CHB Calculator Philippines
Calculate the number of concrete hollow blocks required for your wall.
This calculator provides an approximate quantity for preliminary planning and material estimation. Actual CHB requirements may vary depending on block dimensions, mortar joints, wall layout, construction method and site wastage.
Mortar Material Estimate
Estimate cement and sand required for laying the calculated CHB wall.
Based on 0.000 m² net wall area.
Calculation assumptions
- CHB size: 4" (100 mm)
- Mortar mix: 1 : 3 cement : sand
- Preliminary CHB-laying mortar estimating factor
- Cement bag size: 40 kg
Actual consumption may vary with joint thickness, block dimensions, workmanship, material properties and site wastage.
How to Use the CHB Calculator Philippines
This CHB Calculator Philippines helps homeowners, contractors and estimators calculate the approximate number of concrete hollow blocks required for a wall. It can also provide a preliminary estimate of cement and sand required for laying the CHB.
- Enter the total wall length.
- Enter the wall height.
- Enter the combined area of doors, windows and other openings that should be deducted from the wall.
- Select the required CHB thickness.
- Select an allowance for cutting, breakage and normal site wastage.
- Click Calculate CHB to see the estimated quantity.
- If required, open Estimate Mortar Materials to estimate cement and sand for CHB laying.
How Many CHB Are Needed Per Square Meter?
A common preliminary estimating basis for standard concrete hollow block walls is approximately 12.5 CHB per square meter. This corresponds to a nominal block face of approximately 400 mm × 200 mm.
For example, a wall with a net area of 20 m² would require approximately:
20 m² × 12.5 CHB/m² = 250 CHB
An allowance may then be added for breakage, cutting and other normal site losses. The calculator allows you to select the allowance separately.
CHB Wall Area Formula
Before calculating the number of hollow blocks, determine the gross wall area:
Gross Wall Area = Wall Length × Wall Height
The total area of doors, windows and other openings is then deducted:
Net Wall Area = Gross Wall Area − Area of Openings
The estimated CHB quantity is then calculated from the net wall area.
4-Inch, 5-Inch and 6-Inch CHB
Concrete hollow blocks in the Philippines are commonly identified by their approximate wall thickness. Typical choices include 4-inch (about 100 mm), 5-inch (about 125 mm) and 6-inch (about 150 mm) CHB.
The appropriate block thickness depends on the wall location, structural requirements, approved plans and project specifications. CHB thickness should not be selected based only on material cost.
CHB Mortar Estimate
The mortar calculator provides a preliminary estimate of cement and sand required for laying the CHB only. The default mortar basis is a 1:3 cement-to-sand proportion by volume, consistent with the mortar proportion stated in the DPWH Standard Specification for Masonry Works.
The estimated mortar quantity varies with CHB thickness because wider blocks generally require more laying mortar. An allowance can also be added for normal site losses.
Important: The mortar estimate does not include plastering or rendering, CHB cell filling or grouting, reinforcement, concrete stiffeners, tie columns, bond beams or other masonry materials.
Example CHB Calculation
Suppose you have a wall measuring 5 m long × 3 m high with 1 m² of doors and windows.
Gross wall area: 5 × 3 = 15 m²
Net wall area: 15 − 1 = 14 m²
Estimated CHB: 14 × 12.5 = 175 pieces
Recommended quantity with 5% allowance: approximately 184 CHB
You can test the same example directly using the calculator above.
CHB Calculator Philippines Frequently Asked Questions
How many CHB do I need per square meter?
For preliminary estimating, approximately 12.5 standard CHB per square meter of net wall area can be used. Actual consumption can vary with block dimensions, joints, cutting and workmanship.
Should I deduct doors and windows?
Yes. Large openings such as doors and windows should normally be deducted from the gross wall area when estimating the number of CHB. The calculator provides a separate field for the combined opening area.
Should I add allowance to the CHB quantity?
Adding an allowance can help account for breakage, cutting and normal site losses. The appropriate percentage depends on project conditions, which is why the calculator allows the allowance to be changed.
Does the mortar estimate include plastering?
No. The mortar estimate covers CHB laying mortar only. Plastering, rendering, grouting, reinforcement and other masonry works should be estimated separately.
Can I use this calculator for structural design?
No. This tool is intended for preliminary quantity and material estimation. Structural walls and other critical construction work should follow the approved drawings, specifications and requirements of the project's licensed design professionals.
Important Estimating Note
Results from this calculator are approximate quantities for planning and budgeting. Actual requirements may vary because of block dimensions, mortar-joint thickness, workmanship, wall configuration, cutting, breakage and site conditions.
For construction, always refer to the approved architectural and structural drawings, project specifications and applicable Philippine construction requirements.