Renovation Budget Estimator

This calculator gives a realistic per-square-metre budget for refurbishing your home, from a cosmetic refresh through to a full structural strip-out. It uses UK industry rules of thumb across three rough depth levels and adds a contingency line — the bit nobody plans for and nearly every project needs.

It matters because renovation is the area where homeowners most consistently underestimate cost. Pinterest boards and showroom kitchens hide a long tail of expenses — site protection, skips, waste disposal, electrical first fix, plastering, snagging — that don't appear in the headline figure but routinely add 15–25% to the bill.

It's most useful very early in planning, when you're deciding whether a project is even viable, or comparing two homes (one cheaper but needing work, one move-in-ready). It's least useful as a contract figure — for that, you need itemised quotes from two or three trades against a scoped specification.

A worked example

Refurbishing 80m² of a Victorian terrace to a mid-level standard — new kitchen, new bathroom, redecoration throughout, replaced flooring, electrics and plumbing brought up to current standards — typically runs at around £1,400/m², or £112,000 base cost. Add a 15% contingency and the realistic budget is closer to £128,000. The same 80m² as a light cosmetic refresh might be £48,000 with contingency; a full structural strip-out can comfortably exceed £200,000.

Why this matters

Setting a realistic budget at the start is the single biggest predictor of whether a renovation finishes on time and on speaking terms. Underbudgeted projects don't stop — they stall, lose momentum, and end up costing more because trades have to be re-booked at short notice. A budget with a real contingency line is what allows you to say yes to a sensible change-order without renegotiating the whole project.

Common mistakes

• Setting the contingency at 5% on an older property — 15–20% is the realistic floor for anything pre-1970.
• Forgetting professional fees (architect, structural engineer, party-wall surveyor, planning, building control) — typically 10–15% on top.
• Underestimating VAT — most labour and materials carry 20% in the UK, and a VAT-registered contractor will pass it through.
• Choosing finishes (kitchen, tiles, sanitaryware) after the budget is fixed; specification creep is the most common overspend.
• Treating one informal quote as "the price" without an itemised, scoped specification to compare like-for-like.

Beyond the numbers

The cost of a renovation is only half the question — the other half is the cost of the disruption. A six-month project means six months of rented kitchens, takeaways, dust, and decisions. For larger projects, factor in temporary accommodation (or a serious patience reserve) and the cost of putting essentials into short-term storage. Sequencing matters too: doing the electrics, plastering and floors before the kitchen goes in is far cheaper than chasing wires through new walls. A short paid hour with a builder or architect at the planning stage to sanity-check the order of works pays for itself many times over. For specific surfaces, the Paint Calculator, Tile Calculator and Flooring Calculator turn the per-m² figure into specific material quantities.

Related tools: Extension Cost · Paint Calculator · Tile Calculator · Flooring Calculator