Don’t worry about measuring the width of the space since cinder blocks are commonly a uniform size. Cinder blocks come in various sizes and shapes, but the most common size is 8 by 8 by 16 inches (20 × 20 × 41 cm).
If you’d like to be as accurate as possible, hold the straight edge of a ruler across the block at the 8 in (20 cm) mark. Drag your chalk along the ruler’s edge to make a line that crosses the block.
If you don’t have a masonry blade (or a circular saw), purchase one at a local hardware store. If you only plan to use the circular saw for this single task, you may be able to rent one instead of buying it.
It’s also smart to protect your eyes from the small chunks of cinder block that the saw kicks up by wearing a pair of protective glasses. [7] X Expert Source Gerber Ortiz-VegaMasonry Specialist & Founder, GO Masonry LLC Expert Interview. 10 March 2020.
It’s important that you continue to check and make sure the saw is cutting straight through the cinder block as you’re cutting it.
Unplug the saw once you’re finished cutting through the block. If you’re using 1 hand to stabilize the block while your cut, keep your fingers out of the way of the saw! A circular saw could easily cut a finger off.
If the saw is covered in dust, also clean it off before putting the saw away.
You can purchase plastic safety goggles at any hardware store or at most home-improvement stores.
This method works most effectively on cinder blocks that have an open space running down the middle of the center beam. If you’re cutting cinder blocks without this open space, you’ll have a harder time splitting them.
Be careful not to whack the fingers holding the chisel in place when you’re hammering! The point of a flat chisel comes to an edge, not a point, making them ideal for splitting cinder blocks but not totally demolishing them.
Repeat this process as many times as needed if you’re splitting multiple cinder blocks.
