GDV Calculator

The GDV Calculator is an essential tool for UK property developers assessing the sales value potential of development projects. Gross Development Value (GDV) represents the total revenue your completed scheme will generate—it's the starting point for every development appraisal.

Understanding Gross Development Value

GDV is the sum of all individual unit sales values in your completed development. It's calculated by multiplying floor area (sqft) by achievable price per sqft, then applying any new build premium. Accurate GDV estimation is critical because all other appraisal calculations flow from this figure.

Get your GDV wrong by 10% and your residual land value could shift by 30% or more. Overestimate and you'll overpay for sites. Underestimate and you'll miss viable opportunities.

How This Calculator Works

Our GDV Calculator guides you through a systematic approach to valuation:

1. Location Analysis: Enter your development postcode and property type. Location fundamentally drives pricing—a 2-bed flat in Zone 1 London might achieve £1,000/sqft while the same unit in a northern town might be £250/sqft.

2. Unit Mix Configuration: Define your scheme's unit composition. Add different bedroom types (studios through to 4+ beds), set quantities, and specify typical floor areas. The calculator tracks total units and combined floor area.

3. Price Per Sqft: Set achievable £/sqft for each unit type based on local comparable sales. Larger units typically achieve lower £/sqft than smaller ones. Consider tenure (freehold vs leasehold), floor level, aspect, and specification.

4. New Build Premium: New developments typically command 10-20% premium over equivalent second-hand stock. Buyers pay extra for: NHBC warranty, modern specification, no chain, Help to Buy eligibility, and EPC A/B ratings.

5. AI Market Validation: Our AI analyses your assumptions against Land Registry sold price data, providing comparable sales and market context specific to your postcode.

Key Metrics Explained

- Total GDV: Combined value of all units at your assumed pricing - GDV Per Unit: Average sales value across the scheme - GDV Per Sqft: Achieved price per square foot after premium - Unit Mix Value: Breakdown by bedroom type

Researching Comparable Sales

Accurate GDV requires thorough comparable research:

1. Land Registry Data: Search recent sales (6-12 months) within 0.5 miles. Focus on similar property types and bedroom counts.

2. Adjust for Differences: If a comparable is older, smaller, or lower spec, your new build should achieve more. If it's larger or better located, adjust down.

3. Agent Consultation: Speak to 3-5 local agents about achievable values. They know which developments are selling well and which are struggling.

4. Rightmove Research: Check current new build listings in the area. What's the competition pricing at? How long have units been on market?

5. Sensitivity Testing: Run scenarios at +/- 10% from your base case. How does profit change? Development is risky—build in margin for error.

Common GDV Mistakes

- Assuming Prime Pricing Throughout: Not every unit achieves top values. North-facing, lower floors, and busy road aspects discount 5-15%.

- Ignoring Sales Costs: Remember to deduct 3-5% for agents, legal, and incentives when calculating net GDV.

- Static Market Assumptions: Values change during your 18-24 month build. Current prices aren't necessarily completion prices.

- Optimistic Unit Sizes: Marketing areas (NIA) are what matters for sales. Don't confuse with GIA used for build costs.

Market Context Matters

GDV is market-sensitive. Consider:

- Interest Rate Environment: Higher rates reduce buyer budgets and achievable prices - Help to Buy Availability: Affects first-time buyer demand for 1-2 beds - Local Employment: Major employer changes impact demand - Supply Pipeline: What else is coming to market during your sales period? - Seasonal Factors: Spring and autumn typically see stronger sales

Using GDV in Your Appraisal

Once you have GDV, work backwards:

1. Deduct sales costs (3-5%) for Net Realisable Value 2. Deduct build costs, professional fees, and contingency 3. Deduct finance costs 4. Deduct target profit (15-25% on cost) 5. Remainder = Maximum land bid (residual land value)

The GDV figure anchors your entire financial model. Take time to get it right.