Calculator
100% development finance calculator
100% development finance is not one loan, it is a stack: senior debt, a mezzanine top-up and JV equity above them. Enter your scheme and your cash, and see how the stack closes the gap and whether the margin supports it.
True 100% development finance is a structured stack, not a single loan. Send us the scheme and we will tell you within one business day whether the numbers support it.
The equity gap, and how the stack closes it
Every development scheme has the same arithmetic problem. Senior development finance stops at around 65 per cent of cost; the scheme costs 100 per cent of cost to deliver. The difference, after mezzanine has taken the debt as far as it goes, is the equity gap, and it has to be funded in cash before a single brick is laid. The calculator models the standard route to closing it: senior debt to 65 per cent of hard costs at 8.5 per cent per annum, mezzanine taking the combined debt to 90 per cent at 14 per cent, both with typical fees, and joint venture (JV) equity funding whatever remains of total cost, including the rolled interest and fees the debt itself generates. Senior interest is estimated on an assumed average drawn balance of 55 per cent of the facility, reflecting staged drawdown; mezzanine interest accrues on the full balance from day one.
On the default scheme, £2,000,000 GDV with £500,000 land, £850,000 build and a 10 per cent contingency over 15 months, the senior facility is roughly £933,000, the mezzanine top-up around £359,000, and the JV equity needed about £282,000 with no developer cash in. The funding card shows the stack covering 100 per cent of total cost. Enter the cash you actually have and the equity requirement falls pound for pound; set it to zero to model the true 100 per cent structure, covered in full on our 100% development finance page.
What the JV equity costs you
The equity slice has no interest rate, which is why no rate field appears against it. A JV partner funds it in return for a share of the profit: typically a priority return of 8 to 12 per cent per annum on their cash as of June 2026, paid before any split, then a residual profit split negotiated deal by deal. That is the real price of 100 per cent funding, and it is paid out of margin rather than cashflow. To see what a given priority return and split would leave you in pounds, run the equity figure from this page through our JV profit split calculator. How partners invest into a development SPV, and what they expect in governance as well as return, is covered on our development equity page.
When 100% funding is realistic, and when it is not
The gating number is profit on cost: projected profit divided by total project cost. Equity partners generally require 20 per cent or more, a harder test than the 17.5 per cent senior lenders apply, because the partner stands last in the repayment queue and the margin is their entire downside protection. The calculator flags which side of the 20 per cent line your scheme sits on. A scheme at 25 per cent profit on cost with planning granted and a credible contractor can realistically be fully funded in 4 to 8 weeks. A scheme at 15 per cent will not be rescued by structure: the gap funder's return has to come from somewhere, and on a thin scheme there is nowhere for it to come from.
Outputs are illustrative estimates based on fixed rate and leverage assumptions, not a quote, an offer of finance or advice. Actual terms depend on the scheme, your track record and each funder's underwriting at the time.
Frequently asked questions
Is 100% development finance a real product?
Not as a single loan. No mainstream UK development lender advances 100 per cent of cost on a standard facility as of June 2026. What developers call 100% development finance is a structured stack: senior debt to around 65 per cent of cost, mezzanine taking the debt to around 90 per cent, and joint venture (JV) equity funding the remainder. Each layer comes from a different funder with its own pricing and security, and the calculator on this page models exactly that stack.
What is the equity gap on a development scheme?
The equity gap is the difference between total project cost, including rolled interest and fees, and the maximum debt the scheme supports. On the calculator's default scheme, hard costs of £1,435,000 support roughly £1,291,500 of combined senior and mezzanine debt, while total cost including finance comes to about £1,573,000, leaving a gap of around £282,000. That gap is what your own cash or a JV partner must fund before the scheme can start.
What does JV equity cost compared with debt?
JV equity has no interest rate. The partner funds the equity slice in return for a share of the profit, typically after a priority return of 8 to 12 per cent per annum on their cash as of June 2026, with residual profit splits commonly between 50/50 and 35/65 depending on track record and contribution. On a strong scheme that is dearer than mezzanine debt; on a scheme that goes wrong it is far safer, because there is no fixed repayment accruing against you.
When is 100% development finance realistic?
When the margin pays for it. Equity partners generally want profit on cost of 20 per cent or more before they will fund the gap, because their return lives entirely inside that margin and it is also their only downside protection. Below 20 per cent most partners decline rather than negotiate. Planning permission granted, a credible build contract and a developer or contractor with comparable completed schemes are the other gates a fully funded structure must pass.
Do I need any of my own money in a 100% funded scheme?
Not necessarily. Set the cash available field to zero and the calculator models a true 100 per cent structure where the partner funds the whole equity slice. Partners do prefer some developer cash, even 2 to 5 per cent of cost, because it proves alignment; with none, expect a lower share of residual profit and harder scrutiny of your track record and build contract.