Cable Calc app icon

Cable Calc: cable size and voltage drop calculator

Enter the load, the length and how the cable is installed. Cable Calc picks the breaker, applies the derating factors, checks the voltage drop and shows the cable cross-section you need in mm², to IEC 60364.

Get Cable Calc on Google PlayiPhone version coming soon.
Cable Calc result screen recommending a 6 mm² copper cable with breaker, capacity and voltage drop

What Cable Calc does

Cable size to IEC 60364-5-52

Current-carrying capacity from Annex B for copper cables from 1.5 to 120 mm², PVC (70 °C) or XLPE/EPR (90 °C), installation methods A1, A2, B1, B2, C and E.

Derating built in

Ambient temperature and grouping correction factors are applied for you, and the breaker is chosen so that Ib ≤ In ≤ Iz.

Voltage drop check

The Annex G method with reactance and power factor: drop in volts and %, voltage at the load, pass or fail against your limit, and the minimum size that meets it.

Ohm's law and power

Enter any two of voltage, current, resistance and power to get the other two. Power to current for single-phase, three-phase and DC.

Every step shown

Intermediate values (Ib, In, Iz, correction factors) are on screen, so you can check the working before you sign off.

Made for site work

Works offline, remembers your last inputs and runs in English, German, French, Spanish, Italian, Polish, Portuguese, Turkish and Dutch.

Screenshots

Recommended cable size with breaker, capacity and voltage drop Voltage drop calculation with pass or fail against the limit Earth-fault check with maximum cable length for B, C and D curve breakers Motor circuit with full-load current and starting voltage drop

Free and Cable Calc Pro

Free

  • Cable size with derating and breaker selection
  • Voltage drop calculator
  • Ohm's law and power

Cable Calc Pro

  • Earth-fault disconnection check for TN systems: maximum cable length for B, C and D curve breakers, fault current with a known Ze
  • Motor circuits: full-load current, starting current and starting voltage drop (DOL, star-delta, soft starter, drive)
  • Projects: save calculations per job or customer
  • PDF calculation reports to send to clients
  • No ads

Yearly subscription or one-time lifetime purchase. Prices are shown in the app in your local currency.

Free online tools

Voltage drop calculator in other languages: Spannungsfall-Rechner · Calcul de chute de tension · Calculadora de caída de tensión · Calcolo caduta di tensione · Kalkulator spadku napięcia · Calculadora de queda de tensão · Gerilim düşümü hesaplama · Spanningsval berekenen

Questions

Which standard does Cable Calc use?

IEC 60364-5-52: Annex B for current-carrying capacity and the Annex G method for voltage drop. It suits countries that use metric cable sizes, including most of Europe, the Middle East, Africa and India. It is not built for the US NEC (AWG).

Can I rely on the result without checking?

No. Cable Calc gives guidance based on IEC 60364. Always verify against the standard, the cable manufacturer's data and your national wiring regulations. The installer remains responsible for the design.

Does it work without internet?

Yes. All tables and calculations are in the app, so it works offline on site.

Is aluminium cable supported?

The capacity tables cover copper conductors from 1.5 to 120 mm².

Privacy and support

Read the privacy policy and Terms & Conditions. Questions or feedback: support@mintwavestudio.com.

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