Most buy-to-let calculators tell you a deal is profitable. They don't tell you the lender is about to decline it.
This one does both.
Put in the price, the rent, the mortgage and your running costs. It gives you the honest numbers — and then it runs the deal through the same stress test your lender will.
WHAT IT WORKS OUT
Gross yield — on the purchase price, and on the total project cost
Net yield — after your running costs
Cash flow — monthly and annual, after costs and mortgage interest
Cash-on-cash ROI — the return on the money you actually put in
Break-even rent — the point at which cash flow hits zero
Sensitivity — what happens if rent drops 10%, or rates rise 2%
THE LENDER STRESS TEST
The stressed monthly payment, at a rate above the one you'll pay
The minimum rent the lender needs to see
Your headroom, in pounds
A straight PASS or FAIL
This is the part most people miss. Lenders don't lend on yield — they test the rent against an interest coverage ratio, usually 145% for a higher-rate taxpayer or 125% for a basic-rate taxpayer or limited company. A deal can look profitable and still be refused. Both cells are editable, so you can test the exact ratio your lender applies.
WHAT YOU GET
One Excel file (.xlsx), works in Microsoft Excel and Google Sheets
Yellow input cells — you only fill in what's yours
All rate cells editable, so it doesn't go out of date
Instant download
Built to show the downside as clearly as the upside. If a deal doesn't work, this will tell you.
Educational tool only. Not financial, mortgage, tax or legal advice. Figures and assumptions correct as of July 2026 — always confirm rents, costs and lending criteria before you commit to anything.
Most buy-to-let calculators tell you a deal is profitable. They don't tell you the lender is about to decline it.
This one does both.
Put in the price, the rent, the mortgage and your running costs. It gives you the honest numbers — and then it runs the deal through the same stress test your lender will.
WHAT IT WORKS OUT
Gross yield — on the purchase price, and on the total project cost
Net yield — after your running costs
Cash flow — monthly and annual, after costs and mortgage interest
Cash-on-cash ROI — the return on the money you actually put in
Break-even rent — the point at which cash flow hits zero
Sensitivity — what happens if rent drops 10%, or rates rise 2%
THE LENDER STRESS TEST
The stressed monthly payment, at a rate above the one you'll pay
The minimum rent the lender needs to see
Your headroom, in pounds
A straight PASS or FAIL
This is the part most people miss. Lenders don't lend on yield — they test the rent against an interest coverage ratio, usually 145% for a higher-rate taxpayer or 125% for a basic-rate taxpayer or limited company. A deal can look profitable and still be refused. Both cells are editable, so you can test the exact ratio your lender applies.
WHAT YOU GET
One Excel file (.xlsx), works in Microsoft Excel and Google Sheets
Yellow input cells — you only fill in what's yours
All rate cells editable, so it doesn't go out of date
Instant download
Built to show the downside as clearly as the upside. If a deal doesn't work, this will tell you.
Educational tool only. Not financial, mortgage, tax or legal advice. Figures and assumptions correct as of July 2026 — always confirm rents, costs and lending criteria before you commit to anything.
