Inverter Load Calculator - VA & Battery AH from Appliance Load
Size inverter VA and battery AH from your total appliance load - add custom wattages, use 1BHK/2BHK/3BHK or bedroom presets, and set backup hours for instant VA and amp-hour recommendations. Supports India, US, and EU quick-start configurations.
Total Load
340W
Suggested
850VA
Backup
4.5 Hrs
Recommended Battery
150 AH (12V)
System Setup
Region, housing preset, and backup settings
Region
Quick Presets
Appliance Management
Configure your load requirements
LED Bulb
Standard energy-efficient lighting
Ceiling Fan
Standard 48-inch ceiling fan
LED TV
32-43 inch LED television
Wi-Fi Router
Home internet router
Laptop Charger
Laptop power adapter
Methodology and limitations
Last reviewed:
Methodology
Sums appliance wattage by quantity, applies power factor and safety margin for inverter VA, and divides energy demand by battery voltage and efficiency for AH. Results round up to standard market sizes.
Limitations
Motor startup surge, cable losses, battery aging, and temperature can affect real-world performance. Consult an installer for final sizing.
How Inverter VA and Battery AH Are Sized
Size inverter VA and battery AH from your total appliance load - add custom wattages, use 1BHK/2BHK/3BHK or bedroom presets, and set backup hours for instant VA and amp-hour recommendations. Supports India, US, and EU quick-start configurations.
Method used
The calculator sums running appliance wattage, converts to inverter VA using power factor and a safety margin, then divides energy demand by battery voltage and efficiency to recommend amp-hour capacity for the selected backup hours.
VA = (total watts ÷ power factor) × safety margin; AH = (watts × backup hours) ÷ (voltage × efficiency)
Practical example
A 1BHK load of 450 W with 0.8 power factor, 1.2 safety margin, 4 backup hours, 12 V battery, and 85% efficiency might suggest roughly 850 VA inverter and 180 AH battery (rounded to market sizes).
- Appliance list with wattage and quantity
- Backup hours, battery voltage, power factor
- Housing preset or custom load
The result shows total load watts, recommended inverter VA, battery AH, and rounded standard market sizes.
Assumptions
- All listed appliances may run simultaneously unless you adjust the load.
- Power factor defaults to 0.8 for mixed household loads.
- Results round up to common inverter and battery sizes.
What this includes
- Load wattage total, inverter VA sizing, battery AH sizing, housing presets, and advanced efficiency settings.
What this excludes
- Motor startup surge beyond steady-state VA, cable voltage drop, battery aging, solar charging integration, and installer-certified final design.
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Frequently Asked Questions
How do I calculate inverter VA from appliance load?
Add the wattage of all appliances running at the same time, divide by the power factor (typically 0.8 for mixed household loads), and apply a safety margin. The calculator rounds up to standard inverter sizes such as 600, 850, or 1000 VA.
How is battery AH calculated for backup power?
Multiply total load in watts by desired backup hours, then divide by battery voltage and inverter efficiency. For conservative sizing, enable depth-of-discharge in advanced settings.
What is the difference between VA and watts?
Watts measure real power consumed by appliances. VA (volt-amperes) is the apparent power an inverter must supply. Motors and inductive loads draw more VA than watts, so inverters are rated in VA.
Should I use 12V, 24V, or 48V batteries?
12V systems are common for small homes and apartments. 24V and 48V suit larger loads because they reduce current and cable losses. Match your battery bank voltage to your inverter rating.
What are 1BHK, 2BHK, and 3BHK presets?
These are India-style housing presets (1, 2, or 3 bedroom-hall-kitchen units) that pre-fill typical appliance loads. US and EU presets use bedroom-based labels with region-appropriate wattages.
Do motors need extra inverter capacity?
Yes. Refrigerators, air conditioners, and pumps can draw 2-3* their running watts at startup. Choose an inverter with adequate surge capacity beyond the steady-state VA shown here.