Commercial Loan Balance Calculator

Commercial loans commonly combine an interest-only period (1-5 years), followed by amortization on a 25-30 year schedule, with a balloon at a 5-10 year term. This calculator projects the balance at any month given the structure so you can model refi, sale, or YM scenarios accurately.

Loan amount

Rate

Amortization (years)

Interest-only months

Balance at month

$3,710,487

Cumulative interest through month

$1,571,062

Interest-only payment

$19,167

Amortizing payment

$23,343

How the math works

$4M loan at 5.75% / 30-year am with 24-month IO. At month 84 (7 years): balance $3.73M (vs $3.51M if fully amortizing from month 1). The 24 IO months 'cost' you ~$220K of principal paydown you didn't do.

Use this for refi sizing and YM calculations. Get to month 84 balance, plug into YM calculator with current treasury — that's your true exit cost.

How to Use

Enter loan amount, interest rate, amortization years, and interest-only months.
Enter the month at which you want the balance (for balloon, use balloon month).
See balance and cumulative interest at that month.

Frequently Asked Questions

How common are IO periods?

Very. Most CMBS and agency loans include 12-36 months IO; bank loans often 0-12 months. IO boosts early cash-on-cash returns but delays principal paydown. Full-term IO is aggressive; typically only top-tier properties qualify.

Does IO affect balloon balance?

Significantly. IO months don't reduce principal, so balance at balloon = original amount minus principal paid only during the amortizing period. A 60-month IO on a 30-year am 10-year-balloon loan means you start amortizing at month 61 and only pay down for 60 months before balloon — leaving a big balance.

25 vs 30 year amortization?

30 lowers monthly payment ~10%; 25 pays down faster. For a property hold of 5-10 years, the difference in balloon balance can be meaningful ($50K-$200K on larger loans). Negotiate 30 if you're cash-flow sensitive, 25 if you're equity-building.

How do I know if a loan is amortizing now?

Check your latest statement — if principal reduction is showing each month, you're past the IO period. If payment amount is interest × balance, you're still in IO. Statement will usually label it.