Amortization Calculator

How this result is built

Build a yearly or monthly amortization schedule and see how extra principal changes interest.

Amortization is the order in which a fixed payment retires a balance. Early payments are mostly interest because the balance is large. Later payments flip toward principal. The yearly view adds twelve months so you can read a 30-year loan without scrolling through 360 lines.

What the opening example is for

Extra principal does not change the formula. It changes the balance the next interest charge is based on. A steady extra amount is usually more powerful than a single round-up, because it repeats.

The walkthrough below uses the numbers already sitting in Amortization Calculator. Press Calculate and the headline should match this page. Then put your own figures in. The math does not run until you press the button, and Clear hides the result.

What each field is doing

The “Loan amount” line on Amortization Calculator starts at $320,000.00. Leave that figure only when it matches the statement, the quote, or the plan you are testing. Press Calculate after the edit so the chart and the schedule move with it.

Amortization Calculator treats “Interest rate” as its own entry, and the form opens with 6.25%. A round example is useful for learning the page. It is a poor substitute for the number on your own paperwork, so replace it and run the form again.

The remaining fields

Before you replace it, “Term” reads 30 on Amortization Calculator. The other fields stay put while you change this one. That is the clean way to see what this line is doing inside the result.

Look at “Extra principal per month” first if you are checking Amortization Calculator: the filled value is $100.00. If the label is a rate, type the annual figure the contract uses. If it is money, type the amount that will actually move, not a rounded hope.

The opening result, line by line

Press Calculate on the opening form and Monthly payment is $2,070.30. That is the number the rest of this section is talking about.

Amount financed is $320,000.00 when you run the opening figures on Amortization Calculator. That line is part of the same calculation as the headline. It is not a second balance you can spend on top of the result. Change one input and press Calculate if you want to see whether this line moves.

On this opening pass, base payment is $1,970.30. That line is part of the same calculation as the headline. It is not a second balance you can spend on top of the result. Change one input and press Calculate if you want to see whether this line moves.

Amortization Calculator reports that total interest is $331,577.59. That line is part of the same calculation as the headline. It is not a second balance you can spend on top of the result. Change one input and press Calculate if you want to see whether this line moves.

How those lines were produced

Total paid is $651,577.59 when you run the opening figures on Amortization Calculator. That line is part of the same calculation as the headline. It is not a second balance you can spend on top of the result. Change one input and press Calculate if you want to see whether this line moves.

On this opening pass, payoff time is 26 years 3 months. That line is part of the same calculation as the headline. It is not a second balance you can spend on top of the result. Change one input and press Calculate if you want to see whether this line moves.

An extra $100.00 each month changes the payoff to 315 months.

A second pass changes only “Loan amount”, from $320,000.00 to $352,000.00. Monthly payment moves from $2,070.30 to $2,267.32. Nothing else on the form was edited, so the gap between those two results is the effect of that one field on Amortization Calculator. If the gap is tiny, this page is not very sensitive to that entry. If the gap is large, get that entry from a document before you plan around the result.

What this page will not claim

Amortization Calculator does not know your credit score, the county’s tax bill, or what an appraiser will say. Type the price, the loan, and the escrow you were quoted. Compare the payment with the loan estimate, and treat a small rounding difference as normal.

Amortization Calculator stops at its own formula. When the next question is different, open Mortgage Calculator (Principal, interest, tax, insurance, PMI, and HOA in one payment.); Extra Payment Calculator (One extra amount, every month, on any fixed loan.); Loan Calculator (A fixed payment, a rate, and the interest it creates.). Do not add those results to this one as if they were the same kind of dollar.

Check the result before you use it

Start on Amortization Calculator by reading the labels, not the headline. The opening labels are Loan amount ($320,000.00), Interest rate (6.25%), Term (30), Extra principal per month ($100.00). If a label is not the fact you have, the result cannot turn into that fact later. The illustration on the form lands on $2,070.30. When you press Calculate and see that same figure, the button and this explanation are using one formula.

Change one field at a time. Write down the headline, edit a single line, and press Calculate again. A large jump means that line carries the result. A line that does not move is a line the formula ignores, which is a reason to confirm you opened the right page. Amortization Calculator is built for one job: A schedule that shows where each payment goes. The description on the page says the same thing in a sentence: Build a yearly or monthly amortization schedule and see how extra principal changes interest.

When the paperwork disagrees

Then hold the headline next to a source outside the site. That source might be a loan estimate, an account statement, a pay stub, or the public limit named in the methodology. A few cents of difference on a long schedule is ordinary rounding. A different rate, a fee you never typed, or a tax the form does not ask for is not rounding. Correct the input. Do not average the page with the paperwork.

When the outside source still disagrees, Amortization Calculator has reached the edge of what it will claim. It will not phone a lender, pull a county record, or apply a credit you left blank. Send the calculator name, every input, and the result you expected through the contact page if you think the formula itself is wrong. Until that is settled, read $2,070.30 as the output of the fields above and nothing else.

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