The property development appraisal calculator.

Know the numbers.
See the potential.

Explore development value, costs, finance and projected profit in one clear appraisal. Built for property developers, investors and finance brokers.

Clear assumptions. Transparent calculations. Professional reports.

The CourtyardFour homes · Residential development
Illustrative example
Estimated GDV£2,400,000
Total development cost£1,920,000
Projected profit£480,000
Profit on cost 25.0%   /   Profit on GDV 20.0%

A clearer path through the numbers

One opportunity.
The whole picture.

From the first assumptions to the final figures, understand what makes a development work.

  1. 01

    Describe the opportunity

    Start with the property, proposed scheme and the project information you have.

  2. 02

    Review the assumptions

    Look at the sales values, costs and finance assumptions behind the appraisal.

  3. 03

    Understand the outcome

    Explore projected profit and what a change in the figures could mean.

Explore this journey through a fictional sample. Live appraisals are not available on this website.

An appraisal, opened up

From opportunity
to a clearer decision.

A headline figure is only the beginning. Explore the costs, allowances and assumptions that sit beneath it.

Our page-by-page sample explains what each part of an appraisal tells you, and where further investigation is needed.

Inside the appraisal Six sample pages. Every number in context.
TBN Stack illustrative appraisal for The Courtyard: £2.4 million GDV, £1.92 million costs and £480,000 projected profitIllustrative example 01 / 06 ↗

Clarity, not just a total

The assumptions
behind every number.

A useful appraisal makes it clear what is known, what has been calculated and what still needs checking.

Explore the assumptions page ↗
01Project information
The scheme and information supplied by the person preparing the appraisal.
02Supporting evidence
Sources and dates where available. Our fictional sample makes no claims about real properties or comparable sales.
03Calculated results
Figures that follow from the stated inputs, with clear definitions for profit on cost and profit on GDV.
04Open assumptions
Estimates, allowances and unresolved questions that could change the result.

A few useful answers

Before you
look closer.

What is GDV?

Gross Development Value is the estimated combined sales value of a development when complete. It is a sales estimate, not the projected profit.

Who is TBN Stack for?

Property developers, investors and development finance brokers who want a clearer understanding of a proposed scheme and its financial assumptions.

What information do I need?

Start with the property and proposed scheme. A useful appraisal also needs estimated sales values, land and acquisition costs, construction costs, other allowances and finance assumptions. Unconfirmed information should remain clearly labelled.

Can I change the assumptions?

The sample on this website is a fixed illustration. Reviewing and revising assumptions belongs in the private application, which is not connected to this website yet.

What does the appraisal include?

This six-page example covers the opportunity, sales assumptions, development costs, a simplified finance allowance, sensitivity and outstanding checks. It illustrates the information an appraisal can bring together; it does not reproduce the full appraisal engine.

Does this replace a professional valuation?

No. Results depend on the inputs and assumptions. They are not a formal valuation, a lending decision or a guarantee of profitability. Obtain appropriate professional advice before committing to a project.

TBN Stack

See how your next
development stacks up.

Explore the appraisal

A fictional scheme. A practical introduction.