A builder’s estimate is an informed indication of what the work may cost. A builder’s quote—or quotation—is normally an offer to carry out defined work for an agreed price, subject to its stated terms and any permitted adjustments.

The practical difference is cost certainty.

An estimate can change as the design, quantities or site conditions become clearer. A quotation should provide a firmer price for an identified scope, although it can still change if you request extra work, allowances are adjusted or the contract provides another valid basis.

Do not rely only on the heading at the top of the document. Read how the price, scope and possible changes are actually described.

Estimate Versus Quote: The Short Answer

Estimate	Quote or quotation
An indication of likely cost	An offer to undertake defined work for an agreed price
May be based on incomplete information	Should be based on a sufficiently identified scope
Expected to change as information develops	Intended to remain fixed for the agreed scope, subject to its terms
Useful for early budgeting	More suitable for contractor appointment
Should explain its assumptions and uncertainty	Should explain inclusions, exclusions, allowances and permitted adjustments

The words quote and quotation generally mean the same thing. Different builders use different document titles, so the wording and commercial effect matter more than whether the heading says “quote”, “quotation”, “proposal” or “estimate”.

What Is a Builder’s Estimate?

An estimate is the builder’s assessment of what the work is likely to cost based on the information available at the time.

It may be appropriate where:

The design is at an early stage
Structural information is incomplete
Product specifications have not been chosen
Quantities cannot yet be measured reliably
Existing conditions have not been investigated
Specialist subcontractor prices are unavailable
The homeowner needs an initial feasibility budget

An estimate may be presented as:

A single approximate figure
A cost range
A price per square metre
A schedule of estimated work sections
A budget based on stated assumptions

A useful estimate should explain the information used, the level of design development, major assumptions, exclusions, VAT treatment and how long the pricing basis is expected to remain relevant.

The word “estimate” should not be treated as permission for an unlimited or unexplained increase. It means the price has less certainty, not that the homeowner has agreed to pay any amount later demanded.

What Is a Builder’s Quote?

A quote is normally an offer to complete identified work for an agreed price.

It should state clearly:

Who is offering to carry out the work
Which property and project it covers
Which drawings and specifications were priced
The work and materials included
Important exclusions
PC sums, provisional sums and other allowances
Whether VAT is included
The total price
How long the offer remains valid
Circumstances in which the price may change
Payment and other commercial terms

Citizens Advice describes a quote as a fixed price and recommends obtaining it in writing. Business Companion similarly explains that a quotation is normally a fixed price, while an estimate is generally a rough indication of cost.

In building work, “fixed” must still be read against the agreed scope and contract. A fixed quotation for a defined extension does not automatically include later design changes, additional work or the final value of clearly identified adjustable allowances.

Is a Quotation the Same as a Fixed Price?

Usually, a quotation is intended to provide a fixed price for the work it defines. However, the complete document may contain both fixed and adjustable elements.

For example:

Price component	Amount	Cost status
Defined construction work	£88,000	Fixed for the stated scope
PC sum for tiles	£4,000	Adjustable when tiles are selected
Provisional sum for drainage	£6,000	Adjustable when work is defined
Quotation total excluding VAT	£98,000	Includes £10,000 of allowances

The document can still be a quotation, but not every pound within the total carries the same certainty.

Before accepting it, separate fixed work from allowances and understand how each adjustable amount will be calculated.

Is a Budget Price the Same as an Estimate?

A budget price is usually an early indication used to test affordability or guide design decisions. It often operates like an estimate, but there is no universal meaning.

A budget price might be based on:

Floor area
Previous similar projects
Broad work sections
An early drawing package
Assumed specification levels
Current rates with a general risk allowance

Ask the builder to state whether the budget is:

A broad feasibility figure
An estimated range
A detailed estimate
Intended to become a quotation after further information

Do not appoint a builder or set the final project budget using an early budget figure without confirming what remains unpriced.

Why the Document Title Is Not Enough

A document headed Quotation might still contain wording that makes the total highly adjustable. An Estimate might contain certain sections that have been firmly priced.

Look for phrases such as:

Estimate only
Budget estimate
Guide price
Subject to survey
Subject to remeasurement
Subject to final design
Prices to be confirmed
Rates subject to change
Materials charged at cost
Labour charged by the day
Final price after opening up
Excludes unforeseen work
Fixed price for the stated scope
Valid for 30 days

Read these statements together with the scope, exclusions, allowances and proposed contract.

If the document’s heading and its detailed wording conflict, ask the builder to clarify the intended price basis and issue a revised document.

When Is an Estimate Appropriate?

An estimate can be useful during project development.

It may help you:

Decide whether a project is broadly affordable
Compare design options
Set an initial funding target
Identify major cost drivers
Decide which specifications need further work
Establish whether professional design should continue

An early estimate should not be forced into false precision. If the builder has only planning drawings and a brief conversation, a tightly stated figure may look reassuring without being dependable.

The estimate becomes more useful when its uncertainty is visible. A range of £140,000–£165,000 with clear assumptions may be more honest than an unsupported figure of £147,250.

When Should You Ask for a Quotation?

Before appointing a builder for substantial work, you should normally seek a written quotation based on sufficiently developed information.

This may require:

Coordinated architectural drawings
Structural design information
A clear schedule of work
Product and finish specifications
Kitchen and bathroom layouts
Electrical and heating requirements
Window and door schedules
Relevant surveys
Clear client-supply responsibilities

Not every uncertainty can be eliminated, particularly in an older building. Remaining uncertainties should be identified through exclusions, provisional sums, PC sums or clearly stated assumptions rather than hidden within vague wording.

A quotation should provide a sound basis for comparing builders and forming the written contract.

What Should an Estimate Include?

Even though an estimate is not a fixed quotation, it should still be understandable.

Look for:

The builder’s correct business details
Project address and description
Date of the estimate
Documents and information reviewed
Scope assumed
Specification level assumed
Estimated amount or range
VAT position
Major exclusions
Important risks and unknowns
Relevant price date
Next information needed
Proposed route to a firmer quotation

If the estimate is a range, ask what separates the lower and upper figures. The answer might relate to specification, structural solutions, ground conditions, access or the extent of existing-property work.

What Should a Quote Include?

A builder’s quote should normally provide greater detail and certainty.

It should establish:

The correct contracting party
The project documents priced
Detailed inclusions
Relevant products and specifications
Work expected from the homeowner or others
Exclusions
Fixed-price sections
Allowances and provisional sums
VAT treatment
Total amount payable
Programme assumptions
Deposit and payment schedule
Variation procedure
Price-validity period
Insurance, certification and handover responsibilities
Proposed contract terms

The detail should be proportionate to the project. A short quote may be adequate for a simple repair; a major extension or renovation needs a much stronger description of scope, responsibilities and commercial terms.

Can a Builder Charge More Than a Quote?

A builder should not simply disregard an agreed quotation because the work became less profitable than expected.

However, the amount payable may legitimately change where:

You request extra or different work
The design or specification changes
A PC sum or provisional sum is adjusted
Previously excluded work is later instructed
Concealed conditions require additional work and you agree how it will be dealt with
The contract contains another applicable price-adjustment mechanism

Citizens Advice explains that a trader cannot charge more than the quoted price merely at will; additional work should be raised and agreed.

For every proposed change, ask for:

A written description
The added or reduced price
VAT treatment
The effect on the programme
Your written approval before the work proceeds, wherever practicable

If you dispute an increase, obtain project-specific consumer or legal advice rather than relying on a general online explanation.

Can a Builder Charge More Than an Estimate?

An estimate can increase because it is not normally a fixed price. That does not mean every increase is automatically reasonable or agreed.

The position depends on:

The estimate’s wording
The assumptions and information supplied
What was later agreed
Whether the scope changed
Whether the builder warned you about increasing costs
The contract terms
The work actually carried out

Where a contract does not determine the price, section 51 of the Consumer Rights Act 2015 provides for a reasonable price to be paid for the service. What is reasonable depends on the particular facts.

If an estimated cost begins to rise, ask the builder to stop and explain the revised forecast before committing further expenditure. Record any agreement in writing.

Worked Example: Estimate Becoming a Quotation

A homeowner is planning a rear extension.

At planning stage, a builder provides this estimate:

Early estimate	Amount
Anticipated construction cost excluding VAT	£110,000–£130,000

The estimate assumes standard glazing, no abnormal ground conditions and a mid-range kitchen installation. Structural engineering, detailed electrical layouts and final finishes are unresolved.

After the design is completed, the builder issues a quotation:

Final quotation position	Amount
Defined construction work	£118,000
Provisional sum for drainage	£5,000
PC sum for floor finishes	£4,000
Quotation excluding VAT	£127,000
VAT at 20%	£25,400
Quotation including VAT	£152,400

The £127,000 quotation sits within the earlier estimated range before VAT, but £9,000 remains adjustable through the drainage and flooring allowances.

The example shows why the homeowner must compare:

Like-for-like VAT positions
The information available at each stage
Fixed prices and allowances
Construction price and total project budget

The estimate was useful for feasibility. The later quotation provides the stronger basis for appointment.

Worked Example: A Quote That Is Not Entirely Fixed

A quotation states:

Extension works — £95,000 plus VAT

Further down, it says:

Electrical work charged at cost
Kitchen installation to be confirmed
Groundworks subject to site conditions
Decoration excluded
Structural steel subject to final engineer’s design

The £95,000 is labelled as a quotation, but substantial cost remains uncertain.

Before accepting it, the homeowner should ask the builder to:

Define the electrical scope or provide an allowance
Price the kitchen installation
State the groundworks assumption
Confirm the steelwork included
Add decoration to the wider project budget
Explain how changes will be authorised and valued

The label “quotation” does not remove uncertainty created by the detailed wording.

Estimate Versus Quote When Comparing Builders

Do not rank an estimate and a quotation together as though they are equivalent offers.

Suppose:

Builder	Document	Submitted total
Builder A	Estimate based on planning drawings	£105,000
Builder B	Detailed quotation based on construction drawings	£122,000

Builder A appears £17,000 cheaper, but the documents do not price the project on the same basis.

Builder A’s figure may change when structural details, specifications and subcontractor prices are confirmed. Builder B may have included work and risk that Builder A has not yet assessed.

Before comparing the totals:

Issue the same information to both builders.
Ask each to confirm whether the document is an estimate or quotation.
Identify missing and excluded work.
Separate fixed prices from allowances.
Put VAT on the same basis.
Ask for revised quotations based on the same information.

The cheapest submitted number is not necessarily the cheapest completed project.

Does Accepting a Quote Create a Contract?

It can.

A contract does not always require a formal signature. Acceptance may occur through written or verbal agreement, paying a deposit, fixing a start date or allowing work to begin.

Business Companion explains that agreeing to a quote can constitute acceptance of an offer. Citizens Advice also warns that you may have formed a contract even where nothing was formally signed.

Before accepting a substantial quotation:

Confirm the final scope and price
Resolve material questions
Check the builder’s legal identity and insurance
Agree the programme and payments
Review cancellation information where applicable
Use a suitable written building contract
Keep the complete agreed document set

A quotation can become part of the contract, but it is not necessarily the only contract document.

Questions to Ask the Builder

Ask the builder to answer these questions in writing:

Is this document an estimate or a quotation?
Is the total fixed for the stated scope?
Which drawings, revisions and specifications have been priced?
Which assumptions support the figure?
What work and materials are included?
What is excluded?
Does the total include VAT?
Which amounts are PC sums, provisional sums or estimates?
What could legitimately change the price?
How will variations be priced and approved?
How long is the price valid?
What further information is required?
When can a final quotation be issued?
What payment schedule is proposed?
Which written contract will apply?

Where the answers change the commercial position, request a revised document rather than relying on a chain of separate messages.

Warning Signs

Clarify the price basis before proceeding if:

The builder cannot say whether the figure is an estimate or quote
A quotation is described as “approximate” throughout
An estimate is presented as a guaranteed final price
No drawings or specifications are referenced
Important work is marked “to be confirmed”
VAT is not addressed
The document contains numerous low allowances
Materials will be charged at cost without explaining mark-ups
Labour will be charged by the day without estimated duration or rates
The builder can increase the price without a clear reason or approval process
The document explains increases but not reductions
Verbal assurances conflict with the written terms
You are pressured to pay a deposit before questions are resolved

No single phrase proves that the builder is unsuitable. It indicates where the scope, price or contract needs clarification.

Frequently Asked Questions

Is a quote legally binding in the UK?

Accepting a quotation can create a binding contract, depending on what was offered, accepted and agreed. Contracts can also be formed verbally or through conduct. Use a suitable written contract for substantial building work and obtain legal advice on specific disputes.

Is an estimate legally binding?

An estimate is not normally a promise that the final price will match the estimated figure. However, agreements made around the estimate can still form a contract, and the builder cannot assume that any eventual charge will be acceptable. The wording, scope, communications and applicable consumer law all matter.

Can a quote change after I accept it?

It can change where extra work, a design alteration, an allowance adjustment or another valid contractual change is agreed. The builder should not increase an agreed fixed price merely because the work costs more than expected.

How much can an estimate increase?

There is no universal permitted percentage. The issue is whether the final price and any increases are reasonable and consistent with what was agreed. Ask for an updated forecast as soon as costs begin to move.

Is a quotation the same as an invoice?

No. A quotation is issued before the work to offer a price and terms. An invoice requests payment for work, goods or an agreed payment stage.

Should I accept an estimate for a house extension?

An estimate may be suitable for early feasibility. Before appointing a builder, seek a detailed written quotation based on sufficiently developed drawings, specifications and structural information, with remaining uncertainty clearly identified.

Is a fixed estimate a quote?

Citizens Advice notes that a quote may sometimes be called a fixed estimate. Labels vary, so ask whether the price is fixed for a defined scope and in which circumstances it can change.

Do builders have to provide quotes for free?

No universal rule requires every builder to prepare a detailed quotation without charge. Ask before commissioning it whether a fee applies, what you will receive and whether the fee is credited if the builder is appointed.

Before You Accept the Price

Confirm that you understand:

Whether the document is an estimate or quotation
Which information was used
What is included and excluded
Whether VAT is included
Which parts are fixed
Which amounts can change
How adjustments and variations will be calculated
How long the price remains valid
What further design or investigation is required
Whether the likely completed-project cost is affordable
When acceptance would create a commitment
Which written contract will record the agreement

An estimate is useful when uncertainty is unavoidable and visible. A quotation is useful when it defines the work and provides a firmer appointment price.

Neither document should be judged by its title alone.

Need Help Understanding a Builder’s Price?

Before You Build provides independent builder quotation reviews for homeowners before a contractor is appointed.

We assess whether the document provides a dependable basis for proceeding, including its scope, specifications, exclusions, allowances, VAT treatment, inconsistencies and potential cost exposure.

First Check — £59: an initial review of one builder’s quotation
Full Check — £119: a more detailed assessment of one quotation
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Before You Build complements the work of architects, quantity surveyors, project managers, engineers, surveyors, legal advisers and other professionals. It does not form or interpret contracts for you, select or recommend a contractor, verify workmanship, provide legal advice or replace project-specific professional services.

This guide provides general information for UK homeowners. It is not legal advice or a definitive interpretation of any particular document or agreement. Whether a price is binding and when it may change depend on the wording, scope, communications, contract and circumstances. Obtain appropriate consumer or legal advice for a specific dispute or contractual decision.

Estimate vs Quote: What’s the Difference?