Capacity planning for service firms: a practical guide

Why firms overbook without noticing

Nobody decides to overbook their best person. It happens because commitments are invisible: the deadline lives in an email, the estimate lives in a proposal, the leave request lives in a chat, and the only place they meet is inside the manager's head. Every promise looks fine on its own. The pile is what breaks people, and no one is looking at the pile.

The arithmetic of real capacity

A person's real capacity is far smaller than their contracted hours, and pretending otherwise is where schedules start lying:

• Start with gross hours: the working day minus lunch.
• Subtract a daily reserve for meetings, email and admin. For most roles this is 20 to 30% of every single day, whether you plan for it or not.
• Hold back a buffer, a further 10 to 20%, so that revisions and surprises land in slack instead of in overtime. What remains is the planning target: the hours you can safely promise.

That final number surprises everyone the first time they compute it. It is why a team of five with "200 hours a week" on paper misses deadlines while apparently half-loaded: the paper number was never real.

The demand side: estimate in man-hours

Capacity planning only works when demand is written in the same currency. Every job needs a man-hour estimate, broken into steps, before it is promised. The estimates will be imperfect; that is what the buffer is for. A rough estimate against real capacity beats a perfect gut feeling every time.

The three failure modes that break schedules

• The sick-day cascade. One absence invalidates every plan that depended on that person, and nobody has time to replan the week by hand, so the plan silently dies.
• The quiet overload. Work flows to whoever says yes. Your most reliable person runs at 110% while a teammate sits at 60%, and by the time it is visible in morale it is expensive.
• The stale plan. A plan made Monday is fiction by Wednesday unless something updates it. Most firms update it never, or once a quarter in a painful all-hands reshuffle.

The ritual, or the software

The manual version of capacity planning is a weekly ritual: every Monday, list each person's available hours net of leave, place the committed work into them, and refuse new promises that do not fit. It works, and it costs a manager several hours a week that get skipped the moment things get busy, which is exactly when the plan matters most.

The software version does the same arithmetic continuously: it holds the reserve and buffer, places estimated work into real capacity, rebuilds the plan when something changes (we call that a reflow), and refuses to overbook a human being. The manager stops being the spreadsheet and goes back to being the manager.