How Do I Calculate Effective Interest Rate in Excel

Analyze monthly payments, balloon totals, and loan-to-value ratios.

Loan Summary

Total Loan Amount:
$0.00

Loan-to-Value (LTV):
0%

Monthly Payment (P&I):
$0.00

Total Interest Paid:
$0.00

Balloon Payment (End of Term):
$0.00

Understanding Commercial Real Estate Financing

Commercial real estate (CRE) loans differ significantly from residential mortgages. While a home loan is typically amortized and termed for 30 years, commercial loans often feature shorter terms with "balloon" payments.

Key Commercial Loan Metrics

• Loan-to-Value (LTV): Most commercial lenders require an LTV between 65% and 80%. A higher down payment reduces risk for the lender and may secure a better interest rate.
• Amortization vs. Term: The amortization is the period used to calculate the monthly payment (e.g., 25 years). The term is how long the loan actually lasts (e.g., 10 years). At the end of the term, the remaining balance is due as a balloon payment.
• Debt Service Coverage Ratio (DSCR): Lenders use this to see if the property's income covers the debt. Usually, a DSCR of 1.25x or higher is required.

Example Calculation

If you purchase an office building for $1,000,000 with $250,000 down (75% LTV) at a 6.5% interest rate, amortized over 25 years with a 10-year term:

• Monthly Payment: Approximately $5,064.
• Balance after 10 years: You would owe a balloon payment of roughly $584,000.
• Strategy: Most investors refinance or sell the property before the balloon payment becomes due.

function calculateCRE() { var price = parseFloat(document.getElementById('propPrice').value); var down = parseFloat(document.getElementById('downPayment').value); var rate = parseFloat(document.getElementById('interestRate').value); var amort = parseInt(document.getElementById('amortYears').value); var term = parseInt(document.getElementById('loanTerm').value); if (isNaN(price) || isNaN(down) || isNaN(rate) || isNaN(amort) || isNaN(term) || price <= 0) { alert("Please enter valid positive numbers for all fields."); return; } var loanAmt = price – down; if (loanAmt 0) { monthlyPayment = loanAmt * (monthlyRate * Math.pow(1 + monthlyRate, numPaymentsAmort)) / (Math.pow(1 + monthlyRate, numPaymentsAmort) – 1); } else { monthlyPayment = loanAmt / numPaymentsAmort; } // Balloon Payment Formula: Remaining Balance // B = P[(1+i)^n – (1+i)^p] / [(1+i)^n – 1] var balloon = 0; if (term 0) { balloon = loanAmt * (Math.pow(1 + monthlyRate, numPaymentsAmort) – Math.pow(1 + monthlyRate, numPaymentsTerm)) / (Math.pow(1 + monthlyRate, numPaymentsAmort) – 1); } else { balloon = loanAmt – (monthlyPayment * numPaymentsTerm); } } else { balloon = 0; } var totalPaidOverTerm = monthlyPayment * numPaymentsTerm; var principalPaidOverTerm = loanAmt – balloon; var interestPaidOverTerm = totalPaidOverTerm – principalPaidOverTerm; // Formatting document.getElementById('resLoanAmt').innerText = "$" + loanAmt.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('resLTV').innerText = ltv.toFixed(2) + "%"; document.getElementById('resMonthly').innerText = "$" + monthlyPayment.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('resInterest').innerText = "$" + interestPaidOverTerm.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('resBalloon').innerText = "$" + balloon.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('resultsArea').style.display = 'block'; }