Clients often receive an estimate, quotation and Bill of Quantities at different points and assume the documents are interchangeable. They are not. Each serves a different level of project definition, and confusing them can make a price look more certain than the underlying design actually is.
What is an estimate?
An estimate is a forecast based on the information available at that point. Early estimates may use area benchmarks, comparable projects, allowances and broad quantities. As drawings and specifications develop, the estimate should become more detailed. The important discipline is to state the basis, exclusions and level of confidence rather than present an early number as a fixed promise.
What is a quotation?
A quotation is a price offered for a stated scope, usually by a contractor, supplier or service provider. A quotation can be detailed or extremely brief. Its usefulness depends on whether it identifies quantities, specifications, taxes, preliminaries, exclusions, validity, lead times and assumptions. A total figure without those details is difficult to compare or administer.
What is a Bill of Quantities?
A BoQ organises work into measurable items with descriptions, units and quantities so rates and amounts can be applied consistently. In an interior fit-out it may cover preliminaries, demolition, partitions, ceilings, floor and wall finishes, joinery, furniture, electrical and data works, mechanical changes and other packages depending on the scope.
A useful BoQ or measured schedule should make it easier to see
- What work is included.
- The unit of measurement for each item.
- The quantity being priced.
- The unit rate and extended amount.
- Provisional or uncertain items.
- Alternatives and value-engineering opportunities.
- Changes between revisions.
Why do quotations for the same project differ?
Differences may come from material quality, quantities, labour assumptions, preliminaries, profit and overhead, programme, access restrictions, taxes, exclusions or simply misunderstandings of the design. Before treating the lowest total as a saving, normalise the quotes so each bidder is being compared against the same commercial basis.
How should a client compare quotations?
- Confirm every bidder priced the same drawing revision and specification.
- Check arithmetic, quantities, units and duplicated or omitted scope.
- Separate firm prices from provisional sums and allowances.
- Confirm VAT and other taxes are treated consistently.
- Review exclusions, working hours, access and programme assumptions.
- Check furniture, AV, ICT, MEP and specialist systems explicitly.
- Clarify warranty, defects and handover obligations.
- Record agreed clarifications before award.
What changes under design-and-build?
In design-and-build, the same organisation may develop the design and construction price. That can improve coordination and speed, but the client should still be able to see the scope, allowances and changes clearly. A design-build price should not become a black box; commercial transparency remains important.
Use each document at the right stage
Use an early estimate to test feasibility, a developed estimate to control design decisions, a BoQ or measured schedule to structure procurement and a final quotation or contract sum to record the agreed commercial commitment. The documents should become more precise as the project becomes more defined.
