Project Timeline Calculator
Effort divided by capacity — the working days a crew needs, the finish date on the five-day week, and the linear model's caveat named.
Project Timeline Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Linear model — no ramp-up or communication cost
- Weekends only skipped — no holiday calendar
In short: 1,200 person-hours at 6 people × 8 h a day is 25 working days — started Monday, 21 September 2026, the crew finishes Friday, 23 October 2026, with 33 calendar days and 8 weekend days inside. The model is deliberately linear: effort ÷ capacity, walked down the five-day week. Brooks's law is quoted in the caveat card for exactly the reason the arithmetic cannot see ramp-up or communication — the page prices the plan you typed, not the friction teams add.
Formula
working days = ⌈effort ÷ (crew × hours)⌉, walked down the five-day week
Effort and duration are different quantities: effort is person-hours of work, duration is the calendar the crew converts it into. The page divides one by the other, rounds up to the whole day a plan can actually start, and walks the result down a week that skips Saturdays and Sundays — no holiday calendar is modeled, stated here. The linearity is the model's honest limit: doubling the crew halves the division, and real teams know better.
Worked Example
- Enter the start date, the effort and the crew.
- Read the working days and the finish date.
- Weigh the caveat — the model is linear.
Defaults: 1,200 person-hours at 6 × 8 lands Friday, 23 October 2026 — 25 working days, 33 calendar, 8 weekend days inside.
Strengths & Limits Of This Model
Where this engine is strong
- Finish date on the stated five-day week
- Effort vs duration named as different quantities
Where it stops
- One crew, one rate of work per run
Practical Use Cases
Scoping
effort into a finish date a client reads
Staffing
what a second pair of hands actually buys
Bids
the five-day week, walked honestly
Methodology & Editorial Standards
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Project Timeline Calculator — 8 Expert FAQs
8 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
Why does the page round up to whole days?
A plan starts in the morning, not at 12.5. The division 1,200 ÷ 48 is exactly 25 here, but 96 person-hours a day over 1,200 reads 12.5 — and a half-day finish is a finish on the 13th day. The grid deals in days the crew can book.
What is Brooks's law doing on this page?
Naming the model's limit. Fred Brooks put it in 1975: “adding manpower to a late software project makes it later.” The division here is linear and knows nothing of ramp-up, communication or the tasks that refuse to split — the caveat card says so rather than letting the clean arithmetic pose as a promise.
Are holidays counted?
No — the walk skips Saturdays and Sundays only. Holiday calendars are jurisdictional and firm-specific; the page states the convention instead of pretending one, and the finish date is exact on that stated five-day week.
How far out can the finish land?
As far as the effort demands — 50,000 person-hours at 25 × 8 walks 250 working days into September 2027. The date arithmetic is exact across years and leap days; the only fiction is the weekend holiday-free week, already named.
Why person-hours instead of tasks?
Tasks differ by orders of magnitude; person-hours add. The page takes the estimate your plan already speaks — from a sprint board, a bid or a back-of-envelope — and converts it into the only two facts a calendar cares about: days and the date they end on.
Does doubling the crew halve the timeline?
In the division, almost — 25 days reads 13 once the whole-day grid has its say. In reality, rarely: that is Brooks's point, and the nine-women line is his too. Treat the linear answer as the floor and the caveat as the fee reality charges.
What if the effort estimate is wrong?
Then the finish date is exactly wrong by the same proportion — the arithmetic is honest about its input. Re-run with the revised effort; the walk costs nothing, which is the case for keeping the model simple enough to re-run.
Can the start land midweek?
Yes — the walk counts the start date as working day one wherever it falls in the week, and skips weekends from there. A Wednesday start finishes a five-day job on Tuesday; the calendar card shows the span and the weekend days inside it.