How to use the blockwork calculator
This calculator helps you estimate block quantities and geometric mortar volume for a single-leaf wall. It is intended for quantity takeoffs, early budgets and checks against a measured schedule. Start with the dimensions or quantities for one clearly defined item of work. Enter values in the units shown beside each field; millimetres and metres are not interchangeable.
Assumes a single leaf, uniform joints and no openings. Mortar is a simple geometric joint volume; it excludes frogs, hollow cores, bedding patterns, dry-mix conversion and waste. Confirm actual unit sizes.
Worked example
A 6 m × 2.4 m wall has 14.4 m² of gross face area. Divide this by one unit’s face module, including the joint, then add the selected waste allowance.
Before you order
Compare the result with your drawings and supplier information. Keep the original net quantity separate from allowances, and round purchasing quantities only at the ordering stage. Check whether delivery, labour and related materials belong elsewhere in your estimate. If the drawing or specification changes, update the inputs and record the revised basis instead of reusing an earlier total.
For the concepts behind this calculation, read Wastage Factor, Takeoff (Quantity Takeoff), Unit Rate.