Mathematical & Statutory Methodology
Detailed mathematical specifications and legal foundations underlying our four rent apportionment models.
Method 1: Actual Days in Month (Primary Standard)
Daily Rate = Monthly Rent ÷ Exact Days in Calendar Month (28, 29, 30, or 31)Prorated Rent = Daily Rate × Days of Lawful Tenancy
This is the most widespread and legally favored formula for residential tenancies. Because each calendar month has an exact known length, dividing by the actual number of days treats each month as an independent financial period. Days of tenancy include both the start and end dates inclusive.
Method 2: Banker's 30-Day Rule
Daily Rate = Monthly Rent ÷ 30.0Prorated Rent = Daily Rate × Days Occupied
Borrowed from corporate debt amortization, the Banker's Rule assumes every month has exactly 30 days. While convenient for long-term bookkeeping, it can produce slight anomalies in February (where 28 days of rent would not equal a full month) and 31-day months.
Method 3: 365-Day Annual Formula
Daily Rate = (Monthly Rent × 12) ÷ 365Prorated Rent = Daily Rate × Days Occupied
Preferred by large corporate REITs (Real Estate Investment Trusts) and institutional property management software (such as Yardi and RealPage). This method calculates the annual lease liability first and divides it across 365 days (or 366 in leap years), providing a completely uniform daily rate regardless of the month.
Method 4: 360-Day Commercial Standard
Daily Rate = (Monthly Rent × 12) ÷ 360Prorated Rent = Daily Rate × Days Occupied
Standard in commercial triple-net (NNN) leases, retail storefronts, and industrial warehouse tenancies.