Line-of-Balance Duration Calculator
Rhythmic flow duration with overlap and break adjustments.
Inputs
Result
Formula
| Rhythmic flow | T = (m + n − 1) × t |
| With breaks | T = (m + n − 1) × t + Z − C |
| Sections | m, the number of flow sections |
| Processes | n, the sequential trades |
| Cycle time | t, days one crew spends per section |
| First section | n × t |
Four sections, three processes, a 3-day cycle and no breaks: (4 + 3 − 1) × 3 = 18.0 days — the first section finishes on day 9 and the last section starts on day 9.
FAQ
Why (m + n − 1) × t rather than m × n × t?
Because overlapping is the whole point. m × n × t assumes each trade finishes a section before the next starts anywhere — no flow at all. In reality the first crew moves on and the second follows in behind, so only the first trade has a ramp-up and the last a tail, saving on the order of (n − 1) × (t − 1). The more sections, the bigger the saving over sequential working.
Is more sections always better?
No. More sections improve flow and shorten the programme, but each holds less work, crews move more often, and the face may be too small to hold a crew — efficiency drops. As a rule each section should give a crew two to three days of continuous work; below two days, mobilisation dominates and the real duration exceeds the calculation.
Why is a technical break not part of the cycle time?
Because the crew is idle during a break and produces nothing, whereas the cycle measures actual work. Folding 7 days of curing into the cycle turns a 3-day cycle into 10 and stretches the whole line; the correct treatment is a separate addition to the total, with other trades scheduled through the gap. This is why curing time dominates the programme.
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Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.