CableCalc 18-4 Professional Electrical Design Software
Fast, accurate electrical design software for cable sizing, distribution board calculations and BS 7671 compliance.
Updated for BS 7671 Amendment 4
Designed for electricians, contractors, consultants and engineers, CableCalc simplifies electrical design with fast, accurate cable sizing, voltage drop, earth fault loop impedance and protective device calculations to BS 7671.
Generate professional calculation reports, distribution board schedules and schematic diagrams in minutes, saving time while improving accuracy and consistency across every electrical design project.
Updated for BS 7671:2018+A4:2026
PVC, XLPE, LSF, MICC, SWA, Flex, Fire Resistant and Aluminium cables
Available for both desktop platforms
From Single Cable Calculations to Complete Distribution Board Design
CableCalc combines powerful electrical design tools with an intuitive workflow, helping professionals produce accurate, compliant electrical cable calculations, distribution board designs and project documentation to BS 7671 quickly and efficiently.
Whether you're sizing a single final circuit or designing a complete electrical installation, CableCalc provides the calculations, reports and schematic diagrams needed to streamline design work and reduce the risk of costly errors.
Choose from four licence levels to match your requirements, from everyday cable sizing through to advanced multi-distribution board projects with manufacturer protective devices, schematic diagrams and comprehensive design schedules.
Create branded reports, export PDF documentation, customise design settings and produce professional project documentation ready to issue to clients, consultants and approval bodies.
BS 7671 Amendment 4
Updated for BS 7671:2018+A4:2026 including changes affecting buried cable calculations.
Four Licence Levels
Choose the edition that matches your projects, from single circuits to unlimited distribution boards.
Professional Documentation
Create branded calculation reports, schedules, schematic diagrams and PDF documentation in minutes.
Windows & macOS
One licence, one familiar workflow, available on both Windows and Mac desktop platforms.
CableCalc 18-4 - Level 1
Fast Circuit Design
Ideal for single circuits, ring final circuits and everyday cable calculations.
Level 1 gives electricians and engineers the essential tools for quick, accurate cable sizing, voltage drop, earth fault loop impedance and protective device checks to BS 7671.
- Radial and ring final circuits
- Single-phase and three-phase calculations
- Copper cable database
- Generic protective devices
- Detailed calculation documents
Supply
Set supply details and circuit type.
Cable
Choose cable type, size and installation method.
Correction
Apply grouping, ambient temperature and installation factors.
Protection
Select the protective device and rating.
Results
Review checks, reports and PDF output.
Ideal for quick everyday calculations
Level 1 is perfect for single circuits, ring final circuits and straightforward cable calculations where speed, clarity and reliable BS 7671 checks matter most.
Level 1 is perfect for electricians and engineers who need fast, reliable cable calculations.
View Purchase OptionsCableCalc 18-4 - Level 2
Installation Design
Design complete electrical installations with up to five distribution boards.
Design complete installations
Wide range of circuit types
Export branded PDF reports
Building on Level 1, CableCalc Level 2 introduces project-based design, allowing installations to be organised, calculated and documented within a single professional project file.
Level 2 supports multiple distribution boards, sub-main calculations, lighting circuits and motor circuits while generating professional documentation ready for clients and approval bodies.
Project Design
Organise complete installations with up to five distribution boards, circuits and schedules.
Motor Circuits
DOL and Star Delta motor calculations with integrated design checks.
Sub-main Calculations
Voltage drop, Zs and protection checks between distribution boards.
Lighting Circuits
Domestic, commercial and street lighting calculations, including looped circuits.
Professional Documentation
Circuit details, schedules, discrimination graphs and single-line diagrams.
Level 1
- Single circuit calculations
- Simple 5-step workflow
- Ring and radial circuits
Level 2
- Complete project design
- Up to 5 distribution boards
- Motor circuits
- Sub-main calculations
- Lighting circuits
- Professional documentation
Our most popular choice for electrical contractors. Start with a free first month on monthly plans and experience complete project design with CableCalc Level 2.
Compare Licence OptionsCableCalc 18-4 - Level 3
Professional Engineering
Advanced electrical design with manufacturer-specific protective devices.
Level 3 includes all Level 1 and Level 2 features, supports projects with up to 20 distribution boards, and introduces manufacturer-specific protective devices for more detailed project design.
- Distribution board schematic drawings
- Single-line project layout diagrams
- User-defined protective devices
- Up to 20 distribution board schedules
- Manufacturer-specific protective devices
- New Schneider Electric catalogue including ACBs, MCCBs, MCBs and RCBOs
- Legacy catalogue for Square D, MEM, Wylex, Hager, Crabtree and more
protective device catalogue for 2026
Distribution Board Design
Create detailed board schedules, diagrams and schematic drawings.
Manufacturer Protection
Select from manufacturer-specific devices, including the new Schneider Electric catalogue.
Up to 20 Distribution Boards
Manage larger projects with multiple boards and detailed schedules.
Professional Reports
Generate calculation reports, schedules and diagrams ready to issue.
Level 3 is ideal for contractors and engineers who need advanced design capabilities and manufacturer-specific protective device selection.
Special Offer — Save £200. Now £495 normally £695CableCalc 18-4 - Level 4
Design Without Limits
Unlimited distribution boards and complete project flexibility.
CableCalc BS7671 18-4 Level 4 is the ultimate design tool for electrical consultants and advanced designers. Create high-quality, compliant cable designs for projects of any size, with no restriction on the number of distribution boards.
DBs
Unlimited distribution boards
Design without restrictions. Add as many distribution boards as your project requires.
Complete project visibility
Generate detailed distribution board diagrams, schedules and schematic drawings.
Aluminium cables database
Access the aluminium cables database for accurate, time-saving design.
Accurate, compliant and reliable.
Includes Level 1, 2 and 3 features, plus manufacturer-specific protective devices.
WITH DESIGN LICENCE PACKAGE
No charge during the first 30 days.
Cancel online anytime.
All Level 4 features included.
CableCalc Level Comparison Chart
Choose the CableCalc level that best matches the size and complexity of your electrical design projects.
| Features | Level 1Essentials | Level 2Professional | Level 3Advanced | Level 4Complete |
|---|---|---|---|---|
| Detailed calculation printout | ||||
| Add company logo to printouts | ||||
| Export printout as PDF | ||||
| Adiabatic CPC size calculations | ||||
| Single-phase calculations | ||||
| Device time/current graphs | ||||
| PVC twin and earth cables | ||||
| Ring circuit calculations | ||||
| Radial circuit calculations | ||||
| Three-phase calculations | ||||
| PVC, XLPE and LSF cables | ||||
| FP fire resistant cables | ||||
| Flex and tri-rated cables | ||||
| MICC, rubber and more | ||||
| Lighting circuit calculations | ||||
| Sub-main circuit calculations | ||||
| Star delta motor calculations | ||||
| DOL motor calculations | ||||
| Project design up to 5 DBs | ||||
| Circuit details printout | ||||
| Design schedule printouts | ||||
| Device discrimination graphs | ||||
| Single-line diagrams | ||||
| Manufacturer protective devices | ||||
| Up to 20 distribution boards | ||||
| User-defined protective devices | ||||
| DB schematic diagrams | ||||
| Distribution board diagrams | ||||
| Aluminium cables | ||||
| Unlimited distribution boards |
CableCalc BS7671
Professional Electrical Calculations on the go
Portable electrical calculation software for on-site cable sizing, voltage drop checks and BS 7671 circuit verification.
Calculate & check
Voltage drop, disconnection time, fault current, earth fault loop impedance and protective device data.
Single & three-phase
Carry out calculations for radial, ring and sub-main circuits directly on site.
Save & export
Save calculations and produce detailed PDF reports for printing or emailing.
Cable types included
- 70°C PVC Armoured & non-armoured multi-core & singles, twin & earth, 6491x & 6181y Singles
- 90°C LSF Armoured singles & multi-core, 6491b & 6181 Singles, Twin & earth, Flat 3 core & earth
- 90°C XLPE Armoured & Non Armoured singles & Multi-core, 6491b & 6181xy singles
- FP100, FP200, FP200 Flex, FP400 and Fireforce PH30 Fire rated
- MICC PVC Sheath/Bare, Heavy & Light Duty
- CY, SY, YY 70°C PVC Flexible cable, 105°C Tri-Rated singles
- 60 & 90°C Rubber insulated flexible cable
Trusted electrical design software
CableCalc BS7671 18-4 helps electrical contractors, consultants, engineers and designers carry out cable sizing, voltage drop checks, fault current analysis, distribution board schedules and schematic diagrams for BS 7671 electrical installation projects.
Get CableCalc 18-4 in one of two ways:
1. Subscription Licence – from £16.50/month: Start with a free first month on monthly licence plans. There is no charge during your first 30 days, and you can cancel online anytime before renewal.
Annual licences offer the best value, saving 20% compared with paying monthly, making them the most popular choice for regular users.
2. Standalone Purchase – one-off payment: Buy CableCalc outright with 12 months of upgrades, maintenance, and support included.
- Save £200 for a limited time only
All prices are exclusive of VAT
Purchases of CableCalc 18-4 come with access to both Mac and Windows versions. Compatible with Windows 7, 10, 11 and MacOS 11 (Big Sur) or later. Additional user licences are required for use on more than one computer.
CableCalc for iOS mobile devices
- CableCalc BS7671 for iPad - £129.99
- CableCalc Lite for iPhone/iPad - £FREE