Formula Reference
The production rate is the whole answer, and it should be yours
Each phase opens with a labor rate in man-hours per 100 square feet — framing at 8, drywall and electrical at 6, flooring and plumbing at 5, ceilings and HVAC at 4, painting at 3. Those are this page's own starting assumptions and nothing more. They have no published basis, they are not survey results, and they are not anybody's industry average. They exist so the tool has something in the box when it opens, and the first thing worth doing with them is replacing them.
We do not ship a rate library and do not intend to, for the reason the productivity translator gives at more length: the rate books that carry real unit productivity are commercial products and the trade-association labour manuals are members-only, so we cannot read them to you or quote them. More usefully, a rate from a book describes a stranger's crew on a stranger's job. Yours is better and you already own it. Take a finished job of the same type, divide the square feet installed by the labor-hours charged against it, multiply by 100, and that is your MH/100 SF. Do it for three or four jobs: a tight spread means you can schedule on the average, a wide one means something you have not isolated — access, ceiling height, how cut up the work was — is driving the hours.
Man-hours, crew-days and duration are three different numbers
Ten thousand square feet of framing at 8 MH/100 SF is 800 man-hours. Four workers on eight-hour days put in 32 man-hours a day, so that is 25 crew-days, and the bar on the chart is 25 working days long. Put eight workers on it and the same 800 man-hours become 12.5 crew-days — the cost has not moved at all, only the calendar has, and only if the work can genuinely absorb eight people at once. That last condition is the one this page cannot check for you.
So read the three numbers for what they are. Man-hours are what the phase costs. Crew-days are what it occupies. Duration is crew-days rounded up, because you cannot buy a third of a day of a four-man crew. The project summary adds man-hours across phases honestly, but it cannot add durations that way, which is what the sequencing options are for.
What the bar chart is, and what it is not
This is a bar chart, not a network schedule, and the distinction is the difference between a picture and a calculation. Carnegie Mellon's Project Management for Construction puts the limitation plainly: bar charts are widely used to communicate the current state of a project, but "for planning purposes, bar charts are not as useful since they do not indicate the precedence relationships among activities", so "a planner must remember or record separately that a change in one activity's schedule may require changes to successor activities."
That is exactly this page. It offers three sequencing rules — follow the last phase, run alongside it, or start on a fixed day — and no dependency network behind them. It therefore computes no critical path, which the same chapter defines as "the longest possible path through the 'network' of project activities", whose duration "represents the minimum time required to complete a project". No network, no critical path, and no float either: nothing here will tell you which phase can slip harmlessly and which one drags the handover with it. The trade-order warnings it does raise, such as painting overlapping drywall, are a sanity check on the order you typed in, not a constraint the schedule is solving.
The peak crew figure is worth reading, though. It counts the workers on site on each individual day and reports the largest, so two phases you set to run in parallel show up as the sum of their crews. That is the number to check against how many people you can actually field, how many can fit in the space, and what your general contractor's site logistics will bear.
What this schedule must not be used for
It is a planning sketch, not a contract schedule and not a delay claim. It carries no mobilisation, no submittal or procurement lead time, no inspections, no punch list, no holidays, no weather allowance and no float. It assumes each crew works at the rate you entered from the first day to the last, arrives complete, and never waits on another trade. It has no dependency logic, so it cannot tell you what a slip costs downstream. If the rate you entered is optimistic, every date on the chart is optimistic by exactly the same proportion. Use it to size the work and to argue about crew loading; put the result against a real schedule, and against your own completed jobs, before anyone else sees a date.
Frequently asked questions
Turn the quantity into labor-hours using a production rate, divide those by the hours the crew actually puts in each day, and round up to whole days. Ten thousand square feet at 8 labor-hours per 100 square feet is 800 labor-hours; four workers on eight-hour days is 32 hours a day, so 25 crew-days. That is a duration for the work itself and nothing else: it assumes the area is available, the crew turns up complete, and nobody is waiting on another trade, an inspection or the weather. Take the production rate from your own finished jobs, because it is the only part of the sum that is not exact.
Multiply each quantity from the takeoff by the labor-hours that activity takes per unit, and add the results up activity by activity rather than blending everything into one average, because an average hides whichever item is really driving the hours. Man-hours and labor-hours are the same measure: one worker for one hour. They tell you cost, not elapsed time — two workers on a task that cannot be split do not halve the duration. The arithmetic is exact and the production rates are not, so check the total against a completed job of similar scope before you commit to it.
A Gantt chart is a drawing: one bar per activity, positioned by start date and sized by duration. A critical path is a calculation on a network of activities linked by precedence relationships, and it is the longest path through that network, which is why its length is the shortest time the project can take. A bar chart shows you what is planned but not what depends on what, so slipping one bar does not move the bars that should follow it. The timeline on this page is a bar chart. It has no dependency network behind it and therefore computes no critical path and no float.
The definitions of the critical path and the limits of a bar chart are quoted from chapter 10 of Project Management for Construction: Fundamental Scheduling Procedures, published free online by Carnegie Mellon University's Department of Civil and Environmental Engineering. No production rate on this page is sourced, because no production rate on this page is claimed to be: the figures each phase opens with are editable defaults, stated as assumptions, and the published unit-productivity data for the trades sits behind commercial rate books and members-only association manuals we cannot read or reproduce.