Cash flow
How much does an ADU rent for? Build a defensible comp set
A repeatable method for estimating ADU rent using comparable units, consistent costs, and conservative assumptions instead of an automatic new-build premium.
Planning information only. Confirm local requirements and review financing, tax treatment, scope, and costs with the appropriate professionals.
An ADU's potential rent depends on the local market and the unit itself. A new finish, private yard, or parking space may matter to tenants, but none guarantees a premium over an apartment. The original article's individual rent example is no longer presented as a current market benchmark.
Start with comparable units
Collect recent listings close to the property. Record the date, source link, asking rent, bedrooms, bathrooms, approximate size, condition, parking, outdoor space, access, and included utilities. Include comparable ADUs where available, but do not discard apartments that compete for the same tenants.
Asking rents are not signed leases. Remove duplicate listings and flag listings that linger or offer concessions. A local property manager may be able to explain which asking prices are realistic and what information is unavailable.
Compare the same costs
A unit with utilities included is not equivalent to one where the tenant pays them separately. Record concessions and mandatory charges rather than comparing the headline prices alone. Note differences you cannot reasonably price, such as privacy or a difficult access path, instead of inventing a precise adjustment.
Keep a simple worksheet with one row per comparable unit. Add a final column for why it belongs in the set and another for differences from the planned ADU. If the best-looking comp is also the least similar unit, it should not set your expected rent.
Choose a range and document your judgment
Set a conservative case as well as an expected case. Explain why each is supported by the comparables. Avoid averaging several poor matches into a number that looks authoritative. When evidence is thin, label the uncertainty and seek local input before increasing your construction commitment.
HUD Fair Market Rents provide broader context. HUD describes them as area-level estimates used in housing programs, generally based on 40th-percentile gross rents. They are not quotes for a particular ADU.
Rent is not monthly cash flow
Allow for vacancy, turnover, management, repairs, owner-paid utilities, insurance, and financing. Check rental rules with the local authority and avoid assuming short-term rental income will be permitted. An unoccupied unit still has expenses.
Read why monthly rent is not the answer to turn the comp set into a cash-flow comparison. Refresh the comps when your schedule changes; the evidence gathered before design may no longer describe the market at completion.