California Rent Increase Calculator: AB 1482 Cap, CPI, and Notice Rules

A California rent increase calculator comes down to one formula: the maximum annual increase on a covered unit is the lower of 5% plus your region’s Consumer Price Index change, or 10%, applied to your base rent.¹ You need two numbers to run it, and you need to confirm the law actually reaches your unit before the math means anything.

Step 1: Find Your Base Rent

Base rent is not always what you’re paying today. The statute defines it as the lowest gross rental rate charged for the unit at any point during the 12 months before the increase takes effect. If the landlord dropped the rent at any stage during that window, the lower figure is your base.¹

Concessions are treated differently. Temporary discounts, incentives, credits, or move-in specials that the landlord offered and the tenant accepted are excluded from the calculation. If your lease shows a gross rent of $2,200 with a $200 monthly concession that brings your effective payment to $2,000, your base rent is $2,200. The law requires the gross rent and the concession to be listed separately in the lease exactly so this stays unambiguous.²

Step 2: Find Your Regional CPI Change

The second number is the percentage change in the Consumer Price Index for All Urban Consumers (CPI-U) for your region. The Bureau of Labor Statistics publishes separate CPI data for several California metro areas, including Los Angeles, San Francisco, San Diego, and Riverside.³

Which month of CPI data you pull depends on when the increase takes effect:

Increases taking effect before August 1: use the change between the April CPI from the prior calendar year and the April CPI from the year before that.
Increases taking effect on or after August 1: use the change between the April CPI for the current calendar year and the April CPI from the prior year.

If April data isn’t published for your specific area, use March instead. Round the resulting percentage to the nearest tenth of a percent.² For the period starting August 2025, the Los Angeles area’s maximum allowable increase was 8.0%, reflecting 5% plus a 3.0% CPI change.⁴

Step 3: Run the Formula

Take the lower of these two figures:

5% plus your regional CPI percentage change, or
10%

Multiply the lower percentage by your base rent. That’s the maximum dollar amount your rent can climb in any 12-month period.¹

Example With Moderate Inflation

Base rent is $2,000. Regional CPI change is 3.0%. The formula gives 5% + 3.0% = 8.0%. That’s under 10%, so 8.0% is the cap. Multiply $2,000 by 0.08. The maximum increase is $160 per month, and the new rent cannot exceed $2,160.

Example Where the 10% Ceiling Kicks In

Base rent is $2,000. Regional CPI change spikes to 6.5%. The formula gives 5% + 6.5% = 11.5%, which exceeds the absolute cap. The 10% ceiling applies instead. Ten percent of $2,000 is $200, so the new rent tops out at $2,200. The 10% ceiling exists to prevent runaway increases when inflation surges.⁵

The Two-Increment Rule

Even when the math stays inside the cap, a landlord cannot break the increase into more than two separate raises during any 12-month period. A 3% increase in March followed by a 4% increase in July uses up both allowed increments for that year. A third increase would violate the law, no matter how small, and no matter that the combined total sits below the cap.¹

Does the Cap Actually Apply to Your Unit?

Running the numbers only helps if California Civil Code § 1947.12 reaches your rental. The law covers most residential rentals, including apartments, duplexes, and other multi-family housing where the owner does not live on site. It also covers single-family homes and condominiums owned by a corporation, a real estate investment trust, or an LLC that has at least one corporate member.¹

Several categories fall outside the cap:

Units that received their certificate of occupancy within the last 15 years, on a rolling basis. Mobilehomes don’t get this exemption.
Single-family homes and condos owned individually (not by a corporation, REIT, or corporate-member LLC), but only if the landlord has delivered the specific written exemption notice the statute requires. Without that notice, the cap applies regardless of ownership type.
Deed-restricted affordable housing for very low, low, or moderate-income households.
Dormitories owned and operated by a college, university, or K–12 school.
Units already covered by a stricter local rent control ordinance.

When Local Rent Control Overrides the State Formula

Over 30 California cities and unincorporated Los Angeles County run their own rent stabilization programs. Los Angeles, San Francisco, Oakland, Berkeley, Santa Monica, San Jose, and Beverly Hills all have independent ordinances, and many of them cap increases well below the state formula. Some tie their annual allowable increase to a fraction of the CPI, which can produce caps in the 3% to 5% range.

If your unit falls under a local ordinance that limits increases to less than the state formula would allow, the local rule controls, and the state statute expressly steps aside.² Before you rely on any calculation that uses the 5% + CPI figure, check with your city’s rent board or housing department to see whether a lower local cap governs.

Notice Rules That Can Void the Increase

A correctly calculated increase can still fail on delivery. California Civil Code § 827 requires the notice to be in writing and either handed to the tenant personally or served by mail under Code of Civil Procedure § 1013.⁶

The required lead time depends on the size of the raise, measured against the lowest rent charged in the prior 12 months:

10% or less: at least 30 days’ notice before the increase takes effect.
More than 10%: at least 90 days’ notice.⁶

When the notice is mailed and both addresses are within California, add five calendar days to the notice period. A 30-day notice by mail effectively runs 35 days; a 90-day notice runs 95.⁷ Missing the deadline by a single day can invalidate the increase.

If You’ve Been Overcharged

Section 1947.12(k) lets a tenant sue for the amount of the overpayment, injunctive relief, and, at the court’s discretion, reasonable attorney’s fees and costs. When the landlord acted willfully or with fraud, oppression, or malice, the court can award up to three times the overcharge.²

The statute of limitations is three years from the date of the overcharge. City attorneys and county counsel can also bring enforcement actions, and the statute presumes irreparable harm to the tenant, which makes injunctive relief easier to secure. Any lease clause purporting to waive these protections is void as against public policy.² The California Attorney General’s office suggests contacting a lawyer promptly, and points tenants who can’t afford one to LawHelpCA.org for free legal aid.⁸

1
California Legislative Information. California Civil Code 1947.12
2
California Legislative Information. California Code CIV 1947.12
3
U.S. Bureau of Labor Statistics. Consumer Price Index, Los Angeles Area – April 2026
4
Los Angeles County Department of Consumer and Business Affairs. Rent Increases – Consumer and Business
5
California Department of Justice Office of the Attorney General. The Tenant Protection Act Your Obligations as a Landlord or Property Manager
6
California Legislative Information. California Code CIV 827 – Change of Terms of Lease
7
California Legislative Information. California Code CCP 1013
8
California Department of Justice. Landlord-Tenant Issues