Buy-to-Let Calculator
Model yield, cash flow and returns on a single buy-to-let property.
Introduction
Who this is for: First-time and experienced landlords assessing a single rental property purchase.
Why it matters: Purchase price and headline rent tell you very little on their own — financing cost, void periods and running costs determine whether a property is actually profitable.
Typical scenario: An investor is comparing a £220,000 two-bed flat against a £180,000 terraced house, both let at similar rents, and needs a like-for-like return comparison.
- Using gross yield alone to compare properties, ignoring costs entirely.
- Forgetting to stress-test the mortgage against a higher interest rate.
- Excluding void periods and management fees from cash flow projections.
Inputs
Purchase
Finance
years
Rental
Running Costs
Analysis
A net yield of 4.5% is within, or slightly below, the typical UK regional average of 4-6% for comparable assets.
The property is projected to generate positive monthly cash flow of £61 after all costs and mortgage interest.
Rent would need to fall to approximately £1,019 per month before the deal breaks even on cash flow.
This analysis provides context, not financial advice. Consult a qualified adviser before making investment decisions.
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Sensitivity
Adjust the variables below to stress-test this scenario. Results update instantly.
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Glossary
- Gross Yield
- Annual rent divided by purchase price, before any costs are deducted.
- Net Yield
- Annual rent minus running costs, divided by purchase price.
- DSCR
- Debt Service Coverage Ratio — net operating income divided by mortgage interest. Lenders use this to assess affordability.
- Void Period
- Time the property sits empty between tenancies, during which no rent is collected.
Frequently Asked Questions
What deposit do I need for a buy-to-let mortgage?
Most lenders require a minimum 25% deposit for buy-to-let, though some products allow 20% at a higher interest rate.
Is buy-to-let mortgage interest tax-deductible?
Since April 2020, individual landlords in the UK receive a tax credit at the basic rate (20%) on mortgage interest rather than deducting it from taxable income. This calculator shows pre-tax cash flow — consult an accountant for your specific position.
What void allowance should I use?
A conservative allowance is 4-8% of the year, reflecting typical re-letting periods between tenancies.
Live Results
Gross Yield
6.00%
Net Yield
4.46%
Monthly Cash Flow
£61
Return on Cash Invested
1.20%
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