US residential tenancy is governed almost entirely by state statute, and the notice period a tenant owes is written into each state's landlord-tenant code. There is no single federal rule setting the number of days, though federal law does frame the edges: the Fair Housing Act (42 U.S.C. §§ 3601-3619) shapes how landlords may respond, and the Servicemembers Civil Relief Act gives service members an early-termination right that overrides ordinary notice requirements. Everything else comes down to the state where the property sits.
For month-to-month tenancies, the baseline in most states is 30 days. California codifies this in California Civil Code § 1946, which lets either party end a month-to-month tenancy on at least 30 days' written notice, while § 1946.1 extends the landlord's obligation to 60 days once a tenant has lived in the unit for a year or more. A subtle and tenant-friendly wrinkle sits in Civil Code § 1953: any lease clause forcing a tenant to give more than 30 days' notice is void as against public policy, so a landlord cannot bind you to a 60-day tenant notice by contract. Texas takes a rent-period approach under Texas Property Code § 91.001, where a month-to-month tenancy ends one month after notice is given, or at the end of the current rent-paying period, whichever is later. Florida is the outlier tenants most often get wrong: Florida Statutes § 83.57 requires only 15 days to end a month-to-month tenancy, not 30. New York, since the Housing Stability and Tenant Protection Act of 2019, ties the period to length of occupancy under Real Property Law § 226-c, requiring 30 days under a year, 60 days from one to two years, and 90 days beyond two years.
Read the statute that matches your state before you pick a move-out date, because a notice that is a few days short is often treated as no notice at all. The federal government's plain-language overview of these rules, published by HUD in its state-by-state tenant rights and protections resource, is a reliable starting point before you check your local code.