Professional Electrical Calculatorsfor UK Electricians
Free BS 7671 compliant calculators — cable sizing, voltage drop, load, Zs & more. No signup required.
22
Free Calculators
BS 7671 Compliant
Free, No Signup
Mobile Friendly
Featured Calculators
Professional BS 7671 calculators used by thousands of UK electricians. All tools are free with no signup required.
Cable Size Calculator
Calculate correct cable sizes for BS 7671 compliance
Voltage Drop Calculator
Check voltage drop meets BS 7671 limits for any circuit
Load Calculator
Calculate electrical loads with UK diversity factors
Max Zs Calculator
Verify earth fault loop impedance for protective devices
PFC Calculator
Calculate prospective fault current at any point
Earthing & Bonding
Size earthing and bonding conductors to BS 7671
Ring Final Circuit
Verify ring final circuit continuity test results
Diversity Calculator
Apply diversity factors for maximum demand calculations
Browse by Category
Find the right calculator for your project. Tools organised by use case.
BS 7671 Compliance
Zs, PFC, earthing & circuit protection calculators
Cable & Wiring
Cable sizing, voltage drop & conduit fill tools
Testing & Verification
Ring final, Zs verification & test result tools
Design & Planning
Load, diversity, EV charger & solar sizing tools
Why Electricians Use These Tools
Built for working electricians who need fast, accurate calculations on-site.
BS 7671:2018+A2:2022
All calculators comply with the latest 18th Edition wiring regulations including Amendment 2
Free, No Signup Required
Every calculator is completely free. No account, no email, no hidden paywalls
Mobile-Friendly for On-Site
Every tool works perfectly on your phone. Do calculations on-site, on the job
Shows Working for Certs
Get full calculation breakdowns you can reference in your electrical certificates
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Find the right calculator for your project
22 free BS 7671 calculators for cable sizing, voltage drop, load calculations and more.