Construction
Construction Labor & Duration Calculator
Estimate working days, calendar days, and total labour cost for any construction job
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Total units of work (m², m³, pieces — unit-agnostic).
Units per worker per day. Tile ≈ 10 m², paint ≈ 25 m², block work ≈ 6 m².
Standard Saudi weekly rest day.
~15 paid Saudi public holidays per year.
Working days
Calendar days
Adjusted for Fridays and public holidays.
Output per day
Estimated completion
Total labour cost
How does it work?
The labour and duration calculator answers the foreman's first scheduling question: with this many workers at this productivity rate, when does the job finish? Multiplying the productivity rate (units per worker per day) by the workforce size gives the daily output. Dividing the total work volume by daily output and rounding up gives the working days. Calendar days are then adjusted: Saudi sites typically rest Friday, so working days × 7/6 captures the lost day per week; an additional ~4% accounts for the ~15 paid public holidays per year (Eid Al-Fitr, Eid Al-Adha, National Day, Founding Day). Total cost is straightforward: working days × workers × daily wage.
Core formula
Productivity per day determines working days; calendar days adjust for rest days and holidays; cost scales with workers and wage.
Working Days = ⌈Volume ÷ (Rate × Workers)⌉ | Calendar Days = Working × 7/6 (Fri) × (1 + 15/365) (Holidays) | Cost = Working × Workers × Wage
Worked example — 500 m² of tile laying
Inputs: work volume = 500 m², productivity rate = 10 m²/worker/day, workers = 5, daily wage = 150 SAR, exclude Fridays = yes, exclude holidays = yes.
- Productivity per day = 10 × 5 = 50 m²/day
- Working days = ⌈500 / 50⌉ = 10 days
- Calendar (Fri adj.) = 10 × 7/6 = 11.67 days
- Calendar (holidays adj.) = 11.67 × (1 + 15/365) = 12.15 → ⌈⌉ = 13 days
- Total labour cost = 10 × 5 × 150 = 7,500 SAR
- If start = today, completion ≈ today + 12 days
Common mistakes to avoid
- Quoting calendar days as if they were working days — confuses the client and shortens the perceived schedule.
- Using an over-optimistic productivity rate — site reality is usually 70–80% of textbook figures.
- Forgetting that some holidays overlap with Fridays — the multipliers are independent and slightly overcount when they do.
- Not adjusting for inexperienced labour — first-time workers run at 50–60% of standard rates for the first week.
Tips for accurate estimates
- Saudi standard rates per worker per 8-hour day: tile laying 8–12 m², painting 25–30 m², block work 6–8 m².
- Add a 10–15% schedule buffer for site disruptions (rain, deliveries, inspections).
- When pricing for the client, quote calendar days plus a 10% buffer — round up to the nearest week.
- Track actual productivity on the first few days and re-baseline the estimate.
Frequently Asked Questions
Why are calendar days bigger than working days?
Working days are pure 'productive on-site' days. Calendar days include weekly rest (Friday in Saudi practice) and paid public holidays — they represent the time on the wall calendar, which is what the client sees.
Are the calendar-day multipliers exact?
They're approximations. The Friday multiplier (7/6) is exact for a 6-on-1-off rotation; the holiday multiplier (1 + 15/365) assumes ~15 paid public holidays evenly spread. When the two overlap the calculator slightly overcounts — safer than under-counting.
Where do the standard productivity rates come from?
They're industry averages from construction estimating handbooks. Tile laying ≈ 10 m²/worker/day, painting ≈ 25 m²/worker/day, block work ≈ 6 m²/worker/day are typical Saudi figures.
Does this account for Ramadan working hours?
No — during Ramadan most Saudi construction sites operate 6 hours instead of 8. Multiply your productivity rate by 0.75 to compensate.
Can I model multiple trades?
Run the calculator once per trade and add the durations. For overlapping trades on the same critical path use the longer estimate plus a small buffer.
What if I add more workers?
The relationship is linear: doubling the workforce halves the working days. In practice large crews suffer coordination overhead. Stay realistic above 10 workers per trade.
Is the daily wage gross or net?
The calculator uses whatever number you enter — typically the gross daily wage including GOSI and accommodation allowances. For accurate cost-to-company use the fully-loaded figure.
Why does the completion date sometimes look off?
The date arithmetic is pure Gregorian: start date + (calendar days − 1). It doesn't skip weekends — those are already baked into the calendar-days adjustment.
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