California caps most annual rent increases at 5% plus regional inflation, or 10%, whichever is lower (Civil Code 1947.12). This works out what that means for your rent.
The inflation half of the formula is regional, not statewide. If you do not know your region’s figure, leave it blank and the tool will show you the 10% ceiling instead.
How this tool was built: methodology and sources
The formula is written into statute. Civil Code section 1947.12 limits the annual increase to “5 percent plus the percentage change in the cost of living, or 10 percent, whichever is lower”. The tool computes both and returns the lower one, which is exactly what the statute requires.
The same section limits frequency: rent “shall not be increased in more than two increments over that 12-month period”. Two smaller increases are allowed; using them to exceed the annual cap in total is not.
Why you have to supply the CPI
We do not hard-code an inflation number, because there isn’t one. The cost-of-living component is regional, so the correct figure depends on the metropolitan area your unit sits in, and it is republished annually. Hard-coding a single statewide number would give a confidently wrong answer to most of the state. The California Department of Housing and Community Development and the Department of Justice publish the applicable regional figures.
The cap may not apply to you at all
Section 1947.12 exempts several categories, including deed-restricted affordable housing, student dormitories, housing with a certificate of occupancy issued within the last 15 years (a rolling window), single-family homes and condominiums where the owner is not a corporation or REIT and the required notice was given, and owner-occupied duplexes. Units covered by a local rent control ordinance with a lower cap are governed by that stricter local rule instead — which is the situation in Los Angeles, San Francisco, Oakland, Berkeley, Santa Monica, West Hollywood, San Jose and a number of other cities.
The statute expires
Section 1947.12 states that it “shall remain in effect until January 1, 2030, and as of that date is repealed.” Local ordinances are separate and unaffected by that date. Statute text verified 25 August 2026.
This is not legal advice. It calculates the statewide statutory cap only, and cannot tell you whether your specific unit is exempt or covered by a stricter local ordinance.