Job Completion Calculator

Base durations represent typical jobs in standard conditions. Actual times vary with property age, access difficulty, specification level, and unforeseen issues. Always add contingency - experienced tradespeople typically add 15-25% to their estimates.

Adding workers does not halve the time, because of coordination overhead, sequencing constraints, and shared workspace limitations. As an illustrative rule of thumb, this calculator assumes a second worker saves roughly 40% of the single-worker time and a third saves less again. This is a modelling guide rather than a guaranteed productivity figure — no British Standard governs crew speed, so treat it as indicative and adjust for your own trade and site.

Yes, for regulated work. Building control inspections can add 1-3 days per visit (typically 4-6 visits for an extension). Electrical Part P notifications need inspection before energising. Gas Safe registrations need completing before handover.

For external work (roofing, brickwork, rendering), expect 1-2 lost days per week in winter months. Concrete and mortar cannot be laid in freezing conditions. External decorating needs dry weather. Budget more contingency for autumn/winter starts.

Select "Custom Duration" and enter your own base estimate in working days. The calculator will still apply scope, worker, and delay adjustments to give you a more realistic completion estimate.