Estimate how many cinder blocks and bags of mortar your wall needs. Each dimension has its own unit selector (in/ft/yd/m).
Cinder block, like concrete block, is estimated by wall area. Measure each wall (any unit), subtract openings, and multiply the net area by 1.125 for a standard 8x8x16 block. Add about 5% for breakage and plan about three 80-lb mortar bags per 100 blocks.
Use this calculator for block walls where you need an approximate count of blocks, mortar and cost. It works from net wall area and a block coverage rate, so it can adapt to common 4 in and 8 in high block faces.
Start with the calculator that matches how your material is sold: area, length, volume, count, weight or electrical load. Enter one work area at a time, use the unit selector beside each measurement, then review the order quantity and cost fields before comparing supplier quotes.
Most calculators can save the current estimate in your browser, reload named estimates, print a copy, switch to dark mode or create a shareable link. Those tools are intended for planning and communication; always confirm final quantities, coverage rates, density, code requirements and pricing with the supplier or contractor responsible for the work.