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ADU Cost Calculator

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An Accessory Dwelling Unit (ADU) is an increasingly popular way to add more living space to your property. Whether it's for renting out, housing a family member, or simply increasing your property's value, building an ADU comes with its set of financial considerations. That's where an ADU Cost Calculator comes into play. This handy tool helps homeowners estimate the cost of building an ADU on their property, making the planning process much clearer and more manageable.

Purpose and Functionality

The primary purpose of an ADU Cost Calculator is to provide a rough estimate of the total cost involved in constructing an accessory dwelling unit. The calculation takes into account various factors, including the base cost per square foot, the total square footage of the ADU, and any extra features that might enhance the dwelling but add to the cost.

The formula used for calculating the cost is as follows:

Cost = (BaseCostPerSquareFoot * SquareFeet) + ExtraFeaturesCost

  • Cost: Total estimated cost of the ADU.
  • BaseCostPerSquareFoot: Average cost per square foot for building an ADU, including materials and labor.
  • SquareFeet: Total square footage of the planned ADU.
  • ExtraFeaturesCost: Cost of additional features not included in the base price, such as high-end finishes or specialized roofing.

For a more accurate estimation, the calculator also considers the sum of all individual extra feature costs, which might include items like premium flooring, solar panels, or custom windows.

Step-by-Step Examples

Let's consider a practical example to see how the calculator works:

  • Suppose the base cost per square foot in your area is $150.
  • You plan to build a 500-square-foot ADU.
  • You want to add premium flooring and a custom kitchen, totaling an extra $10,000 in costs.

Using the formula, the calculation would be:

Cost = (150 * 500) + 10,000 = $85,000

This means the estimated total cost for your ADU, with the specifications mentioned, would be $85,000.

Relevant Information Table

Here is a table with some hypothetical data to give you an idea of how varying factors affect the total cost:

Base Cost per Sq FtSquare FeetExtra Features CostTotal Estimated Cost


The ADU Cost Calculator is a valuable tool for anyone considering adding an accessory dwelling unit to their property. It provides a clear, easy-to-understand estimate of the costs involved, helping homeowners make informed decisions. By considering the basic construction costs along with any extra features, the calculator ensures there are no financial surprises down the road. With this tool, planning your ADU project becomes a straightforward process, allowing you to focus on the exciting aspects of expanding your living space.

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