How do you calculate consumption of mortar in blockwork?

To calculate the consumption of mortar in blockwork, first determine the total area of the blocks being laid. Then, estimate the joint thickness (typically between 10-15 mm) and calculate the volume of mortar needed for the joints by multiplying the total area by the joint thickness. Finally, convert this volume to bags of mortar based on the volume covered by one bag, usually provided by the manufacturer. Adjust for wastage, typically around 10%.