The HELOC Calculator Pack — Seven linked calculators, every formula checked by recalculation

Seven calculators for a home equity line of credit: the payment jump when the draw period ends, how big a line your equity supports, the interest-only payment, total interest, what a rate rise does, what extra payments save, and a HELOC against a cash-out refinance. Start with sheet 1 -- in the worked example a $50,000 balance goes from $354.17 to $433.91 a month when repayment starts. Every rate is illustrative, not a market rate; type in the ones from your own offer. This is not financial advice. Every formula was recalculated and checked against an independent implementation before this shipped.

What is in it

7 calculators, one per sheet. Overwrite the blue cells with your own numbers and everything else follows — nothing is locked, there are no macros, and it opens in Excel, Numbers, LibreOffice and Google Sheets.

• The payment jump — How much will your HELOC payment jump when the draw period ends?
• Available credit — How big a line of credit could your home equity support?
• Interest-only payment — What is the monthly payment while you are only paying interest?
• Total interest — What will the HELOC cost in interest from first draw to last payment?
• If the rate rises — What happens to your payment if the variable rate goes up?
• Extra payments in the draw — How much interest do extra principal payments during the draw save?
• HELOC vs cash-out refi — Which costs less in total: a HELOC on top of your mortgage, or a cash-out refinance?

Every formula was checked

This pack contains 51 formulas. Before it was published, every one of them was recalculated by a spreadsheet engine and compared against an independent implementation of the same arithmetic written in Python. All 51 agreed to within a cent, and the workbook carries a Verification sheet saying so.

That is an unusual thing to be able to claim about a spreadsheet, and it is the main reason to buy this one rather than download a free template. A formula that looks right and is wrong is worse than no formula at all, because you will act on it.

What each calculator assumes

There is a sheet listing this, because a calculator that hides its assumptions is just a number generator:

• The rate stays the same into repayment (sheet 5 tests a rise). Payments amortize to zero over the repayment period. Some lines require a lump-sum or a different schedule; your agreement governs.
• The lender's limit is the only constraint modeled. Credit score, income and debt-to-income ratio also decide how much is offered.
• The balance stays the same all month and all draw period. Lenders may set a minimum payment above interest-only; your statement shows it.
• The full amount is drawn on day one and held through the draw period, interest-only. The rate never changes. Fees and closing costs are not included.
• The new rate applies to the whole balance and stays there. Periodic caps, floors and the index your rate follows are in your agreement and are not modeled; only a lifetime cap is.
• Nothing is redrawn after it is repaid. The extra payment goes to principal at the end of each month, and the balance must stay above zero for the whole draw -- the check row says so. Same rate throughout.
• Both routes are held to the end of their terms with no prepayment and no rate change; the HELOC figures come from sheets 3 and 4. Totals cover different lengths of time. Closing costs are paid in cash, not rolled into the loan. Taxes, insurance and the time value of money are not counted.

What this is not

Not financial, tax or legal advice, and not a recommendation to buy, sell, borrow or sign anything. These are calculators: they show what a choice costs, not which choice is right for you. Where a published rate or threshold is used it is the one current when the pack was built — those change, the arithmetic does not.

Honest about the format

One .xlsx workbook, 7 calculator sheets plus Start Here, Assumptions and Verification. Not a PDF, not a physical product, not a Notion template. Available immediately after purchase; nothing ships.

Refunds

If this isn't what you expected, email me within 30 days and I'll refund you in full — no need to explain. Because it's an instant download I can't take the file back, so I'd rather you just had your money back.