Property Deal Calculator for
Flips, BRR & Buy-to-Let

A property deal calculator helps investors quickly assess whether a potential property purchase is financially viable. It takes your purchase price, refurbishment costs, expected end value, and rental income, then calculates key metrics like profit, return on investment (ROI), and cash left in the deal across different strategies.

Flip profit is calculated by taking the post-refurbishment value (also called the Done Up Value or DUV) and subtracting all costs involved: the purchase price, stamp duty, legal fees, sourcing fees, refurbishment costs, contingency, and miscellaneous holding costs. The result is your gross profit on the deal.

BRR (or BRRR) stands for Buy, Refurbish, Rent, Refinance. It is a strategy where you buy a property below market value, refurbish it to increase its value, rent it out, then refinance onto a standard mortgage based on the new higher value. This can allow you to recycle your initial capital into the next deal.

Investment properties in the UK attract the higher rate of Stamp Duty Land Tax (SDLT). As of April 2025, the higher rates are: 5% on the portion from £40,001 to £125,000, 7% from £125,001 to £250,000, 10% from £250,001 to £925,000, 15% from £925,001 to £1.5 million, and 17% above £1.5 million. Properties below £40,000 usually do not attract higher rates.

Key costs to include are: the purchase price, stamp duty (SDLT), legal and conveyancing fees, property sourcing or finder's fees, refurbishment costs, a contingency buffer (typically 10% of refurb), and miscellaneous holding costs such as insurance and utilities during the refurb period. This calculator includes all of these.

ROI shows the return you are getting on the cash you have tied up in the deal. Gross yield compares the annual rent with the property value or purchase price before mortgage and management costs. Gross yield is useful for comparing deals quickly, while ROI gives a better sense of how hard your cash is working.

This calculator uses UK-standard assumptions: 10% contingency on refurb costs, 4% mortgage interest rate (interest only), 75% loan-to-value on refinance, 10% lettings management fee, £50 per month miscellaneous costs during refurb, and 25% deposit for the standard buy-to-let scenario. Stamp duty uses the current higher rates for additional properties.