Development Finance Calculator
What this calculator actually does
Most people arrive at a development finance calculator with one question: does the deal work?
This tool answers it in the same order a lender does. It sizes the facility we could offer against your costs and your end value, retains the interest and fees, and shows you the equity you need to put in and the profit you would keep.
Type over any figure. The results update as you go, so you can test a higher land price, a longer sales period, or a keener rate and watch what it does to your bottom line.
It is built as a property development finance calculator for UK schemes, ground-up residential, conversions, and mixed-use, and it uses the real levers we underwrite against, not rounded guesses.
A number on a screen is not a credit decision. It is a starting point for a conversation.
How development finance is calculated
Development finance is not a single loan handed over on day one. It is a facility drawn down in stages as the build progresses, with interest charged only on what you have actually taken.
We size the facility against two ceilings at the same time:
- Loan to cost (LTC): a percentage of your total project cost, including land, build, contingency and fees.
- Loan to GDV (LTGDV): a percentage of the gross development value, the figure your finished scheme is expected to sell for.
The lower of the two wins. That single rule decides more deals than any other.
From that gross loan we retain the rolled-up interest and the arrangement and broker fees. What is left is your net advance, the money that actually funds the build. The gap between your total cost and that net advance is the equity you bring.
Rolled-up interest means you make no monthly payments during the build. Interest accrues and is repaid with the capital at the end. It protects your cash flow, but the longer the facility runs, the more it costs.
A worked example
Take the scheme loaded into the calculator above: a £1.95m site, £7.44m of build, and a £14.92m GDV over a 30-month term. On stretched senior terms, here is how it resolves.
| Stretched senior, 30-month term | Figure |
|---|---|
| Total project cost (excl. finance) | £10.74m |
| Loan to cost ceiling (90%) | £9.67m |
| Loan to GDV ceiling (70%) | £10.44m |
| Gross loan - the lower ceiling wins | £9.67m |
| Rolled-up interest + all fees | £1.79m |
| Net advance to build | £8.03m |
| Day-one equity you bring | £2.72m |
| Profit after finance | £2.39m |
Loan to cost bites first at 90%, which puts loan to GDV at just under 65%, comfortably inside the 70% ceiling. Lifting the GDV cap would release nothing here. That is the kind of thing this calculator makes obvious in a second.
Change the rate, the term, or the land price and the whole picture moves. That is the point of running it.
What drives your development loan interest rate
There is no single development loan interest rate. Your rate is priced to the risk of your specific scheme.
As a rough guide for 2026, senior development finance for experienced developers on well-structured residential schemes has typically been pricing in this range:
- 6.5-7.5% pa - lower leverage, strong track record, prime location
- 8-10% pa - higher leverage or stretched senior facilities
- 12-15% pa - mezzanine, sitting behind the senior debt
These are market ranges, not our quote, and they move with the Bank of England base rate. The levers that move your own rate are consistent:
- Leverage: the more you borrow against cost and GDV, the more the lender is exposed, and the higher the rate.
- Experience: a proven delivery record earns keener pricing. First-time developers usually pay a premium.
- The scheme: type, location, and evidenced sales demand all feed the number.
- The exit: a clear, credible plan to repay, sale or refinance, is worth more than any single input.
The question is not simply what rate you can get. It is what the whole facility costs over the time you hold it.
The true cost of a development facility
The headline rate is only part of the bill. A development finance loan calculator earns its keep by showing you the rest.
- Interest: rolled up and charged on drawn funds, so the timing of your drawdowns matters as much as the rate.
- Arrangement fee: a one-off fee for setting up the facility, usually 1-2% of the gross loan.
- Exit fee: charged on redemption, commonly 1-2% of the gross loan or GDV. Not every lender charges one.
- Valuation and monitoring surveyor fees: for the initial appraisal and the stage sign-offs before each drawdown.
- Legal fees: yours and the lender's, for the loan and security documentation.
Underestimating these is the most common way a developer overpays for a site. If you assume finance will cost £500k and it costs £1m, you have quietly overpaid for the land by £500k.
Model it before you offer, not after you complete.
Development exit: when the build is done but the sales are not
Sometimes the units are finished and the development facility is nearing its end, but the sales haven't all landed.
That is where a development exit bridge comes in, a lower-cost loan that repays the development facility and buys you time to sell without pressure. Because the risk has fallen once the scheme is built, the rate usually falls too.
You can model that scenario with our development bridging finance calculator by shortening the term and lowering the rate to reflect a completed, de-risked asset. Some developers know this tool as a development bridging loan calculator; the principle is the same, you are pricing the cost of holding finished stock while it sells.
Some honesty about timelines
You will see tools that promise a decision in seconds and money in hours. Treat that claim with care.
We can give you indicative terms quickly, often within one working day. But a full development facility is not an overnight product. A professional valuation, a monitoring surveyor's review of your costs and programme, and the legal work take time. Realistically, expect four to eight weeks from application to first drawdown on a typical scheme.
Speed is real. Instant is marketing.
What we look for
Development finance is lent against the strength of the project and your ability to deliver it. The basics apply:
- A viable scheme: the numbers have to leave enough profit to absorb an overrun. If the margin is wafer-thin, no lender will take the risk.
- A real equity contribution: expect to fund roughly 30-40% of total cost on standard senior terms, less if you stretch, more if the deal is harder.
- Planning in place or a clear, evidenced route to it.
- A credible exit: sale, refinance, or both, with comparables to back the GDV.
- A team that can build: your track record, your contractor, and your professional team all matter.
Bad credit does not automatically rule you out. Declare it early. We would far rather understand it up front than find it later.
Frequently asked questions
How is development finance calculated?
A lender sizes the facility against two ceilings at once, a percentage of total cost (loan to cost) and a percentage of finished value (loan to GDV). The lower figure wins. Rolled-up interest and fees are retained from that gross loan, and what is left is the net advance you build with. Interest is charged only on funds as you draw them.
What development loan interest rate should I expect?
In 2026, senior development finance for experienced developers on solid residential schemes has typically priced between roughly 6.5% and 9.5% per annum, with the sharpest rates on lower-leverage deals with a strong track record. Stretched senior and mezzanine sit higher. Your rate reflects leverage, experience, scheme type, location and the strength of your exit.
Is this a formal loan offer?
No. It is an illustration to help you test whether a scheme stacks up. Real terms follow underwriting, a professional valuation, and a monitoring surveyor's review. A figure here is not a credit decision.
Do I pay interest monthly?
Usually not. Interest is almost always rolled up, it accrues through the build and is repaid with the capital at the end of the term. That protects your cash flow while you build, but the longer the facility runs, the more interest you pay.
How much equity do I need?
Your equity is the shortfall between total project cost and the net advance. On standard senior terms that often lands around 30-40% of total cost, though it moves with leverage, scheme and experience. The calculator shows your day-one equity for the figures you enter.
Can I get 100% development finance?
Effectively, only through a joint venture, where a funding partner covers land and build in exchange for a share of profit. A standard facility always expects you to contribute equity. Treat "100%" claims as an invitation to read the profit split.
This development finance calculator is provided for general information and illustration only. It does not constitute a formal quotation, an offer of finance, financial advice, or a commitment to lend, and it should not be relied upon as such. All figures are estimates based on the inputs you provide and simplified assumptions, in particular, interest is modelled on an average drawn balance rather than a full drawdown schedule, so actual costs will differ.