A full period-by-period schedule with real day-count conventions, stub interest from your closing date, annual subtotals and a CSV you can hand to a lender.
Loan Terms
$
%
Day-count convention
30/360 treats every month as 30 days. Actual conventions accrue on real calendar days, which is what most commercial lenders write.
Monthly paymentSolved on a level 30/360 basis, which is how lenders quote it, regardless of the accrual convention.
$13,818.23
Principal & interest
Annual constantAnnual debt service as a percentage of the loan amount.
8.291%
Balloon at maturity
$1,587,515.69
Due in year 10
Stub interestInterest from the closing date to the start of the first full period. Usually collected at closing.
$6,000.00
16 days
Total interest
$1,245,703.35
Over the term
Maturity date
10/1/2036
Interest and principal by year
The crossover — where principal overtakes interest — is the point a loan starts building equity in earnest.
Balloon under 30/360
The same quoted payment under each convention. The difference is the convention, not rounding.$1,561,541.73
Balloon under Actual/360$1,587,515.69
Cost of the convention at maturity$25,973.97
Show full amortization schedule
Full amortization schedule with stub period and annual subtotals
#
Date
Days
Payment
Interest
Principal
Balance
Stub row first, annual subtotals in bold, balloon last.
How it is calculated
Interest = Balance × Rate × (Days ÷ Basis)
Each row accrues interest on the balance outstanding at the start of the period, for the days that period actually contains, over the convention’s basis. The payment stays level, so whatever the interest does not consume reduces principal — and as the balance falls, the interest share falls with it.
Balance Principal outstanding when the period begins.
Rate The nominal annual interest rate.
Days Days in the period: a flat 30 under 30/360, or the real calendar count under Actual conventions.
Basis Days in the convention’s year — 360 for 30/360 and Actual/360, 365 for Actual/365.
A worked deal example
A $2,000,000 loan closes on 15 September 2026 at 6.750%, on a 25-year amortization with a 10-year term, accruing Actual/360 as most commercial lenders quote.
Loan amount
$2,000,000
Interest rate
6.750%
Amortization
25 years
Term
10 years
Closing date
15 Sep 2026
Convention
Actual/360
The level payment is solved on a 30/360 basis at $13,818.23, which is how the term sheet quotes it. But interest accrues on real days: the borrower owes 16 days of stub interest at closing — 15 September through 30 September inclusive — before the first full period even begins. Across the year, Actual/360 charges roughly 365/360 of what 30/360 would, so the balance falls slightly more slowly than the payment implies. Switch the convention toggle and the balloon at year ten moves from $1,561,542 to $1,587,516 — nearly $26,000 more owed at maturity on the identical quoted payment. That is not a rounding artifact; it is the convention doing exactly what it was written to do.
Frequently asked questions
What is the difference between 30/360 and Actual/360?
Under 30/360 every month is treated as exactly 30 days and every year as 360, so each payment accrues an identical amount of interest for a given balance. Under Actual/360 interest accrues on the real number of days in each period — 31 in a long month, 28 or 29 in February — but still divided by a 360-day year. Because a calendar year has 365 days, Actual/360 collects roughly 365/360, about 1.4% more interest annually, on the same quoted rate.
Why does my balance not reach zero under Actual/360?
Because the payment is solved on a 30/360 basis while interest accrues on actual days. The extra interest each year has to come out of the principal share, so a level payment sized for 30/360 does not quite retire the loan over the amortization. The residual is real and appears in your payoff statement, so this schedule reports it rather than absorbing it into the final row. If your lender quotes Actual/360, expect a small balance at the end of the stated amortization.
What is stub interest and when do I pay it?
Stub interest covers the gap between your closing date and the start of the first full accrual period. If you close on 15 September and regular accrual begins 1 October, you owe 16 days of interest — the 15th through the 30th inclusive, since interest accrues from the closing day itself. Lenders normally collect it at closing out of your funding rather than adding it to the first payment, which is why it belongs in your closing costs and not your monthly budget.
Is the payment based on the term or the amortization?
On the amortization, always. A ten-year term on a twenty-five-year amortization pays as though the loan will run twenty-five years, then matures and demands whatever balance is left as a balloon. This is why lengthening the amortization lowers the payment but leaves a much larger balloon to refinance, and why the amortization is often the more valuable thing to negotiate.
Why do the annual subtotals matter?
They are what your accountant and your lender actually ask for. Interest paid in a calendar or loan year is a deductible expense for an investment property, and the year-end balance is what a refinancing lender will size against. Reading them off a 300-row schedule is error-prone, so this tool inserts a bold subtotal row after every twelfth payment and carries the same figures into the CSV export.
Can I use this for a loan that has already been running?
Yes — set the closing date to the original funding date and the schedule will reproduce the loan from the beginning, including the stub period. Find the row matching your next payment number and its balance column is your current payoff before that payment. If you have made extra principal payments, this schedule will run ahead of your real balance, since it models level payments only.
Estimates only. This calculator is an educational tool, not
financial advice, a loan offer, or a commitment to lend. Actual payments,
loan sizing and closing costs depend on your lender's underwriting, the
day-count convention in your loan documents, and fees not modelled here.
Confirm any figure with your lender or advisor before acting on it.
By Dave Morgan· Commercial Real Estate Finance & Investment Specialist
Updated