Work it out.
Calculators tailored to electrical work: understand the fundamentals, size the cable, work out power and load, and see the economics. Enter your own values — the result updates live.
Step A — The basis
Start here: Ohm's law and power — the relationship between voltage, resistance, current and power.
Step B — Cable & voltage drop
Size the cable: calculate the voltage drop and find the smallest cross-section that stays within the limit.
Step C — Power & load
Calculate power in single-/three-phase systems and add several circuits together with a diversity factor.
Three-phase power
Active, apparent and reactive power
Group load & simultaneity
Design power and current for multiple groups
Load current IB
Current for a known power — 1-phase, 3-phase or motor
Motor starting current
Inrush factor and peak current at start
Solar panels on the roof
Which way the roof faces point, and how many panels fit
Step D — Protection & verification
Kontrollér sikkerheden: tåler lederen kortslutningen (K²S² ≥ IK²·t), og vælg RCD/HPFI så berøringsspændingen holder i TT-systemet.
Step E — Finances
Convert power and run time into kWh and cost using your own electricity price.
Step F — Lighting design
Dimension lighting systems according to EN 12464-1: find lux on the work surface or number of lamps to reach your target lux.
Step V — Directory
Guided multi-step wizard: from desired power to a specific transformer size and max. voltage drop — pure geometry on your answers plus the R5 number series.
Tools that work in all subjects
Maths and templates that work in every trade — and at school. Every tool shows the formula and the working with your own numbers.
- 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.