Calculator Inputs
Use electrical values or enter a known connected load. The form uses three columns on large screens, two on medium screens, and one on mobile.
Example Data Table
| Scenario | Phase | Voltage | Current | PF | Demand Factor | Diversity Factor | Load Factor | Design Demand | Monthly Energy |
|---|---|---|---|---|---|---|---|---|---|
| Workshop panel | Three | 400 V | 180 A | 0.92 | 80% | 1.15 | 58% | 87.79 kW | 14,403.56 kWh |
| Small office feeder | Single | 230 V | 95 A | 0.96 | 72% | 1.10 | 51% | 15.28 kW | 2,817.20 kWh |
| Known connected load case | Three | 415 V | — | 0.90 | 78% | 1.20 | 60% | 64.35 kW | 10,429.49 kWh |
Formula Used
Single-phase real power
kW = (V × I × PF) / 1000
Three-phase real power
kW = (√3 × V × I × PF) / 1000
Maximum demand
Maximum Demand (kW) = Connected Load × Demand Factor
Diversified demand
Diversified Demand (kW) = Maximum Demand / Diversity Factor
Design demand with reserve
Design Demand (kW) = Diversified Demand × (1 + Reserve Margin)
Apparent demand
kVA = Design Demand / PF
Average load
Average Load (kW) = Diversified Demand × Load Factor
Energy estimate
Monthly Energy (kWh) = Average Load × Hours per Day × Days per Month
How to Use This Calculator
- Select Electrical values if you know voltage, current, and power factor.
- Select Known connected load if the installed load is already available in kW.
- Choose single phase or three phase operation.
- Enter the voltage and either current or connected load.
- Provide power factor, demand factor, diversity factor, and load factor.
- Add reserve margin for future growth or design allowance.
- Enter operating hours per day and days per month.
- Click Calculate kW Demand to see results above the form.
- Use the graph to compare connected, demanded, diversified, and average loads.
- Export the visible result block with the CSV or PDF buttons.
Frequently Asked Questions
1) What does kW demand mean?
kW demand is the real power a system is expected to require at peak use. It helps size feeders, transformers, switchgear, generators, and service capacity more accurately.
2) Why is demand lower than connected load?
Connected load assumes every device runs together at full rating. Real installations rarely operate that way, so demand factor reduces connected load to a more realistic peak requirement.
3) What is the difference between demand factor and load factor?
Demand factor compares maximum demand to connected load. Load factor compares average load to maximum demand or diversified demand. One estimates peaks, while the other estimates usage consistency.
4) Why does diversity factor reduce total demand?
Different loads peak at different times. Diversity factor accounts for this non-simultaneous behavior, reducing the combined demand that the upstream equipment must actually support.
5) Should I use single-phase or three-phase mode?
Use single-phase for typical small circuits and many residential loads. Use three-phase for industrial motors, larger commercial systems, and most plant distribution networks.
6) Why is power factor included?
Power factor links real power to apparent power. A lower value increases current and kVA demand for the same kW, which affects cable sizing and equipment selection.
7) What does reserve margin do?
Reserve margin adds design allowance above diversified demand. It is useful when future expansion, seasonal growth, or uncertain operating conditions may increase actual demand later.
8) Is monthly energy the same as maximum demand?
No. Maximum demand is an instantaneous peak level in kW. Monthly energy is total consumption over time in kWh, based on average load and operating schedule.