MON - FRI 8AM - 5PM
(86) 159 6789 0123
Professional tools for sizing generators and calculating power requirements
Choosing the correct generator size is essential for reliable power supply. Our generator size calculator helps you determine the exact capacity needed based on your appliances and equipment. Simply input your devices' running and starting watts to get an accurate recommendation.
Understanding the difference between running watts and starting watts is crucial. Running watts represent the continuous power consumption during normal operation, while starting watts (also called surge watts) are the temporary power spike needed when motors, compressors, and pumps first start up. This surge can be 2-5 times higher than running watts.
Our calculator automatically adds a 25% safety margin to ensure your generator can handle unexpected loads and operates efficiently without being overworked. This extends the generator's lifespan and ensures stable power delivery.
| Appliance | Running Watts | Starting Watts | Notes |
|---|---|---|---|
| Refrigerator | 700W | 2,200W | Compressor motor requires high starting power |
| Air Conditioner (10,000 BTU) | 1,500W | 4,500W | Large compressor motor |
| Electric Water Heater | 4,000W | 4,000W | Resistive load, no surge |
| Microwave Oven | 1,000W | 1,000W | Electronic load, minimal surge |
| Washing Machine | 1,200W | 3,600W | Motor-driven, high starting current |
| LED TV (50") | 150W | 150W | Electronic device, no surge |
| Electric Kettle | 1,500W | 1,500W | Resistive heating element |
| Desktop Computer | 300W | 300W | Electronic equipment |
Running Watts: The continuous power an appliance uses during normal operation.
Starting Watts: The temporary surge power needed to start motors, compressors, and pumps. This can be 2-5 times higher than running watts.
Total Running Load: 0 kW (0 W)
Total Starting Load: 0 kW (0 W)
Recommended Generator Size: 0 kW / 0 kVA
Safety Margin Applied: 25% (recommended for reliable operation)
Add appliances above and click calculate to see detailed breakdown.
Three-phase power is more efficient for large loads and industrial applications. Our phase conversion calculator helps you determine the current requirements and generator specifications when converting between single-phase and three-phase systems.
Three-phase systems distribute power across three conductors, resulting in lower current per phase compared to single-phase for the same power output. This means smaller wire sizes, reduced losses, and more efficient operation for motors and heavy equipment.
Use this calculator to compare single-phase and three-phase requirements for your load, helping you make informed decisions about generator selection and electrical system design.
| Feature | Single Phase | Three Phase |
|---|---|---|
| Typical Voltage | 120V, 240V | 208V, 240V, 415V, 480V |
| Current Formula | I = P / (V × PF) | I = P / (√3 × V × PF) |
| Power Delivery | Pulsating | Constant, smoother |
| Efficiency | Standard | Higher (up to 150% more efficient) |
| Best For | Residential, light commercial | Industrial, heavy equipment |
| Wire Size | Larger for same power | Smaller, more economical |
Current: 0 A
kVA: 0 kVA
Voltage: 0 V
Current per phase: 0 A
kVA: 0 kVA
Line voltage: 0 V
Recommendation: Enter values above and calculate to see recommendation.
Understanding power measurements is crucial when selecting and sizing generators. Our power conversion tools help you convert between kVA (kilovolt-amperes), kW (kilowatts), watts, and amps - the most common units in electrical systems.
kVA represents apparent power, while kW represents real power. The relationship between them depends on the power factor, which varies based on the type of load. Resistive loads (heaters, lights) have a power factor near 1.0, while inductive loads (motors, transformers) typically range from 0.7 to 0.9.
| Conversion | Formula | Example |
|---|---|---|
| kVA to kW | kW = kVA × Power Factor | 100 kVA × 0.8 = 80 kW |
| kW to kVA | kVA = kW ÷ Power Factor | 80 kW ÷ 0.8 = 100 kVA |
| Watts to Amps (Single Phase) | Amps = Watts ÷ Voltage | 2400W ÷ 240V = 10A |
| Amps to Watts (Single Phase) | Watts = Amps × Voltage | 10A × 240V = 2400W |
| HP to kW | kW = HP × 0.746 | 10 HP × 0.746 = 7.46 kW |
| kW to HP | HP = kW ÷ 0.746 | 7.46 kW ÷ 0.746 = 10 HP |
Enter kVA or kW value above and click convert to see results.
Formula: kW = kVA × Power Factor | kVA = kW ÷ Power Factor
Enter Watts or Amps value above and click convert to see results.
Formula: Watts = Amps × Volts | Amps = Watts ÷ Volts
Fuel consumption is a critical factor in generator operating costs. Our fuel consumption calculator provides accurate estimates based on generator size, load percentage, and fuel type. Understanding fuel consumption helps you plan for runtime, budget for fuel costs, and ensure adequate fuel storage.
Fuel consumption varies significantly with load. Generators operating at 75-80% of rated capacity achieve optimal fuel efficiency. Running at very light loads (under 30%) or maximum capacity both increase fuel consumption per kW produced.
Different fuel types have varying consumption rates and energy densities. Diesel generators are typically the most fuel-efficient, followed by natural gas, LPG, and gasoline. Factor in fuel availability, storage requirements, and local fuel costs when selecting a generator.
| Fuel Type | Consumption Rate | Best For | Storage Considerations |
|---|---|---|---|
| Diesel | 0.30-0.40 L/kW/hour | Continuous operation, high loads | Excellent shelf life (1-2 years with stabilizer) |
| Petrol/Gasoline | 0.40-0.55 L/kW/hour | Portable, intermittent use | Short shelf life (3-6 months) |
| LPG (Propane) | 0.25-0.35 L/kW/hour | Clean burning, standby power | Indefinite shelf life, requires pressure tank |
| Natural Gas | 0.28-0.38 L/kW/hour | Continuous, grid-connected | Utility connection required, no storage |
| Load % | Actual Load | Fuel Consumption | Efficiency |
|---|---|---|---|
| 25% | 5 kW | 2.0 L/hour | Standard |
| 50% | 10 kW | 3.5 L/hour | Good |
| 75% | 15 kW | 5.0 L/hour | Optimal |
| 100% | 20 kW | 7.0 L/hour | Good |
Typical consumption: 0.3-0.5 L/kW/hour for diesel generators, 0.4-0.6 L/kW/hour for petrol generators. Consumption increases significantly under higher loads.
Generator Size: 0 kW
Load: 0% (0 kW actual load)
Fuel Type: -
Consumption Rate: 0 L/hour
• 1 hour: 0 L
• 8 hours: 0 L
• 24 hours: 0 L
Note: Consumption may vary based on generator efficiency, altitude, and temperature.
Planning for extended power outages or continuous operation requires accurate runtime calculations. Our runtime calculator determines how long your generator will run based on fuel tank size, generator capacity, and load percentage.
Runtime varies dramatically with load. A generator operating at 50% capacity will run significantly longer than one at full load. Our calculator provides runtime estimates at various load levels to help you plan fuel reserves and refueling schedules.
Understanding operating costs is essential for budgeting. By combining fuel consumption data with local fuel prices, you can accurately estimate hourly, daily, and monthly generator operating costs. This information is crucial for comparing generator options and planning backup power strategies.
| Generator Size | Typical Tank Size | Runtime at 50% Load | Runtime at 100% Load |
|---|---|---|---|
| 5 kW Portable | 15-20 L (4-5 gal) | 8-12 hours | 4-6 hours |
| 10 kW Portable | 25-30 L (6.5-8 gal) | 10-14 hours | 5-7 hours |
| 20 kW Standby | 50-75 L (13-20 gal) | 12-18 hours | 6-9 hours |
| 50 kW Commercial | 200-300 L (53-79 gal) | 18-24 hours | 9-12 hours |
| 100 kW Industrial | 400-600 L (106-158 gal) | 20-30 hours | 10-15 hours |
| Fuel Type | Avg Fuel Price | Consumption Rate | Cost per kW/hour |
|---|---|---|---|
| Diesel | $1.20/L | 0.35 L/kW/h | $0.42 |
| Gasoline | $1.40/L | 0.45 L/kW/h | $0.63 |
| LPG | $0.80/L | 0.30 L/kW/h | $0.24 |
| Natural Gas | $0.70/L equivalent | 0.32 L/kW/h | $0.22 |
Tank Size: 0 liters (0 L)
Generator: 0 kW
| Load | Runtime | Consumption | Cost/Hour |
| 25% (0 kW) | 0 hours | 0 L/h | - |
| 50% (0 kW) | 0 hours | 0 L/h | - |
| 75% (0 kW) | 0 hours | 0 L/h | - |
| 100% (0 kW) | 0 hours | 0 L/h | - |
Note: Runtime calculations are estimates. Actual runtime may vary based on generator efficiency, fuel quality, and operating conditions.