Development finance calculator

How much a lender will advance against a development scheme, and how much of your own money you need behind it. It applies both limits lenders actually use, shows which one is holding you back, and gives the residual land value as a range rather than pretending to a single figure.

Enter the gross development value and the build cost and the figures appear here. Nothing is sent anywhere — the whole calculation runs in your browser.

The three things this gets right

Development debt is two limits, not one

Lenders cap the facility at a percentage of gross development value and at a percentage of total cost, and you get the smaller of the two. Cambridge & Counties publish theirs openly — up to 65% of gross development value and up to 80% of cost. On a scheme with a £2,000,000 value and £1,500,000 of cost, that is £1,300,000 by value against £1,200,000 by cost: the cost limit binds and quoting the loan-to-GDV figure alone would overstate the facility by £100,000.

Which one binds tells you what to change. If cost binds, more equity or lower cost moves the needle. If value binds, the scheme is not worth enough for the debt you want.

Developer’s profit is measured two different ways, and RICS picks neither

The RICS professional standard defines profit on cost and profit on value as separate measures and does not require one over the other. They are not close. On a £2,000,000 scheme with £1,367,000 of non-land costs, 20% profit produces a residual land value of £233,000 measured against value, £299,666 against total cost including the land, and £359,600 against cost excluding it.

That is a spread of £126,600 — more than half the land value — from a choice most calculators make silently on your behalf. This one asks.

The residual is a range, because the method demands it

RICS warns in terms that “small variations in these inputs can cause relatively high variations in the residual output”, and that reliance should not rest on a single method. On the scheme above, flexing value and build cost by just 5% each way moves the land value from £88,650 to £377,350 against a central figure of £233,000 — a spread of more than four times.

Any development calculator that hands you one confident number is misrepresenting how the method behaves. This one shows you the corner where the scheme stops working.

What is deliberately missing

Finance costs. RICS says interest on borrowings should not appear in a formal appraisal, because the discount rate already carries the risk premium — while acknowledging that rolling up finance is widespread practice in residual work. Those are two different models, and adding interest to an appraisal built the first way double-counts the risk. Rather than pick one and hide the choice, this calculator omits finance and tells you it has. Add your own interest estimate to the cost side if you work the other way.

Also missing: staged drawdown, which is what makes development interest genuinely hard to compute, and any allowance for VAT or stamp duty on the land purchase. For the last of those, see the commercial stamp duty calculator.

Where the figures come from

Method: RICS, Valuation of development property, RICS professional standard, global, 1st edition October 2019, effective 1 February 2020 — the residual definition at §6.1.1, the cost heads at §6.1.6, profit on cost and profit on value in the glossary, and the sensitivity warning at §7.1.2. Dual lending limits from Cambridge & Counties Bank’s published product table. All captured 26 August 2026.

This is a calculator, not a valuation and not advice. A residual appraisal is one method among several and RICS is explicit that it should not be relied on alone.