Complete Guide for Engineers, Contractors, and Quantity Surveyors (Philippines)
The quantity estimating procedure is a fundamental process in construction project planning and cost control. It involves identifying, measuring, and calculating the exact quantities of materials, labor, and resources required to complete a project based on approved drawings and specifications.
In the Philippine construction industry, accurate quantity estimating is essential to avoid budget overruns, material shortages, disputes, and project delays. This pillar guide explains the standard quantity estimating procedure used by engineers, contractors, and quantity surveyors, especially for residential and small-to-medium projects.
What Is Quantity Estimating in Construction?
Quantity estimating is the process of converting construction drawings into measurable quantities that are later priced to form the project cost estimate or Bill of Quantities (BOQ).
It is commonly used for:
- Project budgeting
- Contractor bidding
- Material procurement
- Cost control and monitoring
Standard Quantity Estimating Procedure (Step-by-Step)
1. Review Construction Drawings and Specifications
The first step is a detailed review of:
- Architectural plans
- Structural drawings
- Plumbing and sanitary layouts
- Electrical plans
- Technical specifications
Using outdated drawings is one of the most common causes of quantity errors.
2. Define and Break Down the Scope of Works
Divide the project into manageable work sections:
- Site works
- Concrete works
- Reinforcement works
- Masonry works
- Carpentry and roofing
- Finishing works
- Electrical works
- Plumbing and sanitary works
A clear scope breakdown ensures no work item is missed.
3. Perform Quantity Take-Off
Quantity take-off is the process of measuring quantities directly from drawings using standard units:
| Work Item | Unit |
|---|---|
| Concrete | Cubic meter (cu.m) |
| Reinforcement bars | Kilogram (kg) |
| CHB | Pieces (pcs) |
| Plastering / Painting | Square meter (sqm) |
| Roofing | Square meter (sqm) |
Accuracy at this stage determines the reliability of the final estimate
4. Apply Material Factors and Allowances
Allowances are added to account for:
- Wastage
- Cutting loss
- Overlaps and lap splices
- Construction tolerances
Typical examples:
- Concrete: +5% to 10%
- Reinforcement steel: +3% to 5%
- CHB: +5%
5. Calculate Labor Requirements
Labor quantities are computed based on:
- Productivity rates
- Project complexity
- Location and accessibility
Labor may be calculated as:
- Man-days
- Per unit basis (per sqm or per cu.m)
- Lump sum
6. Determine Material and Labor Cost
Pricing is based on:
- Current market prices
- Supplier quotations
- Standard labor rates
- Historical project data
Because material prices fluctuate, especially cement and steel, estimates must be updated regularly.
- Updated Construction Material Price List Philippines
- Why Construction Material Prices Fluctuate
7. Prepare the Bill of Quantities (BOQ)
All measured quantities and costs are summarized into a Bill of Quantities, containing:
- Description of work
- Unit of measurement
- Quantity
- Unit cost
- Total amount
The BOQ is used for:
- Contractor bidding
- Client approval
- Project cost control
8. Review, Validate, and Cross-Check
Before finalizing the estimate:
- Recheck all take-off measurements
- Compare with similar completed projects
- Verify compliance with drawings and specs
This step helps eliminate costly estimating errors.
Importance of Proper Quantity Estimating
✔ Accurate project budgeting
✔ Competitive and realistic bidding
✔ Reduced material waste
✔ Better procurement planning
✔ Improved project cost control
Common Quantity Estimating Mistakes to Avoid
- Using outdated drawings
- Skipping small items (anchors, ties, accessories)
- No wastage allowance
- Incorrect unit conversions
- Overlooking labor productivity
Tools Used in Quantity Estimating
Modern estimators use:
- Excel-based quantity take-off sheets
- Digital construction calculators
- Historical cost databases
Conclusion
A proper quantity estimating procedure is the foundation of successful construction projects. By following a systematic approach—from plan review to BOQ preparation—engineers and contractors can ensure accurate costs, efficient resource use, and smooth project execution.
For faster and more reliable estimates, use the construction calculators and estimating tools available on ProjectCostingPH.