The Rental Property Calculator Pack

Six calculators for deciding whether a rental works, in the order you need them. Sheet 1 is the one that matters most: the four reserve lines a quick rent-minus-mortgage sum leaves out, which are the difference between a deal that works and one that works until the roof goes. Sheet 5 shows you both versions side by side. Every formula was recalculated and checked against an independent implementation before this shipped.

What is in it

6 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.

- NOI and reserves — What does the property actually net before the mortgage?

- Debt and coverage — What does the loan cost, and will a lender fund it?

- Cap rate and return — What return is this, and why do two people disagree about it?

- The 1% rule, tested — Does the rule of thumb still work at today's rates?

- Counted two ways — What do reserves do to a deal that looks positive?

- Rate sensitivity — What happens to this deal if rates move?

Every formula was checked

This pack contains 30 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 30

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:

- Reserves are averages. A roof does not arrive on schedule.

- A 30-year amortisation. A shorter term raises the payment and lowers DSCR without changing the property at all.

- Cap rate ignores financing entirely -- by definition, not by oversight.

- Reserves counted. Without them the rule looks fine far longer, which is why it survived.

- Nothing differs between the columns except honesty.

- Rent is held constant as the rate moves, which is pessimistic over a long hold and realistic over a short one.

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, 6 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.