How to prepare a bill of quantities (BOQ) — practical step-by-step guide
The bill of quantities (BOQ) is the foundation of every construction offer, contract, and progress act. A poor BOQ means: lost tender, blown budget, disputes with the investor. Here is a practical 7-step guide for preparing a BOQ — for beginners and for anyone who wants to systematize the process.
What is a BOQ and why it matters
The bill of quantities (BOQ) is a structured document containing all work on a site, each line with quantity, unit, unit price, and total value. It is the "common language" of construction — client, contractor, designer, and accountant all read the same document.
A BOQ serves for:
- Tendering — basis for fixed pricing toward the investor
- Contract — appendix to the main contract, defines scope
- Progress acts — acts for completed work are written against the BOQ
- Budget control — plan vs actual per item
Errors in a BOQ multiply — wrong quantity in the offer = wrong invoicing = blown budget.
Step 1: Read the project documentation
Before you start counting — read. Mistake number one for beginners is to skip this step.
What to review:
- Architectural drawings (plans, sections, elevations)
- Structural drawings (slabs, beams, columns)
- Technical specifications (concrete classes, rebar, materials)
- General conditions (deadlines, warranties, special requirements)
What to ask the designer or investor:
- Concrete class (B25, B30 have different unit prices)
- Rebar type (B500B standard, BSt500S another)
- Site access (is there a road for trucks)
- Working hours (limited or not)
- Who supplies materials (you or the investor)
Do not bid on assumptions. One missing detail can deform the entire offer.
Step 2: Group items by category
The structure of a BOQ follows the logic of construction. Standard hierarchy:
1. Preparatory works (mobilization, clearing)
2. Earthworks (excavation, fill)
3. Structure
3.1. Formwork
3.2. Reinforcement
3.3. Concreting
4. Masonry
5. Roof
6. Finishing
6.1. Plasters
6.2. Screeds
6.3. Tiling
7. Plumbing
8. Electrical
9. HVAC
10. Facade
11. Specialized works
12. Demobilization / cleanup
The exact structure depends on the site. For a residential apartment it is one, for an industrial site — another.
Why hierarchy? Subgroup totals are useful for a quick overview. The investor sees the facade total separately from structure and decides more easily whether it fits the budget, without reading 200 line items.
In Construction Hub the nomenclature is built exactly on this logic — groups and subgroups with unlimited nesting, shared across all your BOQs, offers, and contracts.
Step 3: Calculate quantities
This is the most labor-intensive part. For each item determine:
- Quantity — exact value, not approximate
- Unit of measure — sq m, cu m, tons, m, pieces, linear meter
- Description — precise to avoid disputes
How to count different items:
| Type of work | Metric | Source |
|---|---|---|
| Masonry | sq m | Plan × height − openings |
| Concrete | cu m | Geometry from drawing |
| Reinforcement | tons | Rebar details × lengths |
| Formwork | sq m | Contact surface with concrete |
| Tiling | sq m | Floor area |
| Plasters | sq m | Wall plan × height |
| Electrical points | pcs | Electrical plan |
Important: add a waste allowance for every material — cut-offs, damaged elements, delivery errors. The standard percentage depends on the type of work.
When an IFC/BIM model is available — software reads the geometry automatically and saves a large part of this step.
Step 4: Add unit prices
For each item compute the final unit price:
Components:
- Material — with waste + delivery to site
- Labor — wages + social contributions
- Equipment — machine rentals, fuel
- Overhead — applied to direct costs (supervision, office, phones)
- Profit — per commercial judgment for the project
Where to source prices:
✅ Current quotes from 2-3 suppliers (not from a phone call) ✅ Your own database with prices from similar past projects ✅ Software-based price list linked to current market rates
❌ Prices "from memory" — the market changes ❌ Prices from long ago — materials get more expensive with inflation
In Construction Hub each item is linked to the nomenclature and pulls its unit price from a connected price list. A change in the price list automatically reflects in all open BOQs and offers.
Step 5: Contingency reserve and "invisible" items
Totals are auto-calculated by the software. Your task in this step is to decide two things that cannot be automated:
1. Contingency reserve:
- Additional amount on top of the total for work that cannot be 100% predicted at bidding (hidden defects of the substrate, design changes, execution specifics).
- The size depends on the project type — for renovations it is larger than for new build.
- In the offer it can be shown separately or included in the total price with an explanation.
2. "Invisible" items — often forgotten, always needed:
- Mobilization / demobilization
- Scaffolding (for facade work and heights above 4 m)
- Temporary structures (container, toilet)
- Waste removal
- Lab testing (concrete, ground)
- Geodesic surveying
- Designer supervision / investor's site control (if your responsibility)
Skipping them is a standard cause of budget overruns.
Step 6: Review and correct
Before finalizing — review yourself and ask a colleague for a second pass.
What to check:
- Top 5 highest line items — double-check quantities (the biggest errors live here)
- Top 5 highest unit prices — should be realistic against the market
- Comparison with similar projects — total price per built area should be in the range of your previous projects of the same type
- Sanity checks — sums are correct, VAT calculated correctly
If you have nothing to compare against (new project type) — get a second independent estimate from an experienced estimator or designer.
Step 7: Finalize and export
Final BOQ:
- Export as PDF with the company logo (for the investor)
- Excel copy (for internal work and edits)
- Archive in the system for future reference
- Send to the investor with a cover letter
In the PDF include: company info, date, site name, offer validity, payment terms.
In Construction Hub, after finalizing the BOQ, with one click you turn it into an offer for the client or a contract with a subcontractor — without re-entry. Versions are kept automatically, so when changes are requested you do not start from zero.
Common mistakes for beginners
| Mistake | Consequence |
|---|---|
| Missed "invisible" items (mobilization, scaffolding) | Budget overrun |
| Old prices from a long time ago | Margin loss with inflation |
| No waste allowance for materials | Real cost outside the budget |
| Wrong unit (sq m instead of cu m) | Catastrophe in the line |
| No second-person review | One mistake can deform 1-2 lines |
| Copying from an old offer without review | Wrong context, wrong prices |
BOQ in minutes with specialized software
Manual preparation of a BOQ for a substantial site takes a full working day or more. With specialized BOQ software:
- IFC/BIM import extracts quantities automatically from geometry
- AI matching links items to your nomenclature
- Prices come from a linked price list in real time
- Excel and PDF export — one click
- Versions and history — when changes happen you don't start from zero
- Convert from BOQ to offer or contract with a single click
Result: a BOQ for a substantial site — from hours down to minutes, depending on the input documents available.
Register free and create your first BOQ in minutes.