Standards-compliant electrical calculators for New Zealand electricians. Cable size, Ohm's law, wire converter, and three-phase power — free, no signup required.
100% free. No account needed. Works on mobile.
All calculations run directly in your browser. No account needed.
Formulas:
V = I × R (Ohm's Law)
P = V × I (Power)
P = I² × R
P = V² / R
Enter in watts
Common Loads:
Dedicated calculators for specific tasks. Each with full SEO-optimised pages and standards compliance.
Check if your electrical panel can handle an EV charger. Panel utilisation, recommended breaker, cable size, and RCD protection.
Calculate how many cables fit in a conduit. Supports TPS, single core, and flexible cables. PVC and steel conduit.
Calculate motor full load current, recommended breaker, cable size, and overload settings. Supports single and three phase.
Size a generator based on your electrical loads. Supports motors with starting surge and demand factor adjustment.
Calculate voltage drop for any cable run. Copper and aluminium, single and three phase, with power factor correction.
Calculate how much an appliance costs to run. Daily, monthly, and annual costs based on wattage and usage.
Calculate your electrical business profitability. Employees, jobs per week, average job value, and overhead.
All calculations run in your browser — results appear as you type with no delay.
Covers AS/NZS 3000 (NZ/AU), BS 7671 (UK), and IEC standards. Switch between regions in one click.
Use on-site from your phone or tablet. No app download needed — runs in any browser.
All calculators are 100% free. No account, no email, no credit card. Just open and calculate.
Get these tools plus job management, invoicing, timesheets, certificates, and payroll — all in one platform built for New Zealand electricians.
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Yes, all calculators on this page are completely free to use. No account or signup is required. Advanced features like saving calculations and exporting to job notes are available with a TPT account.
The cable size calculator supports AS/NZS 3000:2018 for New Zealand and Australia, and BS 7671:2018 for the United Kingdom. You can select your region to get the correct standard applied.
Yes. All calculators are mobile-optimised and work in any smartphone browser. They also work offline once the page has loaded, so you can use them even in areas with no signal.
Enter the design current (amps), cable run length (metres), supply voltage, and maximum allowable voltage drop percentage. The calculator returns the minimum conductor cross-section in mm² that meets AS/NZS 3000 or BS 7671 requirements.