Refurb calculator
Property Refurb ROI Calculator UK -- Free
Refurb ROI is the single most-misunderstood number in UK property investing. A £30k refurb that lifts value by £45k looks great until you back out SDLT, bridging interest, contractor overruns, and selling costs -- at which point that 50% headline becomes 12% real money. This free calculator runs the numbers properly. No sign-up, no paywall, results in under a minute.
What does the refurb ROI calculator compute?
Two outputs matter for a refurb: ROI on money in (the cash return) and break-even resale price (the floor below which you lose money). The calculator takes purchase price, refurb budget, SDLT, legal and survey fees, bridging or cash funding profile, holding costs over the works period (insurance, council tax on void, utilities, bridging interest), target Gross Development Value (GDV), and selling costs (agent fee, conveyancing, capital gains or trading income treatment).
From those it produces total money in, net profit on completion, ROI as a percentage of money in, and the resale price at which you exactly break even. The break-even number is the most useful for stress testing: if your target GDV is £185,000 and the break-even is £172,000, you have a 7% cushion before the deal goes negative. If break-even is £181k against a £185k target, you are exposed to any softness in local pricing or a slow sale.
The calculator also separates flip economics (sell at completion, profit taxed as trading income for active flippers) from BRRR economics (refinance and hold, profit is recycled capital rather than realised gain). Most investors mix the two; the Flip calculator handles the sell-at-completion case and the BRRR calculator handles the refinance-and-hold case using the same underlying refurb logic.
UK refurb cost benchmarks -- 2025 working numbers
Use these as a starting point only; always validate with three competitive contractor quotes on a written specification. All figures exclude VAT (most refurb contractors operate at sole trader or limited company below the £90k VAT threshold; if your contractor is VAT registered, add 20%).
Cosmetic refresh (£15-25 per sq ft): paint throughout, new carpets, kitchen door and handle replacement, light fittings, deep clean, garden tidy. Suitable for a tired but functional property where the bones are sound. A typical 850 sq ft terrace runs £13-21k. Timeline: 2-3 weeks.
Light refurb (£40-60 per sq ft): new kitchen (mid-range £5-8k installed), new bathroom (£3-5k installed), full redecoration, new flooring throughout, EICR remedial, gas safety, boiler service or replacement. A typical 850 sq ft terrace runs £34-51k. Timeline: 4-6 weeks.
Medium refurb (£80-110 per sq ft): above plus full rewire, partial replumb, replaster downstairs, new flooring, new boiler, double glazing if needed, garden landscaping. A typical 850 sq ft terrace runs £68-94k. Timeline: 10-14 weeks.
Full gut refurb (£140-180 per sq ft): strip back to brick, structural alterations (knock-throughs, RSJ), new electrics and plumbing throughout, new heating system, replaster throughout, new floors, full external work, loft conversion or side-return extension separately costed. A typical 850 sq ft terrace runs £119-153k. Timeline: 16-26 weeks.
Common refurb ROI mistakes
- 1 Pricing the GDV off asking prices. Asking prices are aspirational. Use SOLD comparables on the same street within the last six months. Land Registry data is free; several paid services aggregate the same data with better filtering. Your refinance valuer will use sold comparables; you should too.
- 2 Underbudgeting contingency. 10% contingency is the minimum on a clean property; 15-20% is realistic on older UK stock. Hidden electrics, damp, joinery, asbestos in textured ceilings (anything pre-2000), and roofing surprises emerge once walls and floors are open. Model the cushion explicitly.
- 3 Forgetting tax on flip profit. If you actively flip, HMRC treats the profit as trading income (subject to income tax at marginal rates plus National Insurance), not capital gains. The headline 30% ROI on the calculator can become 15-18% after tax for higher-rate filers. Speak to an accountant before your first flip.
Run a refurb deal in 60 seconds
Open the Flip or BRRR calculator free, or sign up to Propreneur to attach contractor quotes, track works progress, and bank-feed your refurb spend against the budget.