Mortgage & Loan Payoff Calculator
See exactly what an extra payment is worth: five loans, full 360-payment schedules, and extra-payment, biweekly, refinance and lump-sum comparisons in one Excel / Google Sheets file.
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- 15 sheets · 31357 formulas
- Formats: .xlsx (Excel 2016+, Google Sheets) + PDF guide
- ZIP: 438 KB
Set it up, use it for at least a week, and if it genuinely isn't right for you, send us a message within 14 days with a screenshot of your setup and we'll refund you in full.
Most payoff calculators give you one amortisation table and leave you to guess. This one answers the question you actually have: what happens if I pay a bit more? Put in up to five loans — mortgage, car, student, credit card, personal — and the workbook builds a full 360-payment schedule for each, runs the same loan again with no extra payments, and shows you the gap between the two.
Four separate sheets price the four real ways to finish early. Extra Payment What-If runs your loan eight times at eight different extra amounts — eight complete schedules, no goal-seek and no macros — so you can see the payoff date and total interest for $25, $50, $100 and up. Biweekly vs Monthly prices the thirteen-payments-a-year trick and tells you when it is not worth paying a lender for. Refinance Comparison gives you the break-even month for the closing costs and the lifetime cost, which is where a lower monthly payment over a longer term gets caught. Lump Sum Impact tests the same windfall at year 1, 3, 5 and 10.
Everything is built on one interest convention held across all 15 sheets — monthly rate = APR ÷ 12, interest on the opening balance, PMT for the scheduled payment, final payment trimmed to land exactly on zero — so the comparisons are like for like. Every schedule was checked against an independently written Python model before release: payment, payoff month, total interest and interest saved all match. On the sample mortgage ($320,000 at 6.25% over 30 years) an extra $250 a month clears the loan 92 months early and saves $115,679 in interest.
It ships pre-filled with five realistic loans so every chart and schedule is alive when you open it — clear the yellow cells in about a minute and make it yours. Built only with functions Google Sheets supports (PMT, EDATE, INDEX/MATCH, SUMIF, CHOOSE), so it behaves identically in Excel 2016+, Excel 365 and Google Sheets, on desktop and phone.
What you get
- 15 sheets, 31,357 formulas — no macros, no add-ons, nothing locked
- Up to 5 loans at once, each with a full 360-payment amortisation schedule
- Every schedule runs twice — with your extra payments and without — so "interest saved" and "months saved" are real, not estimated
- Extra Payment What-If: eight extra amounts, eight complete schedules, payoff date and interest for each
- Biweekly vs Monthly: what 13 payments a year is worth, and how to get the same result free
- Refinance Comparison: new payment, break-even month for the fees, and the lifetime cost trap
- Lump Sum Impact: the same windfall tested at year 1, 3, 5 and 10
- Dashboard with 8 KPIs (payment, debt-free date, months saved, interest saved, total interest, total cost, home equity, owed today) and 4 charts
- Payoff Tracker: a 100-block map showing the payment number you clear every 1% on, plus ten milestone dates
- 120-row Payment Log, one-off extra payments, any currency symbol, Google Sheets instructions PDF included
Preview every page
Click any page to zoom.
What's inside
Questions
Does it work in Google Sheets?
Yes. Upload the .xlsx to Google Drive, open it and choose File → Save as Google Sheets. Every formula uses functions Sheets supports — PMT, EDATE, INDEX/MATCH, SUMIF, COUNTIF, CHOOSE, ROUND. There are no macros, no XLOOKUP and no dynamic arrays. It is a large file (five 360-row schedules), so the first open in Sheets can take fifteen or twenty seconds; after that it is quick. The included PDF walks you through it.
Will the numbers match my lender exactly?
Very closely, but expect small differences. The workbook uses the standard monthly convention: monthly rate = APR ÷ 12, interest = opening balance × that rate, rounded to the cent. Many lenders accrue interest daily instead, which typically shifts a thirty-year total by a few dollars and never changes the conclusions. Use it to compare options, not to reconcile a statement to the penny.
My mortgage payment includes escrow and insurance. What do I enter?
Enter only the principal-and-interest part. Escrow for property tax and insurance is collected alongside the loan payment but never touches the balance, so including it would make the payoff look faster than it is. Your statement usually breaks the two apart.
I am ten years into my loan. Does that work?
Yes — that is the normal case. Enter the original amount and original term (which is what sets your scheduled payment) plus the balance you owe today. The schedule starts from today's balance, so it finishes in the time you actually have left, not the original thirty years.
What if I have fewer than five loans?
Leave the spare rows on Loan Inputs blank. Their amortisation sheets stay empty, the totals ignore them and nothing breaks. There is no way to add a sixth loan without restructuring the file — email us and we will send you an extended version free.
Is it really sample data I can delete?
Yes. Five loans for a fictional household are pre-filled in the yellow input cells only, so the charts and schedules work the moment you open the file. Select A6:J10 on Loan Inputs and press Delete, then A7:G18 on the Payment Log. Formulas, dropdowns and charts stay intact. The PDF lists every range.
Does it handle a lump sum, or only monthly overpayments?
Both. Each loan on Loan Inputs takes a one-off extra payment with a date alongside its monthly extra, and the Lump Sum Impact sheet tests the same windfall at four different timings so you can see how much the date matters.
Is this financial advice?
No. It is a calculator. It cannot know about early-repayment penalties in your loan agreement, an employer pension match you are missing, or whether you would be better off investing the money. Check those before you overpay anything.
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Personal-use license for one household. No resale or redistribution. Delivered as a ZIP download immediately after payment. No physical item will be shipped.
