Rates & sources
SDLT/LTT/LBTT bands vary between England, Wales, Scotland and Northern Ireland. Use the appropriate calculator.
Source: HMRC / Welsh Revenue / Revenue Scotland — figures refreshed at the start of each tax year.
When to use this calculator
- Before buying, renting, refinancing, or reviewing a property investment.
- When you want to compare cash flow, yield, growth, and ownership costs side by side.
- When you need a fast estimate before speaking to an agent, lender, or adviser.
- When you are assessing whether a rental property still makes financial sense after a mortgage rate change.
- When you want to compare the total cost of renting against owning over a five- or ten-year horizon.
A realistic New Zealand planning example
Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.
Property Price (NZ$)
NZ$750,000
Deposit (NZ$)
NZ$150,000
Mortgage Rate (%)
NZ$600,000
Term (Years)
25 years
After entering these figures, review mortgage, rent and difference together rather than in isolation — each metric tells a different part of the story. Then rerun the tool with one input adjusted to see which variable has the biggest effect on all three outputs before you settle on a plan.
How to read your results
Mortgage
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Rent
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Difference
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Method & assumptionsAuthoritative sources
This calculator computes the monthly repayment mortgage payment on a capital-and-interest (repayment) basis using the standard annuity formula, then shows the difference against the monthly rent figure you enter. The mortgage payment is derived from the loan amount (property price minus deposit), the annual interest rate entered, and the mortgage term in years.
The comparison is a cash-flow snapshot only. It does not capture the equity built through capital repayment each month, any property value appreciation, the opportunity cost of the deposit if invested elsewhere, or the one-off purchase costs (Stamp Duty Land Tax, legal fees, survey). In the UK, SDLT applies on residential purchases in England and Northern Ireland; Scotland uses Land and Buildings Transaction Tax (LBTT) and Wales uses Land Transaction Tax (LTT), each with its own rate bands. These costs typically add 2–5% to the purchase price and should be factored into any genuine rent-vs-buy analysis over a realistic holding period of five years or more.
Common mistakes
- !Comparing rent and ownership costs without including taxes, fees, and maintenance.
- !Using purchase price alone without testing the impact of financing or vacancy assumptions.
- !Relying on yield or growth in isolation instead of reviewing the full property case.
- !Forgetting Stamp Duty Land Tax (or its Scottish and Welsh equivalents), which can add thousands to the true cost of purchase.
- !Using optimistic rental growth figures without also testing a flat or declining rent scenario to check downside resilience.
What to do next
- Run a second scenario with a higher rate or lower rental yield to check downside resilience.
- Compare the result with a buy-versus-rent or stamp duty calculator before making an offer.
- Use the related guides below to understand agent fees, legal costs, and ongoing maintenance budgets.
- If you are assessing a buy-to-let, check the gross yield against the net yield after mortgage interest, voids, and management fees.
- Note down the key figures from this scenario to share with your solicitor or mortgage broker so they are working from the same assumptions.
Frequently asked
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End-of-article next steps
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