Add one more person to your team and you are adding far more complexity than you realize. That person has to communicate with every person on the existing team, and communication lines mushroom with each additional body.
So adding one individual to a group of four means there are now 10 lines of communications, as everyone communicates with each other, compared to six beforehand. Add one extra employee to an eight-person team and communication lines jump from 28 to 36. Adding a newcomer to a 12-person team takes you from 66 to 78 lines of communication.
That's a lot of chances for things to go wrong. So it's where Jason Evanish, founder of Lighthouse , a software tool for managers, believes you need to stop. No manager should be directly supervising more than 12 people. Indeed, it's best to keep it down to eight to 10 people.
"Because you are a good manager for three or four people, doesn't mean you can handle seven or eight. I saw people who were crashing under the pressure of 12," Mr. Evanish said in an interview. "It doesn't matter the size of the company – it can be a startup or a larger company. That 12 team size crushes you."
As you add people, you gain more diversity and creativity. But it's extra bodies for a manager to keep track of when delegating tasks. It's additional personalities to handle. It's further people to coach and offer feedback. Like the frog in cold water that is put to the boil, it can be difficult to sense when the balance tips from acceptable to unacceptable. "Even good managers get stressed at nine or 10," Mr. Evanish said.
In a blog post, he noted other people had come to a similar conclusions.
Jeff Bezos, chief executive of Amazon.com Inc., has a rule of keeping meetings and teams to the number of people who can share two pizzas. If each person has two slices and the pizza has 8 slices, that means holding it at eight people so nobody goes hungry and the team doesn't choke on its own size.
Michael Lopp, author of the Rands in Repose blog, argues for seven, plus or minus three. So between four and 10. He figures if you spend half an hour weekly in a one-on-one with each direct report, seven will add up to 3.5 hours, half a day, a reasonable amount.
Tomasz Tunguz, a venture capitalist with RedPoint Ventures, concluded that seven is a good target when considering span of control and span of responsivity – how many subordinates a person can oversee.
As your team grows beyond a comfortable size, Mr. Evanish says you need to relinquish your desire for control. "One of the first things you have to do is accept you can't have first-level contact with everyone on your team any more. This can be scary if you're used to setting the standard and pace on your team, and worry that without direct influence that will change," he writes.
But while you can't serve the team in the same way you did, you can grow as a manager if you overcome your fears and need for control. You also need to begin thinking of two people from within your team who can be promoted to manager. He suggests two people because if you have grown to 12, the math works out well: Each of them can start modestly, overseeing four people, and you are also overseeing four (including them).
"The worst thing on Day 1 is to be thrown in the water with concrete boots. If, as a starting manager, you have seven to eight people, that's concrete boots," he says.
Adding two managers simultaneously also means your training can have double impact – instead of explaining to one person and then six months later explaining the same stuff to another person you have promoted, do it all at once.
The people you approach may not jump at the opportunity. Management is not for everyone. You may have to sell them on the advantages and then help them to accommodate to their new role. He suggests looking for people with empathy, attention to detail, organizational skills, and eagerness to learn. They should have in the past demonstrated leadership skills by taking charge of a group on a specific task.
"Just be mindful of people becoming managers for the wrong reasons, and choose who you promote wisely," he warns on the blog.
You aren't disappearing, initially. You are guiding them, and probably also holding skip-level meetings occasionally – perhaps once a month, perhaps once a quarter – with your former subordinates now reporting to them. But make sure those folks aren't coming to you instead of the new managers.
And make sure you are holding regular one-on-ones with the new managers to coach them. Don't leave them to sink or swim – without your assistance, they will indeed feel they are swimming with those concrete boots.
Over all, you have reduced the strain on yourself, strengthened the team, and multiplied your influence. Now keep an eye on those new managers, to make sure their team doesn't grow beyond a manageable size.
Harvey Schachter is a Kingston, Ont.-based writer specializing in management issues. He writes Monday Morning Manager and management book reviews for the print edition of Report on Business and an online work-life column, Balance. E-mail Harvey Schachter