How to choose the right UPS

How do you work out the VA you need?

Add the watts of every device that will sit on the UPS. Processor, graphics card, board and drives together, plus the monitor. Then divide the total by 0.6 to convert watts into VA, and pick the next standard size above the answer.

Worked example. A basic office machine with a modest card and a 24 inch monitor comes to around 210W. Divide by 0.6 and you get 350VA as the minimum, so a 600VA unit is the right buy.

The division accounts for the fact that a UPS rated in VA cannot deliver that many watts. It is the most misunderstood number on the box.

Do you really need a UPS in Delhi?

If the machine holds work you care about, yes. Cuts are shorter than they used to be, and that is not the problem. The problem is what happens either side of one.

A sudden loss of power while a drive is writing is how file systems get damaged and how projects disappear. The surge when supply returns is what takes out power supplies and boards. A UPS smooths both ends.

For a shop counter machine running billing software all day, it is not optional. Losing a day of entries costs more than the unit.

What does a UPS not do?

It does not let you keep gaming through a two hour cut. The battery in a home unit is sized for minutes, not hours, and a gaming PC pulling several hundred watts drains it fast.

It also does not replace a stabiliser for very poor supply conditions, and a basic offline unit does not correct voltage continuously. If your area has severe fluctuation rather than occasional cuts, tell us that, because the right answer is a different class of unit.

Should the monitor be on the UPS as well?

Yes. A running PC you cannot see is no use during a cut, since the whole point is to save your work and shut down. Add the monitor's wattage to your total before sizing.

What should not go on the UPS is the printer. Laser printers draw a large spike when they start, large enough to trip the unit. Plug those into a separate socket.

How long do UPS batteries last?

A few years in normal use, less in a hot room, and heat is the main thing that shortens them. A unit that used to give ten minutes and now gives one has a tired battery rather than a fault.

Most units beep when the battery needs replacing. On many models the battery can be replaced without replacing the whole unit, which is worth asking about before you buy. Bring it in and we will test it rather than guess.

From the counter

People buy a UPS after they have lost something, almost never before. The conversation is always the same: the machine went off mid save, the file is corrupt, and now they want protection for the machine they have just paid to repair.

It is the cheapest part of the whole setup and it is the one that protects everything else.

Frequently asked questions

What is the difference between VA and watts?

VA is apparent power and watts is real power, and for a UPS the relationship is roughly 0.6. So a 600VA unit supports around 360W of actual load, and a 1000VA unit around 600W. Manufacturers advertise the larger VA figure because it looks better. Always size using watts and convert, otherwise you will buy a unit that trips the moment the machine is under load.

How much backup time will I actually get?

Between five and fifteen minutes for a typical home setup, and less the harder the machine is working. That is enough to save what you are doing and shut down cleanly, which is the job. If you need the machine to keep running for an hour, you are looking at a much larger unit with external batteries, and that is a different purchase with a different price.

Can I run a UPS at its full rated capacity?

You should not. Keep the load below about eighty percent of the rating. Running a unit at its limit shortens the battery life, produces more heat and leaves nothing spare for the spikes a PC produces when the graphics card ramps up. This is why the advice is always to go one size up when you are between two options. The price difference is small and the margin is what you are actually buying.

Do I need a UPS if my power supply is a good one?

A good power supply protects the components from a bad mains event. It cannot create power that is not there, so it does nothing about the abrupt shutdown itself, and that is where data gets damaged. The two do different jobs and they work together. A decent supply and a correctly sized UPS is the combination we recommend for any machine holding work that matters.

My UPS beeps constantly. What does that mean?

A beep every few seconds usually means it has switched to battery because mains input is out of range. A continuous alarm usually means overload or a failed battery. Unplug non essential devices first and see whether the alarm clears, which tells you it was overload. If it continues with only the PC connected, the battery is the likely cause. Bring the unit in and we will test it rather than replacing parts on a guess.

We do not list UPS units on the site. We stock them at the counter, so come in with your total wattage and we will size one with you.

Read next

• How to choose the right SMPS
• How to choose the right storage
• How to choose the right processor

Written by Shreyansh Jain, who runs Get Right PC and is second generation in Nehru Place. Published 2026-09-24. Last updated 2026-09-24.