The House Flipping & BRRRR Calculator Pack — Seven linked calculators, every formula checked by recalculation

Seven calculators for a flip or a BRRRR deal, from the offer to the refinance. Start with sheet 2: in the worked example a house bought at the 70%-rule ceiling makes $42,600, not the $90,000 the rule leaves on paper, once buying, financing, holding and selling costs are paid. Sheet 5 shows what comes back at a BRRRR refinance and what stays in the deal. The 70% rule is a rule of thumb and its percentage is an input you set. Every price, rent and rate is an example to overwrite with your own quotes and comparable sales. These are estimates, 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.

• Maximum allowable offer — What is the most to pay for a house you plan to flip?
• Full flip profit — What does the flip actually make after every cost?
• Cost of a month of delay — What does each extra month before the sale cost?
• ROI and annualized return — What return does the flip earn on your cash, per year?
• BRRRR refinance — How much cash comes back at the refinance, and how much stays?
• Cash flow after the refi — Does the rent still cover everything once the new loan is on?
• Profit if things go wrong — How much does a lower ARV, a repair overrun or a delay cost?

Every formula was checked

This pack contains 48 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 48 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 rule percentage is a screening shortcut, not a profit calculation. ARV and repairs are your estimates; an error in either flows straight into the offer.
• The loan is interest-only and fully drawn at purchase; rehab draws, which charge interest only as drawn, would cost less. Income tax on the profit is not included.
• Holding costs stay the same each month. A delay that also forces a lower sale price is sheet 7's job.
• Same profit however long it takes; sheet 3 prices what a delay really takes out of it. Annualized figures assume the cash is redeployed at the same return.
• Your lender sets its own loan-to-value limit, seasoning periods and closing costs; all three are inputs here. A cash-out refinance is a loan, not income -- it still has to be repaid from the rent (sheet 6).
• Repairs and management are set as shares of the full rent. Capital items (roof, HVAC) need their own reserve beyond the repairs share. Income tax and depreciation are not included.
• Each shock is applied on its own and then together; the combined line does not include a lower price caused by the delay itself. Selling costs scale with the sale price.

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.