Use this calculator for any appliance with known wattage and usage hours.
🔌
Universal Appliance Calculator
Use this for any device when wattage and usage time are known.
Live calculator
Input Details
Fill what you know. If a value is unknown, keep the practical default and verify the nameplate later.
How do I calculate the total wattage (load) of my house?
Short answer: Add up the watts of every appliance that can run at the same time. Example: 4 fans (300 W) + 6 LED lights (60 W) + fridge (200 W starting) + TV (100 W) + 1.5 ton AC (1,600 W) = about 2,260 W or 2.3 kW connected load. Amps = watts ÷ voltage: 2,260 W ÷ 230 V ≈ 9.8 A in India, the UK and Europe, or ÷ 120 V ≈ 18.8 A in the US. Use this peak load to size an inverter, solar system, generator or sanctioned load; use kWh (watts × hours) for the bill.
Sizing guide from total load
Use
What to size by
Rule of thumb
Inverter / UPS
Running watts of backup appliances
VA ≈ watts ÷ 0.8
Sanctioned / connected load
Sum of all appliance watts
Add 20–25% margin
Rooftop solar
Monthly kWh
1 kW ≈ 120 kWh/month in India
Generator
Running watts + largest motor start
Motors start at 2–3× running watts
Tip: Motors and compressors (AC, fridge, pump) draw 2–3 times their running watts for a few seconds at start-up; include that when sizing inverters or generators.
By Harshad Kumar Sharma · Last reviewed · Method: kWh = watts × hours × days ÷ 1,000
How do I calculate the power consumption of an appliance?
Short answer: kWh per month = watts × hours per day × days ÷ 1,000. Monthly cost = kWh × your tariff. Example: a 100 W device used 4 hours a day for 30 days uses 12 kWh; at 8 per kWh it costs 96 a month.
Typical wattage of home appliances
Appliance
Typical watts
kWh per hour of use
LED bulb
7–12 W
0.01
Ceiling fan (normal / BLDC)
70–80 W / 28–35 W
0.075 / 0.03
LED TV 43"
60–90 W
0.08
Laptop / Wi-Fi router
45–65 W / 6–12 W
0.05 / 0.01
Refrigerator (average)
~40–120 W avg
0.04–0.12
Washing machine
400–1,000 W
0.5 per cycle
Microwave / induction
1,100–2,000 W
1.2–2.0
1.5 ton AC
1,100–1,600 W
1.1–1.5
Geyser / water heater
2,000–3,000 W
2.0–3.0
Tip: Nameplate watts are a maximum; thermostat appliances (fridge, AC, heater, iron) use less on average.
Using this calculator outside India? Outside India? Pick your currency at the top of the page and enter the per-kWh rate printed on your bill. Typical residential averages: USA 18.3¢/kWh (EIA, July 2026; California 33.6¢, Texas 15.9¢), UK about £0.25/kWh, Germany about €0.38/kWh, UAE about AED 0.23–0.38/kWh, Canada about C$0.13–0.20/kWh and Australia about A$0.30–0.35/kWh. The kWh result is the same in every country; only the cost changes.
By Harshad Kumar Sharma · Last reviewed · Method: kWh = watts × hours × days ÷ 1,000
Monthly units = watts × hours/day × days/month × quantity ÷ 1000. Use actual nameplate wattage for better accuracy.
This is a preliminary planning estimate. For certified audits, use site measurement and nameplate readings.
FAQ
How many units does 1,000 watts use in one hour?
1,000 watts running for one hour uses exactly 1 kWh, which is 1 unit on an electricity bill.
How do I find the wattage of an appliance?
Check the rating label or nameplate on the back or bottom of the appliance, or the user manual. If only volts and amps are given, watts ≈ volts × amps. A plug-in energy meter shows the real running watts.
How do I convert watts to amps?
Amps = watts ÷ voltage. Use 230 V for India, the UK, Europe, the Middle East and Australia, and 120 V for the US and Canada. A 2,000 W geyser draws about 8.7 A at 230 V.
What is the difference between kW and kWh?
kW is power, how much an appliance draws at a moment. kWh is energy, power multiplied by time. Your electricity bill charges for kWh (units); your sanctioned or connected load is in kW.
Can I calculate any device?
Yes, if you know approximate wattage and usage time.
What if appliance cycles on/off?
Use average wattage or duty-cycle adjusted wattage instead of full rated wattage.
Universal tool tip
Use this page for any device not listed elsewhere. Enter wattage, quantity and actual runtime for best results.
Accuracy note
The result is a planning estimate. Use nameplate wattage, measured runtime and current tariff for professional-level accuracy.