About — Deposit Interest Calculator
Why we built a 50-state security deposit interest calculator, how every number is sourced from state statutes, and how we keep it current.
Deposit Interest Calculator is a free, independent reference for one question that US renters and landlords ask constantly: does my state require interest on a security deposit — and at what rate?
Why this site exists
There is no shortage of generic "compound interest" calculators. What has been missing is a calculator that knows the law: Massachusetts's 5%, Maryland's Treasury-yield formula, states that peg deposit interest to the federal discount rate, and the cities (Chicago and San Francisco among them) that require interest even where the state does not. Every state government publishes its own rules, but no state covers your question if you move — so we built the cross-state layer: one page per state, one formula per state, every number cited.
How we source everything
- Primary source: the state legislature, attorney general, or housing agency itself (.gov wherever possible). Each state page names its statute — for example the exact code section — and links the official text.
- Second source: independent references (attorney-general guides, tenant organizations, established legal publishers) are used to cross-check; where we could not confirm a figure against two sources, we label it "(to be verified)" instead of guessing.
- Last Verified dates: every state page carries the date its figures were last checked. State laws change; when they do, we update the page and move the date.
What the calculators do
The deposit interest calculator applies your state's statutory rate and method (simple or compounded, fixed or benchmark-linked) to your deposit amount and tenancy dates. The rent increase calculator applies your state's cap formula where one exists. Both show their assumptions and both are estimates — not legal advice (see the disclaimer).
Independence
The site is free and supported by advertising and affiliate partnerships with property-management software providers. That does not change our data rules: sources on the page, dates on the data, and the statute always wins.
Questions or corrections: contact page.