Highest and best use is the reasonably probable and legal use of a property that is physically possible, financially feasible and results in the highest value. Appraisal Institute guidance applies it twice: to the site as if vacant and to the property as improved. Below we walk through the four tests, the market evidence and a workable assessment sequence.
TL;DR:
- Screen candidate uses in order for legal permission, physical possibility, financial feasibility, and highest return; record why rejected options fail before costly modeling.
- Analyze the site both as vacant and as improved, because demolition and conversion costs can leave the existing building more valuable than redevelopment.
- Before financial modeling, test market support through vacancy, absorption, comparable rents and sales, competing projects, and the share of demand a new project can capture.
- A redevelopment conclusion favors a residual or development approach, while a stabilized income property favors income valuation; match comparable sales to use and timing.
- Commission a full feasibility report or specialist market study when the numbers are tight, zoning may change, or lenders will rely on the conclusion.
Table of Contents
- What are the four tests of highest and best use?
- How do you test a site as vacant and as improved?
- How does market analysis support or eliminate a use?
- What does an eight-step assessment look like?
- How does highest and best use shape a valuation?
- What do the tests look like on real sites?
- Why recording your assumptions matters
- Where we can help with your highest and best use analysis
- FAQ
- Sources
What are the four tests of highest and best use?
Each test acts as a filter, and a use must pass all of them before it is compared with the others. Work through them in order, because a use that fails an early test never needs costly modelling.
- Legally permissible: check zoning, overlays, covenants, easements, permitted uses and how likely a planning change is.
- Physically possible: assess lot size and shape, access, topography, soil, flooding and the availability of utilities and services.
- Financially feasible: model the cost of delivering each remaining use, the developer's required profit and how sensitive revenue is to price and timing.
- Maximally productive: among the feasible uses, choose the one with the highest residual land value or the best return on the property as improved.
IRWA guidance describes this as a funnel: uses that fail a screen drop out, and the survivors are compared on residual returns. The International Valuation Standards frame the same idea, requiring a use that is physically possible, legally allowed and financially feasible.
Pro Tip: Record the reason each rejected use failed. A reviewer trusts a conclusion more when the eliminated options are visible.
How do you test a site as vacant and as improved?
The two premises answer different questions. The site-as-vacant test asks what would be built if the land were empty. The site-as-improved test asks whether the existing building should stay, be altered or be replaced.
- Site as vacant: assess the ideal development of the land, ignoring the current structures.
- Site as improved: compare the value of continuing the existing use with the value of the vacant site less demolition and conversion costs.
- Interim uses: a building may remain the best use for now even when a different use will win once the market matures.
- Documentation: state your assumptions about timing, costs and market conditions, since the existing use stays the highest and best use whenever the improvement still contributes more than the cleared land would.
Demolition cost often settles the question. When clearing a sound building eats most of the land's uplift, keeping it usually wins.
How does market analysis support or eliminate a use?
A use can pass the legal, physical and financial screens and still fail because the market will not absorb it. Start by defining the market area, then collect demand indicators: vacancy, absorption, comparable sales and rents.
- Demand: measure how much space or housing the area is taking up and at what pace.
- Supply: count pending projects and approved but unbuilt developments that will compete with yours.
- Capture: estimate the share of residual demand a new project could realistically win.
- Pricing movement: falling rents, rising vacancy or flat prices can eliminate a use that looked feasible on paper.
Appraisal Institute training materials describe residual demand and capture estimates, along with tiered marketability analyses for complex work. The expanded method in the Appraisal Institute definition puts market delineation and demand analysis ahead of the feasibility modelling.
What does an eight-step assessment look like?
A condensed sequence keeps the opinion defensible and repeatable.
- Gather legal and physical constraints and site data: title, zoning, overlays, survey, services.
- Identify candidate uses that the site could plausibly support.
- Research demand for each candidate in the defined market area.
- Assess competing supply, including pending projects.
- Model capture and absorption for the surviving uses.
- Screen out uses the market will not support.
- Run the cost and financing tests: construction, holding, finance and required profit.
- Conclude on timing and select the highest and best use.
The deliverable is a written opinion listing the data used, the uses rejected and why, the assumptions behind the chosen use and the timing.
Pro Tip: Attach the inputs for every step to the opinion. A conclusion with no visible data trail is hard to defend.
How does highest and best use shape a valuation?
Market value assumes the property is put to its highest and best use, so the conclusion drives the whole valuation. The International Valuation Standards require inputs that match the chosen basis and premise of value.
- Approach selection: a site best used for redevelopment points towards a residual or development approach, while a stabilised income asset points towards an income approach.
- Comparable selection: the conclusion narrows the pool to sales of similar use, similar timing and similar buyer profile. Our guide to comparable sales analysis covers how that selection works with official records.
- Cost and return inputs: conversion costs, income expectations and developer returns decide which approach dominates.
- Practitioner examples: IRWA practitioner guidance works through cases showing the analysis feeding comparable choice and the final conclusion.
What do the tests look like on real sites?
These sketches are illustrative, not market data.
- Small residential parcel: a single dwelling and a duplex are both legal and buildable. The duplex wins only if its profit margin, after extra construction and holding costs, beats the single dwelling.
- Commercial-zoned parcel beside a highway: zoning permits retail, traffic counts support it and nearby vacancy is low, so retail passes every test and becomes the likely use.
- Improved building with high demolition cost: clearing the site would release little extra land value once demolition is deducted, so continuing the existing use remains the highest and best use.
Why recording your assumptions matters
An opinion is only as strong as the assumptions it exposes. Write down the timing, the cost allowances and the capture rate behind your conclusion, so a reader can change one input and see the result move. A desk screen is fine for early triage, but commission a full feasibility report or a specialist market study when the numbers are tight, the zoning may change or lenders will rely on the result. Our piece on commissioning a property feasibility report explains what to expect.
— Ashton
Where we can help with your highest and best use analysis
We build the legal, physical and financial tests into reports. Our services:
- Quick Scan: a fast zoning and constraints check of an address, ideal for early screening.
- Automated Report: a full feasibility analysis with multiple scenarios.
- Founder-Reviewed Report: the same analysis with human review of the conclusions.
- Development Concierge: an inspection, strategy session and introductions to professionals.
Pick the Quick Scan to screen a site, and a reviewed report when money is committed. Start at Sitescope and tell us which site you are weighing up.
FAQ
What is the highest and best use concept?
It is the appraisal principle that a property's value is judged on its most profitable lawful use. That use must be physically possible, financially feasible and reasonably probable. The Appraisal Institute definition applies it to both vacant land and improved property.
How do you calculate highest and best use?
There is no single formula. You screen candidate uses against the legal, physical and financial tests, then compare the survivors by residual land value or return. The use that produces the highest value, given market support and timing, is the conclusion.
What does the phrase "highest and best use" refer to?
It refers to the use of land or buildings that supports the highest present market value. IRWA guidance describes it as the reasonable and probable use, reached by eliminating infeasible options.
Does the highest and best use ever stay as the current use?
Yes. When demolition or conversion costs outweigh the land value uplift, the existing improvement remains the highest and best use. The appraiser documents why the alternatives were rejected.