CHB Calculator

How the calculation works

Net area = wall length × height − openings. Blocks = ceiling[net area ÷ (nominal length × nominal height in metres) × (1 + allowance ÷ 100)].

A worked example

A 10 m × 3 m wall minus 2 m² of openings has 28 m² of net area. A 400 × 200 mm module gives 12.5 blocks/m²: 350 before allowance, or 368 whole blocks with 5%.

Assumptions & exclusions

For a single block layer with a uniform module. Round up only after applying the allowance. Does not estimate mortar, plaster, grout, reinforcement, lintels or labour. Block thickness does not affect the face count; select thickness and strength from your approved plans. Separate walls and unusual patterns may need additional cuts.

Should I enter actual or nominal block dimensions?

Enter the nominal module, including the planned joint. For example, a 390 × 190 mm block with 10 mm joints uses a 400 × 200 mm module. Confirm actual sizes locally; the default is an estimating assumption.

What does the price include?

Only the estimated material quantity multiplied by your entered price. No live prices are supplied. Delivery, labour, accessories and any taxes not included in your supplier’s price are excluded. Blank prices leave cost uncalculated; zero is treated as an explicit ₱0 price.