Laptop UPS Runtime Calculator. Choose the Best Battery Backup

As we rely more on our computers or laptops for work and study, it is crucial that we have the means to keep our devices powered on and connected. One popular gadget right now is the uninterruptible power supply (UPS).

The UPS is usually used by desktop computer owners as it gives them time to save their work in case of a power interruption. It also helps protect their computer setup in case of a power surge.

For laptop users, the use of UPS may seem redundant, since laptops have their own batteries and can stay powered on for hours. But laptop users can also benefit from using a UPS.

Some benefits of using UPS for laptops include:

  • Longer battery life during power outages
  • Protection against power surges and dips
  • Allows you to plug in additional devices even during an outage

In some cases, people prefer their laptops plugged into a power source with the battery removed. This may save their battery from early deterioration, but it can be problematic when there’s a sudden power outage. Using a UPS can save you from a lot of problems and headaches.

There are a lot of different types of UPS available in the market, but not all of them may be compatible with your laptop. You also have to consider how much power your laptop uses to determine the type of UPS you would need.

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Laptop UPS Runtime Calculator

Before clicking that buy button, first, you need to check the UPS runtime by using an uninterruptible power supply calculator. 

But before that, you need to familiarize yourself with some terms that you need to check on the UPS and the laptop you will be plugging in.

Terms to remember

Battery capacity (AH) – ampere per hour is the measure of how much charge a battery can store; it can be seen on your laptop battery and on the UPS

VA Power Rating (VA) – VA or Volts*Amps is the maximum charge of the battery; it is the max power your UPS can hold

Watts Power Rating (W) – the actual power output of the UPS 

Total load (Wt) – the sum of the power consumption of all the devices that will be plugged into the UPS

UPS runtime formula

To calculate the UPS runtime when using a laptop, you can use the following formulae:

Time = AH / A

A = Wt/V

Assuming you are using a laptop with a power draw of 60W, and it will be the only thing you’re plugging into your UPS, this will serve as your Wt. You will need a UPS with 100W or higher.

If you have a UPS with a 12V battery, a battery capacity of 2.9AH, and a Watts Power Rating of 300W, it can support the power demand of your laptop. The question now is, how much time do you have to put the battery pack back in your laptop so you won’t lose your work?


Wt – 60W

V – 12V

AH – 2.9AH

W – 300W

Formula 1: A = Wt/V

A= 60W/12V

A = 5

Formula 1: Time = AH/A

Time = 2.9AH/5A

Time = 0.58 hours

For more context, you can convert hours to minutes by using this formula:

Formula 3: Minutes = Hours (60 minutes/1 hour)

Minutes = 0.58 hours (60 minutes/1 hour)

Minutes = 34.8 minutes

Based on the calculations above, the UPS will keep your laptop powered for 34.8 minutes. It will give you enough time to save your work.

UPS runtime calculator

Calculating how long a UPS will last can be a tedious task for some, plus in some cases, all the data you need are not readily available, which means more computation will be needed.

APC UPS runtime tool

The American Power Conversion Corporation or APC offers a runtime tool to help you select which UPS to get. In APC’s UPS selector, you just need to know the power draw of your device.

For laptop users, choose Home, Home Office and Small Business then click Configure by Device. Next, choose PC/Laptop from the selection provided. 

Select the model and quantity of the devices you are going to use the UPS for. Choose Unlisted if the model or device is not on the list. In this case, select 1 for the quantity since you’ll only be using it for a laptop. Input the power draw of your laptop, which in the example above is 60W.

Click add. It will then tell you the voltage of the UPS you need. In this case, a UPS with a 230V will be sufficient. Click Continue.

APC will then show you a list of UPS with their runtimes based on the parameters you submitted. The higher the VA, the longer the UPS lasts.

Best selling UPS

No products found.

One of the top-rated UPS is the No products found. that has a backup battery and surge protector. It has a total of 10 outlets, 5 of which have surge protection and battery backup, while the other 5 only offer surge protection.

If you plug in a device with a power draw of 100W, the runtime for the APC UPS 1500VA is 1 hour and 8 minutes. It has an LCD display that helps you see how much power you have left before the UPS shuts down.

No products found.

Another highly rated UPS is the No products found.. It has 12 outlets, 6 outlets with surge protection and battery backup, and 6 outlets with only surge protection. 

The 15000VA/900W battery can handle a single laptop plugged in but if it’s fully loaded, the runtime is 3 minutes. If only half the load is plugged in, this UPS can last for 12 minutes.

No products found.

The No products found. is a UPS that features a 1500VA/900W battery. If you plug in a 75W device, it can keep it on for 90 minutes. If you plug devices that total 450W, it can last up to 10 minutes.

It has a total of 10 outlets, 5 with backup power and surge protection, and 5 with only surge protection.


Power outages or power fluctuations can damage our electronic devices or worse, make us lose our work. To prevent this, the use of an uninterruptible power source has grown in popularity even with laptop users.

Make sure you choose the right UPS, taking note of the total load you will plugin before making a purchase. Just remember, UPS are not meant to power up your devices for hours, but give you time to power down your devices properly and protect against power surges.