CPI Rent Indexation Calculator

CPI-indexed rent tracks inflation subject to floor/ceiling constraints.

Base rent

CPI change %

Floor %

Ceiling %

Adjusted rent

$501,600

Effective change %

0.04%

Dollar increase

$21,600

How the math works

Effective = max(floor, min(ceiling, CPI)). Adjusted = base × (1 + effective).

CPI 4.5% sits in 2%-5% collar → effective 4.5%. $480k × 1.045 = $501.6k adjusted rent. $21.6k increase.

How to Use

Enter base rent.
Enter CPI change %.
Enter floor %.
Enter ceiling %.
Read adjusted rent.

Frequently Asked Questions

CPI mechanics?

Base rent × (1 + CPI change). Subject to floor (min) and ceiling (max) constraints. Common floor: 2%; common ceiling: 5%. CPI-U (urban) most common index; some leases use regional or CPI-W.

Why floors and ceilings?

Floors protect landlord from deflation or flat CPI — guarantees minimum rent growth. Ceilings protect tenant from runaway inflation — 2022-23 proved the point, when CPI hit 8-9% but ceilings capped at 5%, saving tenants millions.

Collar example?

2%/5% collar: if CPI 1%, rent grows 2% (floor). If CPI 7%, rent grows 5% (ceiling). If CPI 3.5%, rent grows 3.5% (unconstrained). Collars balance inflation protection for both parties.

What documentation matters here?

Written leases, move-in/move-out inspections with photographs, ledger entries showing every payment and charge, served notices with proof of service, and contemporaneous emails or texts. Courts weigh written evidence heavily; informal understandings rarely stand. Institutional operators run a monthly file audit to catch gaps before they matter. Good paper trails recover most of what's owed.