Straw Bale House Calculator:
How many bales do you need?

Once you’ve got your design nailed down, the next step is to start looking at materials, and that’s where a straw bale house calculator comes in handy! As part of your materials ordering and estimating process, how many straw bales are needed to build the design is a number you’ll need to know. 

There are a few different methods to calculate bale requirements, and we’ve built a free tool for you to use around our preferred method. Click here to use the Straw Bale House Calculator below, or read on to learn more about the different options available for calculating straw bales for your project.

Basic Method for Calculating the Number of Bales

One way is to simply make assumptions about the general size of your house and use a calculation method based entirely on home square footage and roof design. This can work well with simple designs. For example, where a home is basically a square or rectangle; however, this method becomes fairly rough when a home has more angles, turns, and curves in the exterior walls, as all of those construction details use more bales. 

Keep in mind the more custom bales you need to tie, the more waste you will have to calculate into the estimate, even if you use the cut-offs of the bales elsewhere in the building. For an example of this simple calculation method, check out this table based on square foot calculations by IronStraw.org.

Straw Bale House Calculator Method Based on Square Footage

Another way to estimate your bale needs is to go a bit more in-depth and calculate the total number of bales based on the square footage of the total wall surface area. Here’s the process:

  1. Measure Square Footage of Wall Surface: First, calculate the total lineal feet of straw bale wall and then multiply that by the height of the walls. This yields the square footage of the wall surface. You can then remove the square footage of window and door openings in the wall surface from this number. 

  2. Account for a gable roof: measure one-half the width of the building at the gable and multiply it by the total height of the gable end. That will give you the square footage of the entire gable as if you took the two triangles and glued them back together in the shape of a square at each gable end. 

  3. Determine Square Footage Surface Area for Your Bales: Once you have all of the openings removed, divide the total square footage by the square footage of your bales. For this, consider a 14″ tall by 36″ long bale would have 504 square inches or 3.5 square feet of bale surface area facing the interior/exterior of the structure. 


This will give you the exact number of bales you will need to build the structure.

NEVER Build Your Straw Bale House with the Exact Number!

We never recommend anyone try to build a bale house by only ordering the EXACT number of bales calculated as needed! Always add at least 10% to the total number you just calculated to have extra bales on hand.

And it is worth noting that while this calculator is more accurate than the Basic Method, it doesn’t quite take into account every nuance of any custom needs around how you plan to stack your bales, i.e., deck or balloon framed, or custom bale shaping needs, such as rounded walls.

Try to get as close as possible to the “real answer,” but don’t skimp just to save a few dollars, especially if the bales are less-than-ideal building quality. Learn more about choosing straw bales for construction here. At about $5 a bale, buying a few extras will not hurt nearly as much as running out and delaying the job while you try to locate good quality bales of the same size in order to finish the build. 

You can always use any extras in your garden as mulch, create landscape seating, or even use the straw bales in landscape walls to create privacy or cut down on road noise. A little foundation, mesh, and plaster, and your scrap bales become a thing of beauty in the backyard! We love the creative side of straw bale building as much as we love the technical know-how!

Try out the Straw Bale House Calculator below to take another step forward on building your bale vision!