Cable size calculator — India 2026

Six application modes with mode-specific drop budgets and ampacity safety factors. Pick the mode → set the NBC building grade → enter current (or HP) and run length. Output is sized against both IS 8130:2013 conductor resistance and IS 3961:2024 ampacity tables, then mapped to the right BIS-licensed flame grade for your occupancy.

How this works

Voltage drop uses the standard formula Vdrop = k × I × R × L, where k = 2 for single-phase (round-trip) or DC, and k = √3 for three-phase (line-to-line). Resistance values come from IS 8130:2013 Table 1 (Class 2 stranded copper, max DC resistance at 20 °C, scaled to 70 °C operating temperature using the standard's temperature coefficient).

Each application mode applies its own ampacity safety factor before checking the size against IS 3961:2024 free-air, 30 °C ambient ratings: 1.00× for home wiring, 1.25× for motor and pump (per IEC 60364-5-52), 1.10× for panel feeders and IEC industrial. The drop budget is also mode-specific — 2 % on panel feeders (sub-DB headroom), 3 % on home / motor / pump branches, 4 % on shop-floor IEC, and 1 % on solar PV strings to preserve array yield.

The NBC building-grade dropdown selects the right flame grade and IS standard for the occupancy: FR (IS 694:2010) for residential up to G+3, FR-LSH (NBC §4.14) for G+4 and above and commercial, HFFR (IS 17048:2018, HCl < 0.5%) for hospitals / metro / airports, IS 1554 PVC armoured or IS 7098 XLPE for industrial LT/HT power, and IEC 62930 / IS 16527 for solar DC strings.

For production sizing, also apply grouping factors, ambient-temperature derating above 30 °C, and buried / conduit / trefoil installation factors per the standard's tables. Always verify the final cable schedule with a qualified electrical engineer.

Output is indicative. Verify against project specification, NEC / IEC tables, and the manufacturer's datasheet. CablePriceIndia accepts no liability for installation outcomes.