Downloadable spreadsheet · Excel + Google Sheets

Design your 12/24/48 V system. Offline, in metric.

Voltage drop, cable & fuse sizing, battery bank, solar and alternator, with a load budget that feeds them all. Metric and AS/NZS-aware. AS/NZS wiring defaults included; adaptable for ABYC (US/CA) builds.

Get it now for A$29.99 (approx. US$18)

One-time A$29.99 (approx. US$18) · Excel + Google Sheets · free v1.x updates · 14-day money-back guarantee, no questions asked

What’s inside

My System: set voltage & chemistry once
Load Budget to total daily Ah
Voltage Drop (metric, AS/NZS target)
Cable & Fuse Sizing (ampacity-aware)
Battery Bank Sizing
Solar Array Sizing
Alternator Output
Cable reference (mm2 to AWG)

Why it beats the free calculators

  • Metric mm² cable, not imperial AWG
  • Sizes cable on voltage drop AND ampacity
  • Recommends fuse/breaker ratings
  • Load budget flows into battery & solar
  • Offline, editable: Excel + Google Sheets

A look inside

Screenshot: Overview tab
Screenshot: A calculation tab
Screenshot: Results

Questions

Does it follow AS/NZS standards?

It uses AS/NZS-informed defaults (e.g. a 5% voltage-drop target) and metric mm² cable sizing, and it is designed for Australian boats. It is a planning aid, not a certification tool — final wiring must be verified by a licensed marine electrician against the current AS/NZS 3000 and 3004.2 standards.

Does it size cable and fuses?

Yes. It sizes cable on both voltage drop and ampacity (taking the larger), recommends a standard mm² size and a fuse/breaker rating, and flags when a fuse would exceed the cable ampacity.

Excel or Google Sheets?

Both — one file works in Excel, Google Sheets, LibreOffice and Numbers, fully offline.

Ready when you are

From the team behind the 50+ free marine calculators at boatcalculators.com.au.

Get it now for A$29.99 (approx. US$18)

14-day money-back guarantee, no questions asked