Ten free calculators for UK site teams, grouped by job: groundworks, concrete and steel, planning and cost, and roofing and access. See what each one does, which to use for which task, and how they work together on a typical job.
Site teams make the same calculations again and again: how much concrete, how many skips, what fall on a drain, how long a task will really take. Doing them by hand or in a half-forgotten spreadsheet invites mistakes, and mistakes on site cost money.
KaelSite offers ten free calculators built for UK construction work. They are free to use and need no registration. This guide explains what each one does, groups them by job, and shows how to use several together. Each calculator has its own full guide with formulas, worked examples and UK points to know, linked below.
You can also browse them all on the KaelSite tools page.
Excavation and Spoil Removal Calculator
Turns a dig volume into loose spoil using soil bulking, then counts skip or tipper loads, journeys and disposal cost. Essential because 20 m³ in the ground is more than 20 m³ on the tip. Read the guide: Excavation and Spoil Removal Calculator.
Pipe Gradient and Fall Calculator
Converts a 1:N gradient into total fall, ending invert level and fall per metre, or works backwards from two invert levels. It also flags an adverse gradient. Read the guide: Pipe Gradient and Fall Calculator.
Aggregate and MOT Type 1 Calculator
Converts length, width and compacted depth into volume and tonnes of MOT Type 1 or other aggregate, with compaction and wastage allowances. Read the guide: Aggregate and MOT Type 1 Calculator.
Concrete Volume Calculator
Works out m³ for slabs, strip and pad foundations, trenches, footings and circular columns, adds wastage and rounds up truck loads. Read the guide: Concrete Volume Calculator.
Rebar Weight Calculator
Converts bar diameter and length into kilograms and tonnes, or weighs mesh sheets such as A393, with wastage and cost. Read the guide: Rebar Weight Calculator.
Material Cutting Optimiser
Plans cuts from standard lengths of steel, timber, pipe or conduit to use fewer stock lengths and produce a cutting list, allowing for kerf and reusable offcuts. Read the guide: Material Cutting Optimiser.
Construction Cost and Labour Calculator
Calculates total labour hours, labour cost, cost per unit and productivity per worker for bricklaying, excavation, concrete and general labour. Read the guide: Construction Cost and Labour Calculator.
Working Days and Construction Programme Calculator
Finds a finish date from a start date and number of working days, or counts working days between two dates, allowing for week patterns, bank holidays and shutdowns. Read the guide: Working Days and Construction Programme Calculator.
Roof Pitch Calculator
Converts rise and run (or span) into pitch angle, ratio, slope percentage and common rafter length, with a simple slope area for a gable. Read the guide: Roof Pitch Calculator.
Scaffold Load Calculator
An educational tool that shows how platform area and a uniform load combine into a total imposed load. It is not a scaffold design tool and does not replace TG20 or a competent person. Read the guide: Scaffold Load Calculator.
Most jobs need more than one calculation. Here are three common combinations.
A strip foundation
A driveway or hardstanding
A drainage run
Planning any of them
Use the Construction Cost and Labour Calculator for crew hours and cost, then the Working Days and Construction Programme Calculator to turn the days into a finish date.
These calculators are for planning, ordering and learning. They do not replace the design by the responsible designer, the Building Regulations, British Standards, manufacturer data or professional advice. The scaffold calculator in particular is educational only and is not a scaffold design tool.
Are the calculators really free?
Yes. They are free to use and need no registration.
Can I use them on my phone on site?
Yes. KaelSite is built mobile-first, and the tools work in a mobile browser.
Do the calculators include VAT, labour or delivery in cost estimates?
Not unless you build them into the rates you enter. Cost figures are estimates only.
Can the calculators replace a designer or engineer?
No. They help with planning and ordering. Structural, drainage, scaffold and temporary works design must come from competent people.
Which calculator should I start with?
Pick the one closest to the task in front of you, then follow the combinations above for the rest of the job.
Do the tools work for materials other than steel and concrete?
Several do. The cutting optimiser works for timber, pipe, conduit and aluminium, and the aggregate calculator covers scalpings, crushed concrete and ballast as well as MOT Type 1.
Calculators help with the numbers. Running a site also means inspections, safety records, photos and reports. KaelSite is a mobile-first construction app for UK site management, inspections, safety and reporting, designed to support CDM 2015, with offline capabilities and AI-powered training and report drafting. Explore KaelSite features.
References
KaelSite
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