Here’s How to Calculate the UPS Power Rating You Need [Guide]

With summers here, and extremely hot temperatures in most parts of the country, Pakistanis are bracing for the worst. This season, just like the other summers before it, results in an ever widening gap between rise and demand in power supply. Loadshedding continues to increase in all parts of the country.

Considering that even when Pakistan attained maximum power capacity a few days ago, the power shortfall was still a whopping 3,000MW across the country. It’s bound to go higher as temperatures get higher and demand increases.

Given this woeful state of affairs, it is a good idea to opt for a generator or an Uninterrupted Power Supply (UPS) unit in order to beat the heat. For this purpose, I’m going to discuss UPS units and which one is perfect for your household/office needs.

The UPS Has Come a Long Way

Until a few years ago, UPS systems were only used to power the lights and fans since loadshedding was lesser. However, thanks to the increasing hours of power blackouts and the demands of our modern lifestyles, these days home appliances and other electrical equipment also need to be connected to the UPS.

To meet the electrical requirements of such equipment you need to know the maximum capacity of your UPS.

It might be simple enough for most engineering students, but for the rest, we have prepared a guide to calculate the appropriate wattage for your new UPS. You only need to add the wattage of electrical items you want to connect with a UPS so that you can buy one with the right power capacity.

Lets take a look at how much watts your normal electrical items consume.


  • Normal Energy Saver – 20W-24W
  • Small Energy Saver – 6W-13W
  • Large Energy Saver – 33W-45W
  • LED Energy Saver – 9W-15W
  • Tube Light – 35W-45W
  • Small Tube Light – 10W-20W
  • Filament Bulb – 60W-100W
  • High Wattage Bulb – 200W-500W

It’s a good idea to check the wattage mentioned on the packaging when purchasing your lights.

Household Equipment

  • New Fans – 110W-120W
  • Old Fans – 150W-200W
  • Iron – 1000W
  • Microwave – 400W-1500W
  • Up to 27-inch LCD TV/Monitor – 45W-65W
  • Large Screen LCD TV – 55W-110W
  • Up to 27-inch LED TV/Monitor – 35W-45W
  • Large Screen LED TV – 45W-90W
  • CRT TV/Monitor – 150W-300W
  • Room Refrigerator – ~150W
  • New Refrigerator – 250W-500W (depending on its size)
  • Old Refrigerator – 400W-700W
  • Deep Freezer – 400W-900W
  • Water Dispenser – 100W(Cooling), 500W(Heating)
  • Small Water Motor – ~300W
  • Large Water Motor – 500W-700W
  • Air Conditioners (AC) – 1500W-2800W [2200W to 3700W when it starts] (Depending on size)
  • Inverter AC – 250W-2000W (Depends on desired temperature and size)
  • Electric Heater (Blower) – 800W-1000W
  • Electric Heater (Lamp/Filament) – 400W per lamp


  • Normal Phone Charger – 5W (when charging)
  • Phone Fast Charger – 20W-25W (when charging)
  • Laptop – 40W-50W (Normal usage)
  • Gaming Laptop – 70W-120W
  • Desktop PC excluding monitor– 100W-500W (depending on light or heavy usage)
  • Router/Modem – 5W-10W
  • Printer – 450W

How to Calculate

To calculate the amount of power you would be consuming via a UPS, you need to make a list of all the items you want to back up with it and add their respective wattages (hint: you can use the guide above or check the labels on the electronic items you wish to connect).

Once you get the total wattage, multiply it by 1.5 (to compensate for the theoretical VA mentioned on a UPS) and you will get the maximum UPS wattage you require. VA value is the basically the maximum capacity/power rating of a UPS.

For example:

You have a 32-inch LED TV, laptop, 5 energy savers, 5 new fans and a refrigerator. You can calculate using a similar formula by adding wattages for each item and multiplying it by 1.5 (the factor varies between 1.3 to 1.6 depending on the quality of the UPS). In this case:

Total UPS Wattage Required = (65W+40W+5×23+5×120+350W) x 1.5 = 1,755W

Therefore, you will need a UPS with a maximum wattage of over 1,755 Watts. Since a UPS of that size is not available, you would need a 2000 VA UPS.

Try to buy a UPS with more a higher power rating than what you require to be on the safe side and for less heating issues.

For my next post, I’ll go into detail with UPS battery sizes and which one is the best for you.

This is the first in a series of posts that will be featured on ProPakistani to guide the common man regarding UPS, Batteries, Solar Panels and more.

Have something to say or want to know more about this? Drop an email at [email protected] or find Aadil Shadman on Twitter (@ashadman25) or Facebook(

He is the Chief Content Officer at ProPakistani. Reach out at aadil.s[at]

  • Watts and VA are not the same, specially if there are fans and motors in the calculation.
    Normally the power factor is around 0.8 on average so 2000VA = 0.8 x 2000 = 1600 Watts.

      • for simplicity we can define the formula as:
        P (Power in Watt) = Voltage(V) x Current(A) x power factor
        Watt = VA x power factor

        this power factor is 1 in case of resistive load (eg. light bulbs and heaters)
        but is less than 1 in case of inductive load (e.g fans and motors)

        So if there are alot of fans and motors the overall power factor will be less (like 0.5) so the Watts will be less for a particular rated VA UPS.
        0.8 is the usual average its not fixed, can be more or less depending on the load.

    • You are right but you probably need to work on the x 0.8 formula, as my 2000va Homage UPS says it can support 1200 Watts. So I think its more like 0.6 than 0.8.. But the exact value may vary depending on appliances and can be found by VoltagexAmps mentioned on them.

    • That’s the minimum power usage when an inverter AC reaches the desired temperature.

  • Rating of UPS depends upon power factor (P.F). PF varies from UPS to UPS, three types of UPS are available in market, Pure sine wave, Approximately sine wave, modified sine wave there power factors are 0.9, 0.8, 0.6 respectively.
    Power (W) = VA x PF

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