Electrical load calculator for a home: connected load to amps
This electrical load calculator turns a list of appliances into the numbers an electrician or utility asks for: connected load in kW, maximum demand after a demand (diversity) factor, kVA, the current in amps on a single- or three-phase supply, the next standard MCB size and the sanctioned load to apply for.
Three methods are built in because the rules differ by country. India mode multiplies the connected load by a demand factor, on 230 V single-phase or 415 V three-phase. US mode follows the NEC Article 220 standard method for a dwelling and sizes the service. UK mode applies the IET On-Site Guide (BS 7671) diversity allowances and compares the result with the cut-out fuse.
It is a planning estimate, not a design: a licensed electrician must check it, and the sanctioned load, phase and protective devices are decided by your electricity supplier and the electrician.
How to use the Electrical Load Calculator
- Pick the method: India (demand factor), US (NEC 220) or UK (BS 7671 diversity).
- India: add appliances from the preset list or type your own with watts and quantity; set the demand factor, power factor and supply type.
- US: enter the floor area, circuit counts, fastened appliances, range, dryer, heating and air-conditioning ratings.
- UK: enter lighting, heating, cooker, socket circuits, showers, immersion heater, EV charger and the service fuse.
- Read the maximum demand, kVA, amps and the suggested MCB, service or fuse check, then copy the summary for your electrician.
Electrical Load Calculator features
Appliance list with presets
Fans, lights, fridge, AC by tonnage, geyser, pump, EV charger and more, with editable wattages.
Demand factor and power factor
Maximum demand = connected load × demand factor; kVA = kW ÷ power factor; I = P ÷ (V × pf) or P ÷ (√3 × V × pf) for three-phase.
NEC 220 standard method
220.41 lighting load, 220.52 circuits, Table 220.45 tiers, 220.53 appliances, Table 220.55 ranges, 220.54 dryers, 220.60 non-coincident loads and 220.50 motors.
UK diversity (IET On-Site Guide)
Lighting at 66%, cooker 10 A + 30% + 5 A, sockets 100% + 40%, showers, immersion and EV at 100%, checked against a 60, 80 or 100 A fuse.
MCB and sanctioned-load suggestions
The next standard MCB above the design current, the load to request and a three-phase flag above your threshold.
Worked example: a typical Indian home
Four fans (300 W), ten LED lights (100 W), a TV, fridge, 1.5-ton AC (1,800 W), geyser (2,000 W), washing machine, microwave, 1 HP pump and 500 W of other sockets add up to a connected load of 7.45 kW. Not everything runs together, so a demand factor of 0.6 gives a maximum demand of 4.47 kW. At a power factor of 0.8 that is 5.59 kVA and, on 230 V single-phase, I = 4,470 ÷ (230 × 0.8) = 24.3 A, so the next standard MCB is 25 A (many electricians go one size up for headroom) and you would apply for a 5 kW sanctioned load. If the demand crosses the DISCOM’s single-phase limit, a three-phase connection is required, where the same 7.45 kW draws only 13 A per phase. The limit is set by each state: Delhi’s DERC schedule allows single-phase up to 10 kW, while many supply codes switch at 5 kW (checked October 2026), so the threshold is an input.
NEC 220 standard method, step by step
| Step | Rule (NFPA 70-2023) | 2,000 ft² example |
|---|---|---|
| General lighting | 3 VA per ft² of floor area (220.41) | 6,000 VA |
| Small-appliance + laundry | 1,500 VA per circuit, at least two + one (220.52) | 4,500 VA |
| Demand factor | First 3,000 VA at 100%, 3,001–120,000 at 35%, rest 25% (Table 220.45) | 5,625 VA |
| Fastened appliances | 75% of the total when four or more (220.53) | 8,100 × 0.75 = 6,075 VA |
| Range, dryer | 8 kW for one range ≤ 12 kW (Table 220.55); 5,000 W or nameplate for a dryer (220.54) | 8,000 + 5,000 VA |
| Heating vs cooling | Larger of the two only (220.60) | 10,000 VA |
| Total ÷ 240 V | Next standard service, minimum 100 A (230.79) | 34,700 VA → 145 A → 150 A |
kW to amps and what the numbers mean
- kW to amps: single-phase I = P ÷ (V × pf); three-phase I = P ÷ (√3 × VL × pf). 1 kW at 230 V and 0.8 pf is 5.4 A; at 415 V three-phase it is 1.7 A per phase. The watt calculator does the plain conversion without diversity.
- Connected load is the sum of nameplate ratings; maximum demand is what actually flows at the busiest moment; sanctioned load is the contract figure on your bill. Exceeding it can mean penalties or a forced upgrade.
- Demand factor is an engineering assumption, not a code constant: 0.5–0.7 suits most homes; use 1.0 if everything can run at once.
- Cable size follows the protective device: see the wire gauge calculator, and the electricity bill calculator for running costs.
Electrical Load Calculator FAQ
How do I calculate the electrical load of my house?
Add up every appliance’s wattage × quantity for the connected load, multiply by a demand factor (about 0.6) for the maximum demand, divide by voltage × power factor for amps, then take the next standard MCB size. The electrical load calculator shows each step.
What sanctioned load should I apply for?
Round the maximum demand up to the next kilowatt — 4.47 kW becomes 5 kW — and discuss it with your DISCOM: they decide the sanctioned load, and single-phase supplies are commonly limited to 5–10 kW depending on the state.
How do I convert kW to amps for a home?
Amps = watts ÷ (volts × power factor). 4,470 W at 230 V and 0.8 pf is 24.3 A single-phase; on 415 V three-phase divide by √3 × 415 × 0.8 to get 7.8 A per phase for the same load.
Which NEC method does the US mode use?
The standard method of Article 220 Part III (NFPA 70-2023), including Table 220.45 lighting demand factors, 220.53 appliances, Table 220.55 ranges, 220.54 dryers and 220.60 non-coincident loads. The optional method in 220.82 is not included.
Where do the UK diversity percentages come from?
From the individual-household column of the diversity table in the IET On-Site Guide to BS 7671 (Table 1B in older editions). EV chargers are not in that table and are treated as continuous loads at 100%.
Can I size the main breaker from this?
Use it to anticipate the size, the next standard rating above the design current. A licensed electrician must check the calculation and select the final MCB, cable and earth fault protection.