Cost Per Square Foot Calculator UK: Estimate Your Project Instantly
Whether you're planning a home extension, laying new carpet, or budgeting a commercial fit‑out, our cost per square foot calculator helps you quickly break down pricing. This free tool and guide cover average costs for building, flooring, roofing, and renovations, with practical formulas and expert advice to keep your project on track.
Quick Answer
How do you calculate cost per square foot?
Simply divide the total project cost by the total area in square feet. For example, a £12,000 extension covering 200 sq ft works out to £60 per sq ft.
Use the interactive calculator below to try it yourself – or enter a known per‑square‑foot rate to find the total cost.
Enter any two values to calculate the third. Use this tool for any project – building, flooring, carpet, or painting – and instantly see the result.
The calculator works out the missing value. Leave exactly one field empty.
Average Costs Per Square Foot for Common UK Projects
While the UK primarily uses square metres, many contractors still quote per square foot for certain trades. The table below provides estimated market averages (including labour and materials, excluding VAT) for popular home improvement and building projects.
Project Type
Average Cost Per Sq Ft
Typical Range
Notes
New build (standard spec)
£100 – £160
£90 – £190
Excludes land cost
Home extension (single storey)
£120 – £200
£100 – £250
Depends on foundation & roof type
Loft conversion (basic)
£110 – £170
£100 – £210
Including dormer
Bathroom renovation
£150 – £280
£130 – £350
Fixtures & tiling included
Kitchen renovation
£180 – £300
£160 – £400
Mid‑range units & worktops
Carpet supply & fitting
£8 – £20
£5 – £30
Underlay & fitting included
Engineered wood flooring
£15 – £35
£12 – £45
Floating or glued
Roof replacement (felt)
£25 – £45
£20 – £55
Pitched roof, incl. battens
External rendering
£15 – £25
£12 – £30
Through‑coloured render
Office fit‑out (commercial)
£45 – £90
£35 – £120
Partitioning, electrics, finishes
Estimates based on UK contractor quotations and industry averages. Actual costs vary by location, specification, and site conditions.
How to Calculate Cost Per Square Foot – Formula & Practical Examples
The calculation is straightforward, but many people forget to account for waste or awkward shapes. Here is the formula and a step‑by‑step example.
Basic Formula:
Cost Per Square Foot = Total Project Cost ÷ Total Area (sq ft)
Worked Example – Home Extension
Area: 280 sq ft (rear extension)
Total quoted cost: £42,000 (labour, materials, fittings)
Calculation: £42,000 ÷ 280 = £150 per sq ft
You can also reverse the formula: if a builder quotes £130 per sq ft for a 350 sq ft loft conversion, the estimated total would be £130 × 350 = £45,500.
Key Factors That Influence Per Square Foot Costs
Property location: London and the South East command 20–30% higher rates than the North or Wales.
Specification level: Luxury finishes, underfloor heating, or bespoke joinery push the cost up significantly.
Site access: Difficult access, parking restrictions, or inner‑city logistics increase labour time.
Structural work: Steel beams, underpinning, or roof alterations add cost beyond standard square foot rates.
Trade type: Specialist works (stone flooring, mosaic tiling) carry higher per‑square‑foot charges than general labour.
Project size: Very small jobs often attract a minimum charge, making the effective per‑sq‑ft rate higher.
Regional Pricing Differences (UK)
Because square foot pricing often follows the same regional patterns as square metre rates, the table below shows approximate multipliers compared to the UK average.
Region
Cost Variation vs UK Average
Typical Building Cost (per sq ft)
London
+20% to +30%
£160 – £250
South East
+10% to +15%
£130 – £210
Midlands
On average
£100 – £180
North England
-10% to -15%
£85 – £155
Scotland
-5% to -10%
£90 – £165
Wales
-10% to -15%
£80 – £150
Northern Ireland
-10% to -20%
£75 – £140
Real‑World Cost Examples
Project
Area (sq ft)
Cost Per Sq Ft
Total Estimated Cost
Small carpet replacement (bedroom)
120
£12
£1,440
Medium kitchen extension
200
£160
£32,000
Large office fit‑out
1,500
£65
£97,500
Figures are illustrative market averages and exclude VAT. Always obtain written quotations.
Common Mistakes When Using Square Foot Pricing
Forgetting to confirm units: A quote in square feet can look 10.76 times smaller than the same number in square metres. Always clarify.
Ignoring waste and cuts: Add at least 5–10% extra for material wastage, especially for tiles, carpet, or flooring.
Comparing quotes without checking inclusions: One quote may include skip hire and waste removal, another may not.
Assuming VAT is included: Many small contractors are not VAT‑registered, but larger firms must add 20%.
Using the wrong area: Measure internal floor area accurately – don't rely on estate agent brochures.
Hiring Tips & Checklist
Obtain at least three itemised quotations
Ask whether the rate is per square foot or square metre
Confirm what's included: labour, materials, waste removal, and any preparatory work
Check public liability insurance and relevant trade accreditations
Request a written schedule of works with a timeline
Clarify VAT status before signing
Agree payment stages – never pay 100% upfront
Sources & Methodology
The pricing estimates in this article are compiled from:
UK contractor quotations across multiple regions
Supplier and merchant price lists (carpet, flooring, building materials)
Industry construction cost databases and trade publications
Market research on regional labour rates
How We Estimated These Prices
Our team analysed hundreds of recent project quotes and adjusted them to a per‑square‑foot basis where needed. All figures represent estimated market averages and should be used as guidance only. No proprietary or confidential data has been used.
Written by: Bhumi Calculator Editorial TeamLast Updated: 30 June 2026
Disclaimer: This website provides general information and estimated market averages. It does not constitute professional or legal advice. Always verify costs with qualified local contractors and obtain written quotations before proceeding with any work.
Frequently Asked Questions
How does a cost per square foot calculator work?+
A cost per square foot calculator divides the total project cost by the total area in square feet. You simply enter the area and the overall cost, and the tool instantly gives you the price per square foot. It can also reverse the calculation: enter the per‑square‑foot rate and area to get an estimated total cost.
What is a typical building cost per square foot in the UK?+
Average building costs in the UK range from around £100 to £250 per square foot, depending on the specification, location, and complexity. Basic new builds may fall at the lower end, while high‑end renovations and extensions in London can exceed £300 per square foot.
Can I use this calculator for carpet and flooring projects?+
Absolutely. The calculator is ideal for carpet, vinyl, hardwood, and tile flooring estimates. Simply input the room area (in square feet) and the quoted cost, and the tool will show the cost per square foot, making it easy to compare different suppliers and materials.
Are these square foot costs including VAT and labour?+
Costs shown in our reference tables are estimated market averages that typically include labour and materials, but VAT is not always included. Many sole traders are not VAT‑registered. You should always confirm with the contractor whether VAT is included in the quoted price before starting the work.
How do I calculate the cost per square foot for a renovation?+
To calculate renovation costs per square foot, measure the total floor area of the rooms being renovated, then divide the contractor's quoted price by that area. For example, a £15,000 kitchen extension of 200 sq ft gives a cost of £75 per square foot. Use our calculator above for quick and accurate results.
Why are some costs quoted per square foot instead of per square metre in the UK?+
Although the UK officially uses metric, many trades—especially carpet fitters, flooring specialists, and some builders—still price work per square foot. This is often due to legacy measurement habits and the ease of dividing by smaller numbers. Always check which unit is being used in a quotation.
Is this calculator suitable for commercial projects?+
Yes, the calculator works for both residential and commercial projects. Commercial fit‑outs, office refurbishments, and retail renovations often use square foot pricing. Our commercial average costs table provides a helpful benchmark for office spaces, shops, and industrial units.