Why we built this
Most real estate deals should be decided on a single screen of math — yet that math is often buried in clunky spreadsheets or tools that demand an email before they'll show you a number. Ledgerstone exists to give investors that math instantly, with no signup and no friction.
How we calculate
Every calculator uses the standard formulas lenders, appraisers, and experienced investors rely on. The tools run entirely in your browser in transparent JavaScript — nothing you type is sent to a server or stored. The exact formula behind each one is documented below. Methodology last reviewed: June 2026.
Methodology — every formula
| Calculator | Formula |
|---|---|
| Cap Rate | (NOI ÷ price) × 100, where NOI = rent × 12 × (1 − vacancy%) − operating expenses |
| Cash-on-Cash | (annual cash flow ÷ cash invested) × 100; cash invested = down payment + closing costs |
| Rental Property ROI | (cash flow + year-1 principal paydown + appreciation) ÷ cash invested × 100 |
| BRRRR | cash left = (purchase + rehab + costs) − (ARV × refi LTV); cash-on-cash on the cash left in |
| Fix & Flip | profit = ARV − (purchase + rehab + holding + financing + ARV × selling%) |
| 70% Rule | max allowable offer = (ARV × 70%) − repair costs |
| 1% Rule | rent ÷ (purchase + rehab) × 100, compared to a 1% target |
| DSCR | net operating income ÷ annual debt service (monthly PITIA × 12) |
| Hard Money | interest-only payment = loan × rate ÷ 12; total cost = interest + points + fees |
| Airbnb / STR | revenue = nightly rate × (30.4 × occupancy%); cash flow = revenue − operating − fixed costs |
| Reverse Mortgage | proceeds = min(home value, HUD limit) × PLF − existing mortgage − costs |
| Mortgage Recast | re-amortize (balance − lump sum) over the same remaining term at the same rate |
Assumptions & limitations
- Mortgage payments use the standard fully-amortizing formula (principal & interest only; taxes and insurance are entered separately as expenses).
- Percentage inputs (down payment, vacancy, LTV) are clamped to 0–100% to prevent nonsensical results.
- Reverse mortgage uses a simplified principal-limit-factor estimate, not official HUD tables — treat it as a ballpark only.
- Appreciation and occupancy are your assumptions, not forecasts; results are only as good as those inputs.
- Taxes (income, capital gains, depreciation recapture) are not modeled — consult a tax professional.
- Every result is a pre-tax estimate to screen deals; confirm with comparable sales, your lender, and a licensed professional before transacting.
What this is not
Ledgerstone provides educational tools, not financial, tax, legal, or investment advice. Results are estimates meant to help you screen deals quickly. Always verify figures with comparable sales, a licensed professional, and your lender before you transact.
Get in touch
Suggestions for a calculator we should add? Found a number that looks off? Tell us on the contact page — we read everything.