Calculating legally compliant rent late fees across U.S. states
8 comments
·October 20, 2025hrgdevBuilds
I built a small tool to clarify how much late fee a landlord can legally charge (and when) in each U.S. state.
Rent laws vary widely: some states set a fixed dollar cap, others a percentage, and a few use only “reasonable” language that’s open to interpretation. Many renters and landlords have no easy way to check what’s actually allowed without reading the statutes themselves.
This project compiles those laws into an instant calculator. Enter rent amount, due date, payment date, and state — it shows the lawful late fee limit, grace period rules, and citation.
It started as a curiosity after seeing conflicting answers online. The goal is transparency, not advocacy; all data is drawn from current state statutes.
The app is lightweight, built in Replit, and runs entirely client-side. I’d be interested in feedback on legal interpretation consistency, data sourcing, or UI clarity.
limagnolia
Utah appears to be calculating incorrectly, the text says "10% of rent or $75, whichever is GREATER." But it is doing the opposite, showing the lessor of 10% or $75.
limagnolia
New Hampshire has the same bug.
axus
I love the ambiguity in who the tool is for. For renters, learning about their rights and fighting illegal fees. For landlords, charging the maximum amount permitted under the law.
limagnolia
Or landlords who want to follow the law, but aren't sure what it is, trying to make sure they are doing things right.
candiddevmike
I thought this would be for tenants, but this seems more geared towards landlords. Most landlords have some kind of SaaS platform that will automate all of this for them as part of rent collection, I don't think you'll get many bites on this TBH.
I'd love to see some kind of 50 state tenant resource center, geared towards providing tenants with advice and legal resources.
josefritzishere
Sounds like a great tool. But it's sad that it needs to exist.
Curious what your process for gathering and verifying the legal information was