How much value does an ADU add?

There is no reliable national figure. An appraiser decides for your property.

Net yearly income divided by property value, used by investors and appraisers.

Do appraisers use rent for ADUs?

Sometimes; often they rely on comparable sales.

Value = (rent × 12 × (1 − vacancy) − yearly costs) ÷ cap rate.

Inputs on this tool, in the order they appear on the form.
Input	What it is actually asking
Cap rate	The yield buyers expect on rental property in your area. Small changes move the result a lot.
Yearly costs	Insurance, repairs, added tax and utilities you pay.

Including one where the naive answer misleads, which is the example most calculators leave out.

Run the same rent at two cap rates. The spread shows how sensitive the result is.

If the income value is far below what the ADU cost, rent alone does not justify the build.

The cap rate has the largest effect. Use a figure from a local professional, not a national average.

Do not use the result for a loan or sale price. See our research on whether ADUs add value.

How much value does an ADU add?: There is no reliable national figure. An appraiser decides for your property.
What is a cap rate?: Net yearly income divided by property value, used by investors and appraisers.
Do appraisers use rent for ADUs?: Sometimes; often they rely on comparable sales.
Is this an appraisal?: No.

Figures dated 27 October 2026. Last reviewed September 16, 2026.