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Construction Calculators for UK Builders

60 building tools — 6 free forever, the lot for £9/month

Construction calculators for real site estimates

Use these calculators to turn measured dimensions into practical material quantities, allowances and first-pass costs. They cover common jobs including concrete, roofing, drainage, paving, timber, paint and job margins, with units and assumptions shown alongside the result.

Treat every result as an estimating aid. Confirm dimensions on site, use the current supplier specification, add an appropriate waste allowance and obtain professional design where the work is structural or safety-critical. Results can then be carried into the Builder Tools quote flow instead of being typed out again.

Done with the calculation?

Put the result straight into a professional quote

Add labour, materials, exclusions and your customer details, then keep the quote with the job instead of losing the numbers in a note.

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Electrical

Cable LookupPro

Preliminary lookup for named Doncaster 70°C multicore copper cables using published current-capacity and voltage-drop data. Final circuit design remains with a competent electrician.

DownlightsPro

Calculate optimal downlight spacing and positioning for any room size.

Voltage DropPro

Calculate voltage drop using an exact public Doncaster table for named 90°C single-core copper cables. No cable selection or compliance claim.

Structural

ConcreteFree

Calculate concrete volumes for slabs, footings, columns, and steps. Get mix ratios and material quantities.

Steel WeightPro

Calculate indicative section weights and create a steel schedule. This is not structural member sizing.

Stair GeometryPro

Create a straight private-stair set-out and compare rise, going, pitch and 2R+G with Approved Document K guidance for England.

ScaffoldingPro

Calculate scaffolding hire costs for independent, birdcage, and tower scaffolds. Erection, hire, and dismantle pricing.

Catnic LintelPro

Check an engineer-supplied total UDL against Catnic's February 2026 TS90/100, TH90/100 and TX90/100 table for one defined cavity-wall build-up.

Timber Span CheckPro

Capture the inputs needed for a current timber span-table check and identify when a project-specific structural design is required. No section size is inferred.

Documents

Profit CheckerFree

Check whether a quote covers materials, labour, overheads, contingency, and your target profit margin before you send it.

Site Management

Profit CheckerFree

Check whether a quote covers materials, labour, overheads, contingency, and your target profit margin before you send it.

Roofing

RoofingPro

Calculate roof area, tiles needed, battens, felt, and ridge tiles for pitched roofs.

U-Value EstimatePro

Estimate an idealised layer-stack U-value and compare it with a selected current Part L limiting value. Not a compliance calculation.

Carpentry

Spindle SpacingPro

Calculate equal spindle and end gaps against a designer-chosen clear-gap maximum. The complete guarding still needs verification.

Stair GeometryPro

Create a straight private-stair set-out and compare rise, going, pitch and 2R+G with Approved Document K guidance for England.

Timber Span CheckPro

Capture the inputs needed for a current timber span-table check and identify when a project-specific structural design is required. No section size is inferred.

Stone Masonry

Spindle SpacingPro

Calculate equal spindle and end gaps against a designer-chosen clear-gap maximum. The complete guarding still needs verification.

StoneSmartPro

Calculate stone volumes and costs with labour and markup. Toggle m³/ft³. Save and load jobs to continue later.

WeightPro

Calculate weights of common construction materials by volume or dimensions.

Bricklaying

Stone, Blocks & BricksPro

Calculate stone, bricks, blocks, and mortar needed for walls. Supports stone walling, standard UK brick and block sizes.

Landscaping

FencingPro

Calculate fence panels, posts, concrete, and gravel boards for any fence run.

PatioPro

Calculate paving slabs, sand, cement, and sub-base materials for patios and landscaping.

DeckingPro

Calculate decking boards, joists, noggins, posts, and fixings needed. Full materials list ready for the merchant.

Turf & LawnPro

Calculate turf rolls, topsoil, and fertiliser needed for any garden. Supports rectangle, L-shape, and circular lawns with waste allowance.

Plastering

Plaster & RenderPro

Calculate plaster and render quantities for walls and ceilings. Multi-coat support.

General Building

Plaster & RenderPro

Calculate plaster and render quantities for walls and ceilings. Multi-coat support.

WeightPro

Calculate weights of common construction materials by volume or dimensions.

U-Value EstimatePro

Estimate an idealised layer-stack U-value and compare it with a selected current Part L limiting value. Not a compliance calculation.

PaintFree

Calculate how much paint you need for any room. Accounts for doors, windows, coats, and tin sizes.

Groundworks

WeightPro

Calculate weights of common construction materials by volume or dimensions.

Drainage FallPro

Check bounded Approved Document H minimum falls using actual internal pipe size, design flow, connected WCs and run length.

Gravel & AggregatePro

Calculate tonnes of gravel, MOT, sand, topsoil, and aggregate needed. Built-in bulk densities, multi-area support, and bulk bag counts.

Tiling

Tile CalculatorPro

Calculate tiles, adhesive, and grout for floors and walls. Supports straight, brick bond, and diagonal layouts with wastage.

Plumbing & Heating

Gastite LookupPro

Conservative lookup of Gastite Table 9.1 for its own CSST carrying natural gas under the published fixed conditions. For competent Gas Safe engineers only.

Radiator / BTUPro

Create a rough early-stage heating-load placeholder. Final emitter selection requires room-by-room heat-loss design and manufacturer output data at the actual system temperatures.