Concrete Block Steps Calculator

When most folks begin a concrete block step construction project they grab a tape measurer, get a general idea of how big the space is and proceed to order blocks based off gut instinct, not exact science. That typically lead to either a stack of extra materials collecting dust in the driveway, or having to stop halfway through building because something was wrong.

The calculator above do all the math work for you. It lets you do all the planning and leave the math to it. It takes your real world measurements and turns them into an accurate list of required materials. It considers size of each block, the thickness of mortar joints, the core fill and waste. Then it provides you with actual shopping list to go out and buy what you need.

How to Use the Concrete Block Step Calculator

Rise and run form the backbone of a solid stair. The run refers to the horizontality of each step (its width), and the rise are the verticality (how far up it goes). To make something that’s pleasant to climb, you must find the right proportions different than these two figures. Too much rise, as in, hiking up some mountain stairs, is going to be unpleasant. Too little rise… As in, wading around in some mud-filled room, is also not ideal.

The Rise & Run calculator will figure out exactly how many courses and risers you’ll need based on your total height and desired tread depth. That way, you don’t end up with a lop-sided stair where you have one weird fractional rise at the bottom. That kills the whole thing in how it looks and how it work.

The thing few novices grasp about block sizes is its importance. Standard CMUs (meaning 8×8×16) is the workhorse of home stair construction. But the calculator lets you select other options, from 12- to 6- inch to even 4-inch wide blocks. Why? Wider blocks is heavier and stiffer, but narrower blocks may be better for making decorative trimwork or fitting into tighter spots.

The mortar joint thickness is also key, and you enter it as an option. Generally, it’s a three-eighths-inch joint. You’d set this to zero if designing something like a dry-stack wall. That slight change affects overall course heights. And that will affect just how many block will span from the ground up to the landing.

The second choice inside the block, one that determines both durability and cost, is what you do with those cores: pour in concrete? Fill them with gravel? Leave ’em empty? Concrete locks all those steps into one solid mass. It’s heavy and strong. Gravel’s light and inexpensive, it provides little structural strength. Depending on the size of your step and which fill you choose, the calculator will estimate the required amount of fill material. From there, it translates that into bags of mix for you to buy. No more guessing at how many bags of 80 pounders you’ll need.

This is where budgets often blow up, because core fill is rarely as cheap as the blocks themselves. Core fill will never be as inexpensive than buying the blocks.

Don’t forget the bottom. Dirt doesn’t hold concrete blocks very well at all. You must have some sort of solid foundation, like compacted gravel, under them so that their weight is distributed evenly and they don’t settles over time. The tool figures out amount of gravel needed by figuring in the area of the steps (plus an overhang for extra support). Typical is 4-6″ of compacted stone. You can change this on the calculator. If the foundation isn’t good, the blocks will crack. This happens even if you lay down perfect mortar. Your steps will also be uneven.

Construction is an ugly business. There will be broken blocks on the way in, cuts needed at every corner and return. To accommodate all this waste, we add a percentage to our materials list called the Waste Factor Input. For simple steps, ten percent is a good starting point. For complex designs with lots of cuts, it might even go as high as 15-20 percent. It’s always best to round up rather than run out in the middle of a project.

The output gives a nice breakdown of how many caps, blocks, fill, and mortar will be required for the job. Rough CMU surface is covered by the cap blocks. These give you a smooth tread and finished look. How much of the tread do you want capped? The full tread? Only the nosing? Nothing? The number of blocks used changes based off what option you select. It is a small detail, but it matters.

The more you plan the better the list. Less money wasted. Fewer trips to the supplier. Plan using the estimator. Check local requirements for footings and drainage. Build confidently. Not the third time but the first. You should of planned better.