Capacity planning, read as an account
Most plans fail as arithmetic long before they fail as prediction.
Fifty notes on capacity planning and resource allocation, written as a reconciliation rather than a forecast. Two sides — what exists and what has already been promised — counted in different units, over different periods, by people who never compare the two.
Gross to net for one team quarter, as the planner worked it
Starting point: 13 weeks at 40 hours.
Booked and forecast together.
Fixed and known a year ahead.
A rate, not a prediction about anybody.
Booked centrally; the plan rarely sees it.
Measured once, for one quarter, never since.
Sixty-six per cent of contracted hours.
A third of the contracted hours never reach planned work, and the only line anybody had estimated was the first one. Every deduction here is ordinary and none of them is optional. This is one employer's own quarter, not a benchmark.
No organisation is told what its method should be. Every figure here is an illustration of what one employer recorded for itself, labelled as such. Nothing in this collection is financial, legal or contractual advice: what may be committed, on what terms and with what notice differ by jurisdiction, by sector and by agreement, they change, and they are a question for somebody qualified in the place concerned.
The two tables that decide a plan
One quarter of one team, counted by both sides
Both sides believe they are planning the same quarter, and the difference between their arithmetic is a person and a half. Neither number is wrong; they are answers to different questions that nobody wrote down. This is one employer's own reconciliation, not a benchmark.
Claims on one team's next quarter, as found in six places
Signed off in March, with dates.
Recurs every quarter; nobody re-books it.
Decision deferred twice; still in the plan.
No number, no dates, repeated three times since.
Measured once, in a quarter nobody remembers.
Closed in January; still in two spreadsheets.
Six claims on a team of four. Two are confirmed and come to 2.0 FTE, one is provisional at 1.0, two rest on nothing at all and one is for work that finished in January. Added up, the book already exceeds the team, and no single document anywhere says so.
The reconciliation in “Most plans fail as arithmetic long before they fail as prediction.” is strongest when assumptions and current work records can be examined separately. A team considering employee monitoring software for employee monitoring software can add time and project context, with transparent settings, limited access and a clear correction route around consequential decisions.
For an outside reference relevant to “Most plans fail as arithmetic long before they fail as prediction.”, consult GAO strategic-planning resources. Compare the general guidance with the organisation’s own unit, period and decision rights.
Why this is an accounting problem
Almost everything written about capacity planning is about forecasting: how to predict demand, which curve to fit, how far ahead to look. That is a real problem and it is rarely the one that breaks a plan. Plans break earlier, in arithmetic, and they break in a way that is visible on the day they are published rather than three months later.
The arithmetic has two sides. One side is what the organisation actually has: people, hours, machines, rooms, licences — net of leave, training, support, interrupts and everything else that comes off before anybody does planned work. The other side is what has already been promised: projects signed off, work pencilled in, standing commitments nobody re-books, and the long tail of claims that exist only in an email from a sponsor.
Neither side is usually written down in full, and the two are expressed in different units over different periods by people who do not read each other's documents. So the subtraction never happens. The result is a plan that was impossible when it was published, and an organisation that experiences the impossibility as a series of individual overruns.
The sections follow the account: what a unit is, what you actually have, what is already promised, where the two sides disagree, how to close the books, what to do when the answer is negative, and what the variance teaches the next plan.
01 / 07
The unit
What one unit of capacity actually is, and why every plan silently mixes several of them.
02 / 07
What you actually have
The descent from contracted hours to hours available for planned work, line by line.
03 / 07
What is already promised
The book of claims on capacity — confirmed, provisional, assumed and long expired.
04 / 07
Where the two sides disagree
Different units, different periods, different owners — and the difference nobody computes.
05 / 07
Closing the books
The reconciliation itself: who performs it, how often, against what evidence, and what it has to balance.
06 / 07
When there is not enough
Allocation under shortage — priority, partial allocation, saying no, and who is allowed to decide.
Capacity software
Tools for capacity reconciliation and workforce planning
Three different comparison formats based on structured product review and repeatable forecasting checks.
07 / 07
What the variance teaches
Plan against actual, where the error actually was, and how the next plan changes because of it.
The short version
Do the subtraction before making the promise
A capacity plan is not a prediction about the future. It is a subtraction: what exists, less what has already been promised, in one unit and one period. Most organisations never perform it, because the two sides live in different documents owned by different people and expressed in different units. The subtraction takes an afternoon. The plan that follows it is not better at forecasting; it is simply possible, which the previous one was not.