Calculators that show
their working.
Cable sizing, volt drop, load current and solar sizing for people who have to sign the drawing. Every result names the formula and the standard it came from, so you can check it before you use it.
Calculators
All 51 calculators →- IS 732 · IS 3961
Cable Sizing Calculator
Size a copper or aluminium cable from load current, run length and installation conditions, with derating and volt drop both checked.
- IS 732 cl. 6.1
Voltage Drop Calculator
Check volt drop across a run in volts and percent against the 3 % lighting and 5 % power limits.
- IEC 60898 · IEC 60947-2 · Ib ≤ In ≤ Iz
MCB & MCCB Sizing Calculator
Pick the breaker rating, trip curve and breaking capacity for a circuit — and check it actually protects the cable rather than just fitting the load.
- IS 732 · IEC 60947-4-1 AC-3
Motor Starter & Protection Sizing
Motor full load current, then the contactor, overload relay, breaker and cable that go around it — snapped to standard ratings.
- IS 1180 · IEC 60076 · IEC 60909
Transformer Sizing & Fault Level
Full load current on both windings, how loaded the transformer really is, and the terminal fault current your switchgear has to break.
- Telescopic slab billing
Electricity Bill & Energy Cost Calculator
Units and rupees for any load, through a slabbed tariff rather than a flat rate — plus the payback on replacing it with something more efficient.
Latest posts
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Why distribution transformers fail: one mechanism, ten routes to it
Almost every failure mode ends as heat or water in the paper. The 6 °C rule that quantifies it, and the oil tests that see it coming months ahead.
PROFIBUS and PROFINET: how each is wired, and what breaks
Purple cable at 150 Ω against green Ethernet, powered termination against none, device addresses against device names — and the fault each design invites.
Types of earthing: plate, pipe, rod and chemical compared
Plate, pipe, rod and chemical earthing all obey one formula. What separates them is soil resistivity, depth and who maintains them — not the electrode material.