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.
Purchase Price (NZ$)
NZ$0.30
Renovation Cost (NZ$)
NZ$500
Agent & Legal Fees (NZ$)
35
Sale Price (NZ$)
NZ$0.30
After entering these figures, review profit, total cost and roi 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
Profit
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.
Total Cost
This is the headline outcome of the calculation, but it is most useful when read alongside the supporting metrics below it rather than in isolation. Try changing one input at a time and watching how this total moves to understand which driver has the biggest impact.
ROI
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 estimates gross profit on a property flip by subtracting total costs from the anticipated sale price. Total cost is the sum of purchase price, renovation spend, and agent fees entered. Return on investment is then expressed as profit divided by total cost, as a percentage. This gives a quick sense of whether a project meets your minimum return threshold before committing capital.
The calculator does not include Stamp Duty Land Tax, finance costs (bridging loan interest and arrangement fees), legal fees on purchase and sale, or Capital Gains Tax — all of which are material on a real transaction. For a property held as an investment property rather than a main residence, the 3% SDLT surcharge for additional dwellings applies in England. If HMRC treats the flip as a trading activity rather than a capital disposal, income tax and National Insurance may apply instead of CGT. Users should add these costs manually and consult a tax adviser before committing to a project.
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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