HELOC Payoff Planner Spreadsheet — Month-by-Month Amortisation, Payoff Date & Interest Saved Calculator (Excel + Google Sheets)

Four numbers in — balance, APR, current payment, extra payment — and this planner builds you two complete month-by-month schedules, calculated row by row the same way your lender calculates them: interest on the beginning balance, payment applied, balance carried forward. One schedule pays exactly what you're paying now. The other adds your extra payment. The summary puts the difference in plain dollars: payoff date each way, total interest each way, months sooner debt-free, and exactly how much interest the extra payment saves you. If a payment is too small to cover a month's interest, the planner shows that honestly instead of inventing a payoff date — which is itself worth knowing.

What's included: HELOC-Payoff-Planner.xlsx (Excel; imports cleanly into Google Sheets); Planner sheet — 4 inputs + full comparison summary (all formulas); Schedule — With Extra (360 formula-driven monthly rows); Schedule — No Extra (360 rows); a plain-language note on variable rates and interest-only draw periods — re-run it whenever your APR changes. No macros.

Who it's for: homeowners with a HELOC balance who want a payoff date, not a guess.

This workbook is for general education and personal organization only. It is not financial, tax, legal, or investment advice.