Amount, rate, term, first payment: the monthly payment and a full schedule where interest is computed month by month from the balance, rounded to cents like a lender, so every figure is visible. Pro adds extra payments with payoff date and interest saved, a rate-and-term comparison grid, and a formulas walkthrough.
Inputs, PMT, total interest and total paid, and up to 480 rows of date, payment, principal, interest, interest to date and balance. Stops itself at zero; year-end rows shaded. Pro: monthly extra and one-off extras per row, with payments made, interest saved, months saved and payoff date.
Monthly payment and total interest for your amount across five rates (editable) and five terms, with your rate highlighted.
Twelve formulas explained — PMT, the month-by-month interest, why the last payment lands on exactly zero.
Every workbook is recalculated in LibreOffice and by a second, independent formula engine on the sample data; the totals are compared with numbers worked out outside any spreadsheet, and every formula cell is scanned for errors. We don't run Excel itself on the build machine, so this says built for, not tested in — open the live preview to see the numbers the formulas produce.
What that means app by app: in Google Sheets, in Apple Numbers, in LibreOffice Calc.
The home page and its CSS — enough to publish a one-pager. A credit link stays in the footer.
Every page, the Pro-only pages, the source files, no attribution, and 12 months of updates and email support.
Use it for unlimited personal and commercial purposes, including client work.
Do not resell the spreadsheet itself, alone or in a bundle.
Excel’s IPMT gives the right number and no idea why. Principal computes each month’s interest from the previous balance — balance × rate ÷ 12, rounded to cents, the way a lender does — and the payment is capped at what’s owed, so the last row lands on exactly 0.00 instead of leaving three cents behind. Every row is a formula you can follow.
Type a monthly extra, or a one-off in any month’s Extra column, and the schedule shortens. The summary shows payments made, interest paid, interest saved against the scheduled loan, months saved and the payoff date. The Compare sheet lays your amount across five rates and five terms — payment in one grid, total interest in the other — with your rate highlighted.
The build recalculates the workbook in LibreOffice and in a second engine, runs an independent amortization in Python with the same rounding, and compares thirteen values — the payment, the payoff month with extras, total interest, the zero on the last row — against the workbook. If any drift, the file doesn’t ship.
First release
List your debts, pick snowball or avalanche, type the extra you can pay each month: the payoff order, the interest per month and the months each debt takes on its minimum alone. Pro runs the whole payoff month by month — the extra rolls from each paid-off debt to the next — with payoff dates and total interest. No macros.
A week of trading, one row a day: card, cash, how much of it carried VAT, and how many people came in. Takings, the VAT already inside those sales and the spend per head are calculated. Pro adds the month's running costs with a budget, a variance and an On plan / Watch / Over status on every line, plus a summary that reads the week back to you. No macros.
Thirteen weeks across, cash in and out down: the balance carries forward, weeks below your buffer turn red, and the lowest point and its week are found for you. Pro fills the grid from a dated list of expected receipts and payments and shows what's still outstanding from past weeks. No macros.