Commercial Mortgage Payment Calculator
Estimate monthly payment, annual debt service, loan constant, and term payments for a commercial mortgage.
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How it works
Follow the underwriting path lenders use: input the deal, apply constraints, then read the result.
Enter loan amount
Start with the commercial mortgage balance or proposed loan proceeds.
Commercial Mortgage Payment Formula
Commercial mortgage payments are based on loan amount, interest rate, and amortization. The annual payment divided by loan amount is the loan constant. Learn how the loan constant works before comparing payment coverage.
Read the calculation methodology and limitations.
Monthly Payment = P x [r(1+r)^n] / [(1+r)^n - 1]
Loan Constant = Annual Debt Service / Loan AmountA $10,000,000 loan at 6.50% over 30 years produces annual debt service based on the same amortization math lenders use for DSCR sizing.
See This Calculator in Action
Explore institutional underwriting examples. Load any scenario into the live calculator with one click to customize rates, amortization, and property valuation.
10-year term, 30-year amortization
Monthly Payment = P x [r(1+r)^n] / [(1+r)^n - 1]The payment estimate drives annual debt service, which becomes the denominator in DSCR.
Underwriting Metric Comparison & Lender Sizing Standards
Compare debt yield against DSCR and LTV constraints, and review typical sizing assumptions across lender types.
Payment Inputs and DSCR Impact
3 Core Sizing TestsIncreases debt serviceLowers DSCR
Lowers debt serviceRaises DSCR
Lowers debt serviceRaises DSCR
| Change | Payment Effect | DSCR Effect |
|---|---|---|
| Higher rate | Increases debt service | Lowers DSCR |
| Longer amortization | Lowers debt service | Raises DSCR |
| Lower loan amount | Lowers debt service | Raises DSCR |
Worked examples
| Scenario | Calculation | Result |
|---|---|---|
| Permanent loan | $10,000,000 at 6.50% / 30 years | Monthly payment and loan constant output |
| Higher rate stress | $10,000,000 at 7.50% / 30 years | Higher annual debt service and lower DSCR |
| Shorter amortization | $10,000,000 at 6.50% / 25 years | Higher payment than 30-year amortization |
Conversion reference
| Input | Effect | Metric Impact |
|---|---|---|
| Higher rate | Raises payment | Lowers DSCR |
| Shorter amortization | Raises payment | Lowers DSCR |
| Lower loan amount | Lowers payment | Raises DSCR |
| Higher NOI | No payment change | Raises DSCR |
Quick facts
- Annual debt service is the denominator in DSCR.
- Loan constant converts loan balance into annual payment percentage.
- Commercial loan term and amortization are not always the same.
- Payment estimates are screening outputs, not lender quotes.
Editorial Team
Commercial Real Estate Finance Reviewers
- Calculations reviewed against standard CRE lending formulas for DSCR, LTV, cap rate, and debt yield
- Methodology cross-checked against lender-style loan sizing using NOI, value, loan constant, DSCR, LTV, and debt yield
Our editorial team builds and reviews commercial real estate finance calculators around the way lenders actually size debt: property income, collateral value, annual debt service, and lender risk thresholds. Results are educational screening estimates, not loan quotes, tax advice, legal advice, or a commitment to lend.
Methodology: formulas are calculated from borrower-entered inputs using standard CRE underwriting relationships for NOI, debt yield, DSCR, LTV, cap rate, loan constant, and maximum loan proceeds.
Reviewer note: pages are reviewed for formula accuracy and updated when lender benchmarks or site methodology changes.
Disclaimer: results are educational estimates only and are not financial, legal, tax, valuation, or lending advice.
Frequently asked questions
Use the loan amount, monthly interest rate, and amortization months to calculate the monthly payment, then multiply by 12 for annual debt service.
Loan constant is annual debt service divided by loan amount. Lenders use it to convert debt service capacity into loan proceeds.
Not always. A loan can have a 10-year term and 30-year amortization, which creates a balloon balance at maturity.