Starting vs. Running Watts Calculator
Determine continuous running wattage and initial motor startup surge power. Accurately size your backup generator for refrigerators, AC units, sump pumps, and air compressors.
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Quick Add Common Items
Your Load List
| Item | Running | Starting | |
|---|---|---|---|
| Add items to calculate sizing. | |||
Required Generator Size
Calculation Logic: Total Running Watts + Highest Single Additional Surge. This assumes all items run at once, but only the largest motor starts while others are running.
Surge Visualizer
Starting vs. Running Watts Formula & Chart
Inductive motor loads (compressors, pumps, blowers) require an initial burst of surge power (up to 3x–4x continuous watts) for 1–3 seconds to break mechanical inertia.
Standard Generator Sizing Formula
| Appliance / Equipment | Load Type | Running Watts | Starting Watts | Surge Multiplier |
|---|---|---|---|---|
| ❄️ Refrigerator / Freezer | Inductive | 700 W | 2,200 W | 3.1x |
| 💨 Central AC (3.5 Ton) | Inductive | 3,500 W | 10,500 W | 3.0x |
| 🛠️ Air Compressor (2 HP) | Inductive | 2,000 W | 5,000 W | 2.5x |
| 💧 Sump Pump (1/2 HP) | Inductive | 1,050 W | 2,200 W | 2.1x |
| 🚰 Well Pump (1 HP) | Inductive | 2,000 W | 5,000 W | 2.5x |
| 🍕 Microwave Oven | Resistive | 1,500 W | 1,500 W | 1.0x |
| 🔥 Space Heater (Portable) | Resistive | 1,500 W | 1,500 W | 1.0x |
| 🪚 Circular Saw (7-1/4") | Inductive | 1,400 W | 2,300 W | 1.6x |
Recommended Gear for Motor Surge Management
Essential soft start kits, power monitoring meters, heavy-duty extension cables, and surge-capable inverter generators.
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Dual-Fuel Inverter Generator
High starting surge capacity inverter generators with low total harmonic distortion (THD) for sensitive electronics.
Micro-Air EasyStart Soft Start Kit
Reduces AC and heat pump startup surge inrush current by up to 70%, enabling smaller generator operation.
Kill-A-Watt Usage & Power Monitor
Displays real-time running watts, VA, voltage, and line frequency for home appliances and tools.
10/3 Heavy-Duty Outdoor Extension Cord
Weatherproof 10-gauge pure copper extension cable prevents voltage drop under high motor surge loads.
Compressor Hard Start Capacitor Kit
Delivers 500% starting torque boost to older compressors, easing generator startup burden.