180 Percent Done

September 22, 2009 8:26 AM

Canonicalize this aphorism: "When you're 90% finished, you're half-way done."

Phrased otherwise, "First you do the first 90%, then you do the second 90%." I'm sure you've heard a similar expression. How was it phrased? I'm looking for the most widely recognized wording of the assertion that there's always far more work to be done than you estimate at the outset, preferably with a quotable source.

I'm aware of a Mythical Man Month reference, and I guess I want something a little more pithy.

posted by rlk to Writing & Language (12 answers total)

Sounds rather like the 80-20 rule: 20% of the work takes 80% of the time, or alternatively, 80% of the time is spent on 20% of the work. Wikipedia says this is called the Pareto Principal, but I think far more people will know what you're talking about if you say "80-20 rule"

From Mythical Man Month, I've always been fond of Brooks' line that (paraphrasing) "a baby takes nine months, no matter how many mothers are put to the task." Applicable to management and software threads.
posted by zachlipton at 8:30 AM on September 22, 2009

Yogi Berra said, "Baseball is 90% mental. The other half is physical."
posted by JohnnyGunn at 8:32 AM on September 22, 2009 [1 favorite]

I usually say something along the lines of, "we're done with the first 90%; it's the next 90% that's going to be hard."
posted by jeffamaphone at 8:38 AM on September 22, 2009

I've always heard it as "The first ninety percent of the task takes ninety percent of the time, and the last ten percent takes the other ninety percent." Googling for the source turned up a variety of attributions, so I'm not sure who came up with that particular phrasing.
posted by burnmp3s at 8:38 AM on September 22, 2009 [1 favorite]

For the record, burnmp3s's version is the one I've always heard.
posted by Johnny Assay at 8:48 AM on September 22, 2009

At work, we say "The last ten percent is half the project."
posted by rokusan at 8:55 AM on September 22, 2009

I've never heard this aphorism, but I've noticed the phenomena whenever I move out of a house. It's a quantification of Hofstadter's law.
posted by bendybendy at 8:56 AM on September 22, 2009 [2 favorites]

"Well begun is half done." -Mary Poppins
posted by birdwatcher at 10:33 AM on September 22, 2009

The usual way I've heard it stated is, "The first 90% of the work takes 90% of the time. The remaining 10% takes the other 90% of the time."
posted by Chocolate Pickle at 11:54 AM on September 22, 2009

I've always heard it as simply, "the last 10% takes 90% of the time"
posted by imaswinger at 1:12 PM on September 22, 2009

Writing the first 90 percent of a computer program takes 90 percent of the time. The remaining ten percent also takes 90 percent of the time and the final touches also take 90 percent of the time. ~N.J. Rubenking
posted by blue_beetle at 2:00 PM on September 22, 2009 [1 favorite]

In addition to those already mentioned, I've also heard it as an alternative usage for "the devil is in the details", meaning that even though the vast majority of the structure is done, most of the work is still to come, due to the detail work and polish being much more time consuming even though it's far less visible.
posted by -harlequin- at 3:43 PM on September 22, 2009