Build Cost Calculator
Generate BCIS-aligned construction cost estimates with regional adjustments, contingencies, and professional fees. Essential for development appraisals.
Project Size
Enter the gross internal area and building height
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About the Build Cost Calculator
What it does and how it helps you
The Build Cost Calculator helps UK property developers estimate construction costs using BCIS-aligned benchmarks. Calculate accurate build costs including regional adjustments, contingencies, and professional fees for new builds, conversions, refurbishments, and extensions.
How It Works
Understanding the calculation method
The Build Cost Calculator provides BCIS-aligned construction cost estimates for UK property developments. Whether you're planning a new build, converting commercial space to residential, or undertaking a major refurbishment, accurate cost estimation is critical to your project's viability.
Understanding Construction Costs
Build costs vary significantly based on four key factors:
1. Build Type: New construction, conversions, refurbishments, and extensions each have different cost profiles. New builds require complete structure and services; conversions work within existing shells; refurbishments upgrade existing space.
2. Specification Level: Basic social housing spec starts around £1,200-1,650/sqm. Standard mid-market residential ranges £1,550-2,100/sqm. Premium high-end specification can exceed £2,500-3,000/sqm.
3. Regional Location: UK construction costs vary dramatically by region. London commands 25% premium over Midlands baseline. South East adds 10%, while the North is typically 5% below baseline.
4. Building Height: Projects over 4 storeys incur additional costs for structural engineering, scaffolding access, and construction logistics. Each additional storey typically adds 2-3% to base costs.
How This Calculator Works
Our Build Cost Calculator guides you through a systematic estimation:
1. Project Size: Enter your Gross Internal Area (GIA) in sqm and number of storeys. GIA includes all internal floor space—this is what you're building and paying for.
2. Build Type: Select from new build, conversion, refurbishment, or extension. Each has calibrated base costs reflecting typical construction requirements.
3. Specification & Region: Choose your finish level and location. The calculator applies BCIS regional multipliers and specification adjustments.
4. Fees & Contingency: Add contingency (typically 7.5-15%) and professional fees (10-15%). These are essential but often underestimated costs.
Understanding BCIS Data
BCIS (Building Cost Information Service) is produced by RICS and provides the UK's most comprehensive construction cost database. Our calculator aligns with BCIS median rates for residential development, adjusted quarterly.
Current market factors affecting costs include: - Labour shortages in specialist trades - Material price inflation (particularly steel, concrete, timber) - Energy cost impacts on manufacturing - Supply chain disruptions
What's Included in Build Costs
Typical all-in construction costs cover:
- Substructure: Foundations, groundworks, drainage - Superstructure: Frame, floors, roof, external walls - Finishes: Internal walls, ceilings, floor finishes - Services: Electrical, plumbing, heating, ventilation - External Works: Landscaping, parking, boundary treatments
What's NOT Included
Your build cost budget should be separate from: - Land acquisition costs - Stamp duty land tax - Finance costs (interest, fees) - Sales and marketing costs - Developer profit
Contingency Best Practices
Contingency covers unknowns and variations. Industry guidance:
- New Build (straightforward): 5-7.5% - New Build (complex): 7.5-10% - Conversion: 10-12.5% - Refurbishment: 12.5-15% - Heritage/Listed: 15-20%
Lenders will stress-test your appraisal at higher contingency levels, so budget conservatively. Remember: unused contingency becomes profit.
Professional Fees Breakdown
Total professional fees typically run 10-15% of build costs:
- Architect: 3-5% (RIBA stages 1-7) - Structural Engineer: 1-2% - MEP Consultant: 1-2% - Quantity Surveyor: 1-2% - Project Manager: 2-3% - Planning Consultant: 0.5-1% - Building Control: 0.5-1% - CDM Coordinator: 0.25-0.5%
Complex schemes or tight programmes may require higher professional fees for increased design coordination.
Cost Control Tips
1. Get Early QS Advice: A quantity surveyor during feasibility prevents costly surprises later.
2. Value Engineering: Review specifications against budget early. Premium finishes in common areas; standard in apartments often makes sense.
3. Fix Your Contract: Design and Build with a fixed price provides cost certainty. Traditional contracts with Bills of Quantities offer more flexibility but less certainty.
4. Monitor Inflation: Build costs are rising 3-5% annually. Allow for inflation over your build programme.
5. Phase Where Possible: Phased builds reduce peak debt and allow profit recycling.
When to use this calculator
Use this calculator during feasibility stage to estimate construction budgets for development appraisals. Essential for calculating profit on cost, structuring development finance, and determining residual land value. Use when comparing different build types, specification levels, or regional locations.
Frequently Asked Questions
Common questions about this calculator