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Inverter Size Calculator

Calculate the right inverter and UPS capacity in Watts and VA to run your essential home appliances without overloading.

Calculator Inputs

Live
W
100 W10,000 W
Calculation Results
Recommended Inverter Rating
1,875 VA
Minimum Continuous Watts: 1500W (with 25% surge margin)
Recommended DC Voltage
12V DC
Running Base Load
1200 Watts
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How to use the Inverter Size Calculator

  1. 1Enter total simultaneous continuous appliance power in Watts.
  2. 2Set safety buffer margin (default is 25% to accommodate motor starting surge).
  3. 3Adjust power factor (standard is 0.8 for domestic inductive loads).
  4. 4View recommended inverter continuous Watts, VA rating, and recommended DC voltage.

How Inverter Size is Calculated

Continuous wattage is increased by a safety margin for surge capacity, then divided by the appliance power factor to find the necessary Volt-Amp (VA) inverter rating.

Mathematical Formula
Inverter Watts = Total Continuous Watts × (1 + Safety Margin % / 100) Inverter Rating (VA) = Inverter Watts / Power Factor
Formula Variables & Logic

Motors and compressors in refrigerators, pumps, and fans require 2-3x their rated wattage momentarily when starting up.

Worked Example: Home Power Inverter
Sample Calculation
Scenario: Running 3 ceiling fans (210W), 6 LED lights (60W), 1 TV (100W), and 1 refrigerator (250W) totaling 620 Watts continuous.
Step-by-step breakdown
  1. 1Continuous Watts = 620W
  2. 2With 25% safety surge buffer = 620 × 1.25 = 775 Watts
  3. 3VA Rating = 775 / 0.8 = 968.75 VA -> Recommend a 1,000 VA or 1.1 kVA inverter.
Estimated Result
A 1,000 VA (1 kVA) pure sine wave inverter running on a 12V or 24V system is recommended.

What affects Inverter Size results

  • Inductive motor surge loads from air conditioners, submersible pumps, and refrigerators.
  • Pure Sine Wave vs Modified/Square Sine Wave output waveform.
  • Continuous inverter operating efficiency.
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Frequently Asked Questions

What is the difference between Watts and VA in inverters?

Watts represents real power consumed by appliances, while VA (Volt-Amps) represents apparent power. Inverter models are commonly sold by their VA rating (Watts = VA × Power Factor).

Why should I choose a Pure Sine Wave inverter?

Pure Sine Wave inverters deliver clean AC power identical to the electrical grid, preventing humming noises in fans and protecting sensitive electronics and motors.

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