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CalculatorByState

Extra Payment & Early Payoff Tracker

$9.99

A live 360-month amortization schedule that recalculates as you change your extra payment — showing the months you cut off the loan, the interest you never pay, and an honest side-by-side against investing the same money instead.

Format: Excel (.xlsx)

Look inside

Preview only — scroll to read it. The file you download is fully editable.

Read-only preview of the Payoff Tracker worksheet
Extra Payment & Early Payoff Tracker
Fill in the blue cells and the full month-by-month schedule below recalculates — including your new payoff date, the months you cut off the loan, and the interest you never pay. The log at the bottom is yours to check off as you actually make the extra payments.
Part 1 — Your loan
Current loan balance320000
Interest rate (%)6.65Enter as a number, e.g. 6.65 — not 0.0665.
Years remaining30
Scheduled monthly principal & interestƒxYour required payment. Taxes and insurance are excluded — extra payments go to principal, and this worksheet is only about principal and interest.
Part 2 — Your extra-payment plan
Extra amount added every month200Any amount. Even $50 a month moves the payoff date meaningfully on a 30-year loan.
One-time lump sum5000A bonus, tax refund, or windfall.
Apply the lump sum in month #61 = immediately. The earlier a lump sum lands, the more interest it prevents.
Part 3 — What it saves you
Original payoff — monthsƒx
New payoff — monthsƒxCounted from the full schedule below (Part 6, row 63) — the number of months in which you actually make a payment.
Months savedƒx
Years savedƒx
Interest paid WITHOUT extra paymentsƒx
Interest paid WITH extra paymentsƒx
Total interest savedƒxThe headline number — money that stays with you instead of going to the lender.
Part 4 — Or invest it instead?
Paying down a mortgage earns you a guaranteed return equal to your interest rate. Investing the same money might earn more, or might earn less — it is not guaranteed. This is the honest comparison, with the assumption you choose highlighted in yellow so you remember it is an assumption and not a pro…
Assumed annual investment return (%)7Yellow because this is the one number here nobody actually knows. Try a pessimistic value too and see whether the answer changes.
Value if you invested the extra monthly amount insteadƒxThe same monthly amount, invested over the same number of months, at the return rate above.
Guaranteed saving from prepaying (interest avoided)ƒx
Difference (investing − prepaying)ƒxPositive means investing came out ahead AT THE ASSUMED RATE. Remember the mortgage saving is certain and the investment return is not.
Part 5 — Your payment log
Check off each extra payment as you actually make it. The schedule to the right assumes you make every one — this column is how you keep the model honest against real life.
MonthDate paidExtra amount actually paid
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21

Preview shows the first 60 rows. The full worksheet continues for 374 more — the complete month-by-month schedule is in the download.

This template is general information, not financial, legal, or tax advice.