What is a Commercial Mortgage Calculator and How Does It Work?
A commercial mortgage calculator is an essential tool for commercial real estate investors to estimate their monthly loan payments and total borrowing costs. Our commercial mortgage calculator 2026 uses standard amortization formulas and the 365/360 US Rule to provide accurate payment estimates. The commercial loan calculator helps investors model cash flow, compare loan options, and plan for balloon payments at maturity.
How does the commercial mortgage payment calculator work? Enter the loan amount, interest rate, loan term, amortization period, and rate method. The commercial real estate mortgage calculator instantly shows your monthly payment, total interest, total payments, and balloon payment at maturity. The commercial property mortgage calculator also calculates the effective interest rate under the 365/360 US Rule.
Commercial vs Residential Mortgages: Key Differences
Commercial mortgages differ from residential mortgages in several important ways:
Loan Terms: Residential mortgages typically have 15-30 year terms that match the amortization. Commercial mortgages have shorter terms (5-10 years) with longer amortization (25-30 years), resulting in a balloon payment at maturity .
Interest Calculation: Most commercial loans use the 365/360 US Rule, which calculates interest using a daily rate based on a 360-day year but charges interest for the actual number of days in each month. This results in a higher effective interest rate than the nominal rate .
Underwriting: Commercial lenders focus on the property's income (NOI) and debt service coverage ratio (DSCR), not just the borrower's credit. Most require a minimum DSCR of 1.25x to 1.35x .
Balloon Payments: Because commercial loan terms are shorter than amortization, a substantial balloon payment is due at maturity — often 50-70% of the original loan balance .
The 365/360 US Rule Explained
The 365/360 US Rule is the standard interest calculation method for most commercial mortgages. Here's how it works :
Daily Rate: Nominal annual rate ÷ 360 days = daily interest rate
Monthly Interest: Outstanding balance × daily rate × actual days in month (28-31 days)
Because interest is charged for 365 days per year but calculated using a 360-day divisor, the effective annual rate is higher than the nominal rate. For example, a 6.00% nominal rate results in an effective rate of approximately 6.09% under the 365/360 US Rule .
Our commercial mortgage calculator includes both the standard monthly rate method and the 365/360 US Rule. Select the method used by your lender for accurate results.
How to Calculate Commercial Mortgage Payments
The standard amortization formula for monthly payments is:
PMT = P × [r(1+r)^n] / [(1+r)^n - 1]
Where:
- P = Loan principal
- r = Monthly interest rate (annual rate ÷ 12)
- n = Total number of payments (amortization years × 12)
Example: $1,000,000 loan at 6.5% with 25-year amortization:
- Monthly rate: 6.5% ÷ 12 = 0.5417%
- Number of payments: 25 × 12 = 300
- Monthly payment: $6,752
Our commercial mortgage calculator does this math instantly for any loan amount, rate, and amortization period.
Understanding Balloon Payments
The most important thing to understand about commercial mortgages is the balloon payment. Because the loan term (5-10 years) is shorter than the amortization period (25-30 years), the loan is not fully paid off when the term ends. The remaining principal balance is due in full at maturity .
For example, a $1,000,000 loan at 6.5% with a 10-year term and 25-year amortization:
- Monthly payment: $6,752
- Balance after 10 years: approximately $800,000
- Balloon payment due: $800,000
Investors must plan for this balloon payment by either refinancing, selling the property, or using other capital sources. Our commercial loan calculator shows your estimated balloon payment so you can plan accordingly.
Commercial Mortgage Loan Options in 2026
Commercial real estate investors have several financing options:
Bank/Portfolio Loans: 5.75% – 7.5% | 5-10 year terms | 25-30 year amortization | 75% max LTV. Best for stabilized properties with strong sponsors.
CMBS/Conduit Loans: 6.0% – 7.5% | 10-year terms | Non-recourse | 75% max LTV. Best for larger loans ($5M+) seeking non-recourse structure.
Life Company Loans: 5.71% – 7.98% | 5-30 year terms | 65-70% max LTV. Best for institutional-quality assets in major markets.
SBA 504/7(a) Loans: 5.9% – 9.75% | Up to 25-year terms | Up to 90% LTV. Best for owner-occupied properties.
Bridge Loans: 8% – 15% | 6-36 month terms | Interest-only | Up to 80% LTC. Best for value-add and transitional properties.
Why Use Our Commercial Mortgage Calculator?
Our free commercial mortgage calculator is built for accuracy and simplicity. It runs entirely in your browser — no sign-up, no data stored. The commercial real estate loan calculator supports both standard amortization and the 365/360 US Rule used by most commercial lenders. Whether you're evaluating an acquisition, refinancing an existing loan, or comparing lender quotes, our commercial property mortgage calculator delivers professional-grade results in seconds.