Inverter VA = (W × PF) / Eff | Battery 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. Essential for home UPS, solar, and power backup planning.
📐 Inverter Sizing Formulas
Inverter VA: VA = (Load × PF) / Efficiency Battery Ah: Ah = (Load × Hours) / (Voltage × DOD) Inverter Watt: W = VA × PF
Where: Load = Connected Load (Watts) PF = Power Factor Efficiency = Inverter Efficiency (%) DOD = Depth of Discharge (%) V = Battery Voltage (V) Hours = Required Backup Time
📊 Standard Inverter Sizes
Inverter (VA)
Load Capacity (W)
Typical 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 suitable for sensitive electronics
Modified Sine Wave: Good for most appliances, affordable
Pure Sine Wave: Best for all devices, recommended for modern electronics
Solar Hybrid Inverter: Grid-tied with battery backup
Off-Grid Inverter: For standalone solar systems
💡 Inverter Sizing Recommendations
Calculate total load: Sum all devices you want to run during power cut
Add 25% margin: Inverter should be 25% larger than calculated load
Consider starting current: Motors (fans, AC, fridge) have 3-5× starting current
Select battery voltage: Higher voltage = lower current = less loss
Pure sine wave: Essential for TVs, computers, and modern electronics
Check warranty: At least 2-3 years warranty recommended
🔧 How to Use This Calculator
Enter total load (watts) - sum of all devices
Enter power factor - typical 0.85 for home appliances
Enter required backup time - in hours
Select battery voltage - 12V, 24V, 48V, 96V
Select DOD - based on battery type
Select inverter efficiency - 85-95%
Results include recommended inverter VA, battery Ah, and next standard sizes
❓ Frequently Asked Questions (FAQ)
❓ How to size an inverter for home? ▼
Calculate total load in watts, add 25% margin, then divide by PF to get VA rating. This calculator does this automatically.
❓ What inverter size for 500W load? ▼
For 500W load at 0.85 PF, you need 500/0.85 = 588 VA. Choose 600-850 VA inverter for safety.
❓ What is the difference between VA and Watts? ▼
VA is apparent power, Watts is real power. VA = Watts / PF. Inverter rating is in VA, load is measured in Watts.
❓ How to calculate battery Ah for inverter? ▼
Ah = (Load × Hours) / (Voltage × DOD). For 500W load for 3 hours at 48V with 90% DOD: Ah = (500×3)/(48×0.9) = 34.7 Ah.
❓ What is the recommended inverter efficiency? ▼
Good inverters have 90-95% efficiency. Higher efficiency means lower energy loss and less heat generation.
❓ Pure sine wave vs modified sine wave - which is better? ▼
Pure sine wave is essential for TVs, computers, and modern electronics. Modified sine wave works for fans, lights, and heaters.