Calculate Inverter VA Rating, Battery Capacity & Backup Time
💡 Formulas: VA = (W × PF) / Eff | Ah = (W × Hrs) / (V × DOD)
VA = (W × PF) / Eff | Ah = (W × Hrs) / (V × DOD)
📖 Inverter Size Calculator
This tool helps you select the right inverter for your home, office, or solar system. It calculates the required inverter VA rating, battery capacity (Ah), and provides recommendations based on your load and backup requirements.
📐 Inverter Sizing Formulas
Inverter VA: VA = (Load × PF) / Efficiency Battery Ah: Ah = (Load × Hours) / (Voltage × DOD) Inverter Watt: W = VA × PF
📊 Standard Inverter Sizes
Inverter (VA)
Load (W)
Application
300 VA
250
1 Fan + 2 Lights
600 VA
500
2 Fans + 4 Lights
850 VA
720
Small Home Office
1000 VA
850
1 Room + TV
1500 VA
1275
2 Rooms + TV
2000 VA
1700
Small House
3000 VA
2550
Medium House
5000 VA
4250
Large House / Shop
10000 VA
8500
Commercial / Workshop
📌 Inverter Types
Square Wave: Basic, cheap, not for sensitive electronics
Modified Sine Wave: Good for most appliances
Pure Sine Wave: Best for all devices, recommended
Solar Hybrid: Grid-tied with battery backup
Off-Grid: For standalone solar systems
💡 Inverter Sizing Tips
Calculate total load: Sum all devices for power cut
Add 25% margin: Inverter should be larger than load
Consider starting current: Motors have 3-5× starting current
Pure sine wave: Essential for TVs, computers
❓ Frequently Asked Questions
How to size an inverter for home? ▼
Calculate total load, add 25% margin, divide by PF to get VA rating. This calculator does it automatically.
What inverter size for 500W load? ▼
For 500W at 0.85 PF, you need 500/0.85 = 588 VA. Choose 600-850 VA inverter.
VA vs Watts difference? ▼
VA is apparent power, Watts is real power. VA = Watts / PF. Inverter rating is in VA.
How to calculate battery Ah? ▼
Ah = (Load × Hours) / (Voltage × DOD). For 500W for 3hrs at 48V with 90% DOD: Ah = (500×3)/(48×0.9) = 34.7 Ah.
Pure sine vs modified sine wave? ▼
Pure sine wave is essential for TVs, computers, and modern electronics. Modified sine wave works for fans and lights.