Quick answer (updated October 2026): A building estimator prices construction work, usually for a contractor or client before work starts. A quantity surveyor (QS) does that too, but also manages costs across the whole project — cost plans, bills of quantities, tendering, valuations, variations and the final account. For a single price from drawings, either can help; for cost control through the build, you need a QS.
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What Does a Building Estimator Do?
An estimator works out what a building project will cost to build. They take the drawings and specification, measure the quantities of work and materials, and apply rates for labour, materials, plant and overheads to reach a price.
Estimators are most often employed by contractors and subcontractors to price tenders, but clients also use them to check that a quote is reasonable. The output is usually an estimate: a priced breakdown of the work, organised by element or trade.
What Does a Quantity Surveyor Do?
A quantity surveyor manages construction costs across the life of a project. Estimating is part of the job, but a QS also prepares cost plans as the design develops, produces bills of quantities in NRM2 format, runs tenders, and once work starts looks after interim valuations, variations, cost reports and the final account.
A QS can work for the client (sometimes called the “professional QS”) or for the contractor (the “commercial QS”). Either way, the role is to make sure the project is priced fairly, paid for fairly and finishes on a budget everyone has agreed.
The Key Differences
| Estimator | Quantity Surveyor | |
|---|---|---|
| Main focus | Pricing work before it starts | Managing cost from design to final account |
| Typical output | Estimate or tender price | Cost plan, BoQ, valuations, final account |
| Usually works for | Contractors and subcontractors | Clients or contractors |
| Involvement | Before the contract | Before, during and after the contract |
In practice the roles overlap a great deal. Many quantity surveyors work as estimators, and many experienced estimators do QS work. What matters more than the job title is the person’s qualifications and experience with your type of project.
Qualifications to Look For
Quantity surveyors usually hold a degree in quantity surveying or construction, and many are members of a professional body such as the Chartered Institute of Building (CIOB) or the Royal Institution of Chartered Surveyors (RICS). Estimators may come through a trade or construction management route.
Our team are qualified Quantity Surveyors with over 50 years’ combined experience. Our Managing Director, Stephen Jones, holds ICIOB, BSc and HDip qualifications, and every estimate we produce is prepared and checked by a qualified QS. You can meet the team here, and our guide to choosing a building estimator covers what to ask before you appoint anyone.
Where the Roles Overlap in Practice
On a typical extension or small development, the first piece of cost work is the same whoever does it: measure the drawings, apply current rates and produce a priced breakdown. That is estimating, and a qualified QS does it as a core part of the job. The difference shows up later. Once a contract is signed, an estimator’s work is usually done, whereas a QS carries on — valuing work for interim payments, pricing changes as they happen and keeping the budget under control until the final account is agreed.
Contractors see the same overlap from the other side. A builder’s estimator prices the tender; the commercial QS then manages that price through the job. Smaller firms often combine the two roles in one person, or outsource both. Many of our builder clients use us as their estimating department, sending tender packs for us to price so they can focus on running sites.
Questions to Ask Before You Appoint Anyone
- What qualifications and professional memberships does the person preparing my estimate hold?
- Will the estimate be checked by a second qualified person?
- What will I receive — an itemised breakdown, or a single figure?
- Is the price fixed before work starts?
- How are regional differences in labour and material costs allowed for?
- What support is available after the estimate is delivered?
For us, the answers are simple: qualified Quantity Surveyors, every estimate prepared and checked by a qualified QS, an itemised PDF and editable Excel file, a fixed-price quotation upfront, regional rates, and ongoing support to explain line items and compare quotes.
Which One Do You Need?
If you need a price for a project from your drawings — to set a budget, support a planning or funding application, or check a builder’s quote — an estimate is what you need. Our budget, planning drawing and building regulation estimates start from £75 + VAT.
If you are running a larger project and want costs controlled from design through to completion, appoint a QS for cost planning and post-contract services. Contractors bidding for work can use our tender pricing service, from £250 + VAT.
Not sure? Tell us about your project and we’ll recommend the right service, with a fixed-price quotation and no obligation.