Work it out.
Calculators
Earth volume
Grid method (bilinear surface)
Sewer fall
EBAI booklet on drainage plans (2009) based on DS 432
Fall away from the house
Danish Safety Technology Authority / SBi: 1:40, with hard paving 1:50, 3 m out
Stabilised gravel and bedding layer
Geometri + rumvægt
Fall on paving
Procent/promille
Concrete – mix quantities
Ratio arithmetic
Rebar – weight per metre
Massefylde for stål (DS/EN 10080)
Sewer pipe fall – minimum fall for drain pipe
DS 432 (Norm for afløbsinstallationer)
Soil bulking during excavation
Opsvulmningsfaktorer (EngineeringToolbox / ProjectEngineer.net)
Slope batter for excavation
AT-vejledning om bygge- og anlægsarbejde (VEJ nr. 10135 af 01/10/2026), kap. 5 om gravearbejde
Frost-free foundation depth
Bygningsreglementet BR18 §342
Jointing sand for paving
Geometri + producentdata (Dansand)
Number of paving stones per m²
Geometry
Kerb foundation – concrete quantity
Vejregler – AAB Brolægning (Vejdirektoratet, VD 2017-0005)
Ramp – gradient for step-free access
BR18 – adgangsforhold (bygningsreglementet §§ 48-62)
Soakaway – sizing rainwater infiltration
Tommelfingerregel (Bolius' faskine-guide)
Pad foundation – concrete quantity
Geometry
Concrete mixer – number of batches
Producentdata (jem & fix, 125 L betonblander)
Rafter template
Exact flat pattern
Tools that work in all subjects
Whatever your programme is called, these tools calculate the same — Pythagoras, area, percentages and units are not tied to one trade.
- Pythagorasa² + b² = c²Find the missing side, set out a right angle, check whether a room is square, and find the space diagonal.
- Area and perimeterm²Rectangle, triangle, trapezium, circle and composite shapes — area and perimeter.
- Volume and surface aream³ · lBox, cylinder, cone, sphere, pyramid, prism, pipe and frustum — also in litres.
- Percent%Percentage of, how many per cent, percentage change, discount and VAT.
- Scale and ratios1 : 50From drawing to reality, area and volume to scale, the rule of three and dividing in a ratio.
- Unit convertermm ↔ mFrom mm to km, Pa to bar and kB to GB — with the unit staircase.
- Time calculations and the clockt : minTime between two clock times, add time, and 1.75 h = 1 h 45 min for the timesheet.
- Slope and fall% · ° · 1:xFall from level to level, in per cent, per mille, degrees and mm per metre — and the height difference.
- Material consumption including wastem² + %Boards, paint, battens at c/c spacing and packs — for a composite surface or a whole room, with waste.