Principal and interest for self-amortizing and balloon loans, with optional taxes, insurance, PMI and HOA. Every figure updates as you type.
Loan Details
$
%
Loan structure
Self-amortizing loans are fully repaid by the end of the term. Balloon loans mature earlier and leave a lump sum outstanding.
Taxes & insurance
Adds escrow to the monthly payment. Principal and interest figures never change when you switch this on.
Escrow & monthly costs
$
$
$
$
Monthly paymentThe level payment that repays principal and interest. Escrow is added when the toggle is on.
$2,528.27
Principal & interest
Annual payment
$30,339.29
Total interestTotal interest paid over the term. For a balloon loan this tile shows the payoff due at maturity instead.
$510,178.27
Over 30 years
Mortgage constantAnnual debt service as a percentage of the loan amount. Compare it against a property's cap rate.
7.585%
Principal paid
$400,000
Over the term
Payments made
360
Monthly instalments
Where the first payment goes
Early payments are almost entirely interest. The split shifts month by month as the balance falls.
Equity and balance over the loan
Equity built is the principal repaid to date; the balance is what still has to be refinanced or repaid.
Compare against another interest rate
%
Payment at current rate$2,528.27
Payment at comparison rate$2,334.29
Monthly saving$193.98
Smaller balance at maturity
A lower rate pays principal down faster, so it also leaves a smaller balloon. That difference is part of the saving.$0
Total saving over 30 years$69,832.80
Show full amortization schedule
Full amortization schedule with annual subtotals
#
Date
Payment
Interest
Principal
Balance
Annual subtotals shown in bold.
How it is calculated
PMT = P × [ r(1 + r)ⁿ ] ÷ [ (1 + r)ⁿ − 1 ]
The level payment that retires a loan over n periods when each period charges interest r on the balance outstanding at its start. Because the balance falls every month, the interest share of each payment falls with it and the principal share rises — which is why a mortgage pays down slowly at first and quickly at the end.
PMT The level monthly payment of principal and interest.
P Principal — the amount borrowed at closing.
r Periodic interest rate: the annual rate divided by 12.
n Number of payments in the amortization: years × 12.
A worked deal example
A borrower buys a small mixed-use building for $500,000 with 20% down, financing $400,000 at 6.500% on a 30-year amortization with a 7-year term. Property taxes run $6,000 a year and insurance $1,800.
Loan amount
$400,000
Interest rate
6.500%
Amortization
30 years
Term
7 years
Annual taxes
$6,000
Annual insurance
$1,800
Principal and interest come to $2,528.27 a month. Escrow adds $500 of tax and $150 of insurance, so the borrower actually writes a check for $3,178.27 — 26% more than the number most calculators show. The lender still underwrites the $2,528.27. After seven years the loan has only paid down to about $360,000, because the payment was sized across thirty years and not seven. That $360,000 balloon is the number to plan for: it has to be refinanced or repaid, and its size depends far more on the amortization negotiated than on the term.
Frequently asked questions
What is the difference between P&I and PITI?
P&I is principal and interest — the payment that repays the loan itself, and the only part the lender computes from your rate and amortization. PITI adds property taxes and insurance, which the lender collects monthly and holds in escrow until the bills come due. PITI is what leaves your bank account; P&I is what pays down the debt. This calculator defaults to P&I and adds escrow only when you switch the toggle on, so the loan figures never move when you are experimenting with tax estimates.
Why is my payment sized on the amortization instead of the loan term?
Because a balloon loan is deliberately structured that way. A seven-year term on a thirty-year amortization means you pay as though the loan will run thirty years, then hand back whatever is left at the end of year seven. Sizing the payment on the seven-year term instead would roughly triple it and leave no balloon at all. If you want no balloon, set the structure to self-amortizing and the term and amortization become the same number.
How much does the amortization change my payment?
A great deal, and far more than most borrowers expect. On $400,000 at 6.500%, a 30-year amortization costs about $2,528 a month, a 25-year about $2,700, and a 20-year about $2,982. Shortening the amortization raises the payment but cuts total interest sharply and leaves a much smaller balloon. On a commercial deal the amortization is often more negotiable than the rate, and it moves the numbers more.
What is a mortgage constant and why do lenders quote it?
The mortgage constant is annual debt service divided by the original loan amount, expressed as a percentage. It bundles rate and amortization into a single number you can compare directly against a property’s cap rate. When the cap rate exceeds the constant, the loan is accretive — leverage improves your cash-on-cash return. When the constant exceeds the cap rate, borrowing more actually reduces your return, which is the arithmetic behind negative leverage.
Does this calculator include PMI?
Yes, as an optional monthly figure inside the escrow section. Private mortgage insurance typically applies to residential loans above 80% loan-to-value and usually falls away once you reach roughly 20% equity, so it is normally a temporary cost rather than a permanent one. Enter the monthly premium your lender quotes; the calculator does not attempt to predict when it will drop off, because that depends on your servicer’s rules and whether you request removal.
Why does my lender’s payment differ by a few dollars?
Usually the day-count convention. This calculator solves the payment on a level 30/360 basis, which is how nearly all residential and most commercial loans are quoted. Some commercial lenders accrue interest on Actual/360, which charges roughly 365/360 of a year’s interest and produces a slightly different schedule — see the amortization schedule tool for that. Rounding rules and whether your first payment covers a partial month also account for small differences.
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