, and the data-forensics blog Data Colada concluded its original data appeared tampered with or fabricated. Related research on the planning fallacy, which shows people routinely underestimate how long tasks take, is better supported.
How do you beat Parkinson’s Law?
To beat Parkinson’s Law, define what “done” means before starting, give the task a fixed and slightly tight block of time instead of an open day, and place something concrete at the end of the block such as a walk, a meal or a meeting. Cutting a planned time block in half on a small task shows how much of the original estimate was filler. Naming side tasks out loud as they appear helps stop them leaking into the main job.
What is the Stock-Sanford corollary to Parkinson’s Law?
The Stock-Sanford corollary is a later, informal restatement of Parkinson’s Law that says: “If you wait until the last minute, it only takes a minute to do.” It captures the personal time-management reading of the law, which is now far more common than Parkinson’s original point about the growth of bureaucracies.
Discussion Question
Do you think deadlines genuinely make people work better, or do they just move the stress to the last day? Tell us in the comments. We would genuinely like to hear your take.
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Post 1: Parkinson’s Law was never about productivity. It was a joke about a navy whose warships fell from 62 to 20 while its office staff nearly doubled. Good read: https://bgodinspired.com/index.php/real-life/what-is-parkinsons-law/
Post 2: The famous “evenly spaced deadlines” study that everyone cites for Parkinson’s Law just failed to replicate, and the original data look tampered with. Changed how I think about deadlines: https://bgodinspired.com/index.php/real-life/what-is-parkinsons-law/
Post 3: “The postcard did not need a day. The day was there, so the postcard took it.” Felt that. https://bgodinspired.com/index.php/real-life/what-is-parkinsons-law/
