How to Prepare a Bill of Quantities: Complete Step-by-Step Guide

What Is a Bill of Quantities?

A bill of quantities (BoQ) is a document used in construction that itemizes all the materials, parts, and labor required for a project, along with their quantities. It forms the basis for tendering, cost estimation, and project management.

The BoQ allows contractors to price work consistently, ensures fair comparison between bids, and provides a reference for valuing work during construction.

The Traditional BoQ Preparation Process

Step 1: Obtain and Review the Drawings

Before you begin, gather all relevant drawings:

• Architectural floor plans (all levels)
• Elevations and sections
• Door and window schedules
• Structural drawings (if available)
• MEP drawings (if available)

Verify the scale of each drawing. This is critical—incorrect scale means incorrect quantities.

Step 2: Understand the Measurement Standard

Different regions use different measurement standards:

Standard	Region	Description
NRM2	UK, international	New Rules of Measurement for capital building work
SMM7	UK, international	Standard Method of Measurement (older, still used)
POMI	International	Principles of Measurement International
CSI MasterFormat	USA	Construction Specifications Institute format
AACPI	Australia	Australian Asphalt Pavement Code

Choose the standard appropriate for your project and region.

Step 3: Measure Quantities from Drawings

This is the core of BoQ preparation. For each building element, you need to:

For linear items (measured in metres/m):

• Measure the length of skirting boards, cornices, handrails, pipes, cable runs
• Include allowances for corners, joints, and waste where applicable

For area items (measured in square metres/m²):

• Calculate floor areas (length × width per room)
• Calculate wall areas (wall length × height, minus openings)
• Calculate ceiling areas
• Calculate plastering, painting, and tiling areas

For count items (measured in numbers/nos):

• Count doors, windows, sanitary fixtures, light fittings, switches
• Count electrical points, sockets, outlets

For volume items (measured in cubic metres/m³):

• Calculate concrete volumes (length × width × depth)
• Calculate excavation volumes
• Calculate fill and backfill volumes

Step 4: Organize by Trade Categories

Structure your BoQ by construction trade. A standard trade breakdown includes:

1. Preliminaries — site setup, temporary works, security
2. Substructure — excavation, foundations, concrete
3. Superstructure — walls, columns, beams, floors
4. Roofing — roof structure, covering, insulation, gutters
5. External walls — brickwork, blockwork, cladding, insulation
6. Internal walls — partitions, plastering, drywall
7. Floors — screed, tiling, timber, finishes
8. Ceilings — plaster, suspended ceilings, paint
9. Doors and windows — frames, doors, windows, ironmongery
10. Finishes — painting, decorating, special finishes
11. Fittings — kitchen, bathroom, sanitary fixtures
12. Electrical — wiring, fittings, distribution
13. Mechanical — plumbing, HVAC, fire protection
14. External works — paving, landscaping, drainage

Step 5: Write Item Descriptions

Each BoQ item needs a clear, unambiguous description. A good description includes:

• The work being done (e.g., "Ceramic floor tiling")
• The material specification (e.g., "600×600mm polished porcelain")
• The location (e.g., "to ground floor living area")
• The measurement unit (e.g., "m²")

Example: "Ceramic floor tiling, 600×600mm polished porcelain tiles, cement mortar bed, to ground floor living areas — m²"

Step 6: Apply Units and Quantities

Assign the correct unit of measurement and the calculated quantity to each item:

Item	Unit	Quantity
Ceramic floor tiling 600×600mm	m²	45.20
Skirting boards, ceramic	m	28.40
Wall plastering 15mm thick	m²	120.60
Internal doors, hardwood	nos	6
Wall painting, 2 coats emulsion	m²	180.30

Step 7: Review and Check

Before finalizing your BoQ:

• Cross-check quantities against drawings
• Verify units are consistent
• Check for missed items (common omissions: sealants, trims, thresholds)
• Ensure descriptions are clear and complete
• Confirm trade categorization follows the chosen standard

Step 8: Format and Present

Present your BoQ professionally:

• Use a clear table format with columns for item number, description, unit, quantity, rate, and total
• Include a cover page with project details
• Add a preliminaries section
• Include a summary page with trade totals

The Modern Way: AI-Powered BoQ Preparation

The traditional process above takes 4–8 hours for a standard residential project. With Enormous Buildings, the entire process is automated:

1. Upload your floor plan
2. Wait 60 seconds while AI measures every element
3. Review the generated BoQ (edit if needed)
4. Export to Excel, CSV, or PDF

The AI handles Steps 1–7 automatically—measuring, categorizing, describing, and quantifying—leaving you to review and finalize.

What AI Handles Automatically

• Scale detection from the drawing
• Element identification (walls, floors, doors, windows, etc.)
• Quantity calculation with precise measurements
• Trade categorization following standard formats
• Item description generation
• Unit assignment

What You Still Control

• Reviewing and editing quantities
• Adding custom items or notes
• Applying rates and pricing
• Final formatting and presentation

Common Mistakes in BoQ Preparation

1. Incorrect Scale

Using the wrong scale is the #1 source of errors. Always verify the scale bar on the drawing. AI tools like Enormous Buildings detect scale automatically, eliminating this risk.

2. Missing Items

It's easy to forget small items like sealants, trims, thresholds, or junction boxes. A systematic trade-by-trade approach (or AI automation) prevents omissions.

3. Inconsistent Units

Mixing units (e.g., measuring some walls in mm and others in m) causes calculation errors. Stick to one system throughout.

4. Double Counting

Measuring the same area twice (e.g., counting a doorway in both wall area and door count) inflates quantities. Clear item descriptions prevent this.

5. Ignoring Waste Allowances

Materials need waste allowances (typically 5–10% for tiling, 2–5% for paint). Include these in your quantities or rates.

BoQ Preparation Checklist

• All drawings obtained and scale verified
• Measurement standard selected (NRM2, SMM7, etc.)
• All trades covered (substructure to external works)
• Quantities measured and cross-checked
• Item descriptions clear and complete
• Units consistent throughout
• No double counting
• Waste allowances included
• BoQ formatted professionally
• Reviewed by a second person (or AI-verified)

Save Hours with AI BoQ Generation

Preparing a bill of quantities manually is time-consuming and error-prone. Enormous Buildings automates the entire process—upload a floor plan and get a complete, trade-categorized BoQ in under 60 seconds.

Generate your BoQ now →