Formula Used
Each line item uses a basis-driven quantity, then applies contingency, rounding, and optional limits.
- Raw Quantity = Rooms×Rate, Occupants×Rate, Area÷K×Rate, or Fixed.
- With Contingency = Raw Quantity × (1 + Contingency% ÷ 100).
- Final Quantity = Rounding(With Contingency), then Min/Max clamp.
- Grand Total = Rounding(Subtotal of included items).
- Area Conversion (if ft²) = ft² × 0.092903 = m².
How to Use This Calculator
- Enter rooms, total area, and expected occupants.
- Set a contingency percentage for spares and changes.
- Review line items and choose the correct basis.
- Adjust the rate to match your project standard.
- Click calculate, then export CSV or PDF as needed.
Example Data Table
Sample inputs and typical outputs for a small fit-out.
| Scenario | Rooms | Area (m²) | Occupants | Contingency | Estimated Total |
|---|---|---|---|---|---|
| Site Office | 6 | 240 | 28 | 7% | ~78 items |
| Store & Admin | 4 | 160 | 18 | 5% | ~52 items |
| Large Camp Office | 10 | 420 | 55 | 8% | ~160 items |
Your totals depend on chosen items, basis, and rounding.
Workstation Seating Benchmarks
Most construction site offices plan one task chair per seated occupant and one spare chair per 12–15 seats. Using a 7% contingency typically covers breakage and short-term additions without overbuying. If you expect shift overlap, increase the per person rate to 1.10–1.25 to avoid daily shortages. Many projects also include one supervisor chair per team, planned as fixed baseline quantity.
Desk and Table Ratios by Function
Desks generally track headcount at 1.0 per person, but supervision teams may share hot desks at 0.70–0.85. Meeting tables are often planned at about one table per three rooms or zones, then rounded up. For training rooms, a fixed quantity can be added to represent dedicated furniture that does not scale.
Storage Allowance by Floor Area
Storage cabinets and shelving depend more on floor area than on people. A practical starting point is 0.6–1.0 cabinets per 10 m² for admin and records, and 0.3–0.6 per 10 m² for general stores. When area is entered in square feet, it is converted to square meters to keep rates consistent. If archives are required, increase storage rates by 15–25% and reserve wall length for filing.
Rounding and Minimum Control
Rounding up is recommended for critical items such as chairs, desks, and reception counters. For non-critical items, standard rounding reduces excess while still meeting demand. Minimum limits are useful when a project requires at least one reception counter or a minimum number of cabinets, even on small sites with few rooms. Maximum limits help prevent oversizing when area inputs include circulation or covered outdoor zones.
Procurement Readiness and Packaging
Quantities should be aligned with vendor pack sizes. For example, chairs may ship in cartons of two and cabinets may ship by pallet, so final totals may be adjusted to the next pack. Exporting to CSV supports BOQ templates, while the PDF summary supports approvals and site handover documentation. Use the notes column to capture model codes, finishes, fire ratings, and lead times for smoother purchasing.
FAQs
1) What does the contingency percentage do?
It increases every included item by the same factor, then applies rounding. Use 5–10% for typical site conditions, and higher if furniture damage risk or scope uncertainty is high.
2) Which basis should I use for chairs and desks?
Per person is the common standard for workstations. If you have hot-desking, reduce the rate below 1.0. If you have shift overlap, increase the rate above 1.0.
3) How should I estimate meeting tables?
Use per room when meeting spaces scale with the number of rooms or zones. A rate around 0.33 means one table per three rooms, then rounding up ensures availability.
4) Why are storage items based on area?
Storage demand correlates with floor area and document volume. Using per 10 m² or per 100 m² keeps cabinet counts stable as occupancy fluctuates, especially in shared offices.
5) Can I set minimum and maximum quantities?
Yes. Minimum values enforce required provisions, while maximum values cap counts for space limits or budget control. Limits are applied after rounding for predictable results.
6) What do the CSV and PDF exports include?
They include project inputs, each item’s basis, raw quantity, contingency quantity, final quantity, and totals. Use CSV for estimating sheets and PDF for sign-off and procurement requests.