Skip to content

Topology first, then the gap between the VA figure and the watt figure

The best UPS units for 2026

An uninterruptible power supply keeps a machine running long enough to shut it down properly, and the specification opens on a distinction that accounts for half the price. In a standby unit the load runs from the mains until the mains fails, and a relay hands over to the inverter within a few milliseconds. A line-interactive unit adds a transformer that corrects a supply which is merely low or high without calling on the battery at all, which counts for a great deal on a weak line. An online unit runs the load from its inverter permanently and has no transfer time. IEC 62040-3 gives these arrangements formal classifications, and the maker states which one applies. Then the two capacity figures, which are not the same number. VA is apparent power and watts is real power; the watt figure is always the smaller of the two and is the one a computer's consumption has to fit inside. Runtime charts are published against a load in watts, so a runtime quoted without its load says nothing at all. The waveform on battery is either a stepped approximation or a sine wave, and some power supplies with active correction object to the former — on that point the maker of the computer, not of the UPS, is the source. Count the sockets and note which are battery-backed and which only filtered, then read the battery type and whether the pack is user-replaceable. We compare topology and its stated classification, VA and watt ratings, stated runtime at a named load, output waveform, socket count and type, battery type and replaceability, and communication port.

By

The ones worth installing

  1. APC BE425M, 425 VA with a wiring-fault lamp and 15 minutes at 100 W

    topology not published · 425 VA and 255 W · 15 minutes at 100 W · waveform not published · six NEMA outlets, four on battery · 180 joules · building wiring fault indicator · three years and $75,000 cover

    The lowest price on this shelf, with a runtime at a named load, a joule rating and a lamp that warns about the wiring in the wall — and neither its topology nor its waveform.

    Best for: A router and a modem in a flat where the socket is somebody else’s work and the wiring lamp earns its keep.

    ≈ $63

    Check price on Amazon Read the review: APC BE425M, 425 VA with a wiring-fault lamp and 15 minutes at 100 W

  2. APC BX1350M, 54 minutes at 100 W and the only efficiency figure on this shelf

    topology not published · 1350 VA and 810 W · over 54 minutes at 100 W · ten NEMA outlets, five on battery · coaxial and Ethernet surge protection · AVR from 88 V, ±13 per cent · ENERGY STAR at 92 per cent · battery APCRBC123 named

    The longest runtime on this shelf at over fifty-four minutes, the only efficiency figure here, and the only listing that names compatibility with an actively corrected power supply.

    Best for: A desk that has to keep working through an outage rather than shut down during one, with an actively corrected power supply in the computer.

    ≈ $205

    Check price on Amazon Read the review: APC BX1350M, 54 minutes at 100 W and the only efficiency figure on this shelf

  3. APC BE900G3, a 6 ms transfer time and USB-C charging on the front

    standby · 900 VA and 540 W · 21 minutes at 150 W, 100 minutes for network devices · eight NEMA outlets, six on battery · USB-C and USB-A at 5 V 3 A · 490 joules · transfer in 6 ms · PowerChute Serial Shutdown named · battery RBC17

    The only listing on this shelf that publishes how fast it switches to battery — six milliseconds — and the only one with USB-C charging on the front.

    Best for: A desktop machine and a router on the same unit, where the six-millisecond transfer and the two runtime figures are what the money is for.

    ≈ $164

    Check price on Amazon Read the review: APC BE900G3, a 6 ms transfer time and USB-C charging on the front

  4. Eaton 5S700G, 230 V and six IEC C13 sockets — on an American listing

    line-interactive · 700 VA and 420 W · runtime not published · six IEC C13 at 230 V, not NEMA · AVR from 175 to 275 V · LCD with load, battery time, voltage and event log · USB with Windows, macOS and Linux software · fanless · RJ45 surge protection

    A 230-volt European unit with six IEC C13 sockets, sold on an American shop — and the only listing on this shelf with a screen, a Linux-capable shutdown client and an idle-peripheral cut-off.

    Best for: A 230-volt installation — not an American wall socket — where a screen, an event log and Linux shutdown support are the reasons to choose it.

    ≈ $196

    Check price on Amazon Read the review: Eaton 5S700G, 230 V and six IEC C13 sockets — on an American listing

  5. Tripp Lite AVR900U, two waveforms for two modes and a USB cable in the box

    line-interactive · 900 VA and 480 W · pure sine in mains mode, PWM sine on battery · twelve NEMA outlets, six on battery · AVR from 89 to 145 V · USB and cable supplied with shutdown software · battery RBC51 named

    The only listing on this shelf that publishes a different waveform for mains mode and for battery mode, with the 89–145 V window its regulator corrects and a USB cable already in the box.

    Best for: A computer that must save and shut down by itself, where knowing the battery-mode waveform and the regulation window matters more than a runtime figure.

    ≈ $150

    Check price on Amazon Read the review: Tripp Lite AVR900U, two waveforms for two modes and a USB cable in the box

  6. Tripp Lite BC850RNC, cloud alerts by email or text and configuration over NFC

    standby · 850 VA and 450 W · runtime not published · five outlets, split not stated · 190 joules · email and text alerts through a cloud app · NFC and QR configuration · battery AG-0761 named · 100 × 100 mm (3.94 × 3.94 in) VESA

    The only listing on this shelf that names email and text alerts when the power fails, configured by holding a telephone against it — and the only one that gives its wall mounting as a VESA pattern.

    Best for: A kiosk, a till or a camera in a building nobody is standing in, where being told by text message is worth more than a longer runtime.

    ≈ $175

    Check price on Amazon Read the review: Tripp Lite BC850RNC, cloud alerts by email or text and configuration over NFC

  7. APC SMC1500-2UC, 2U rackmount with cloud monitoring and a warranty split in three

    line-interactive · 1500 VA and 900 W pure sine wave · runtime not published · six NEMA 5-15R out, NEMA 5-15P in · 2U rack with rails · cloud portal with notifications and firmware · 2 years plus 2 years battery plus 1 more if registered · $150,000 cover

    The only rackmount unit on this shelf, publishing a pure sine wave, its input plug as well as its outputs, and a warranty split three ways — on a page whose cloud service is free for six months in one place and two years in another.

    Best for: A cabinet that already holds the switch and the network drive, where the rails, the sine wave and the remote firmware are the reasons to spend four times the money.

    ≈ $784

    Check price on Amazon Read the review: APC SMC1500-2UC, 2U rackmount with cloud monitoring and a warranty split in three

The need before the model, across UPS units

Keep a server up mid-write

The watt rating is the only figure that describes what the unit genuinely supports; the VA figure exists to name the product.

APC Smart-UPS SMC1500-2UC

Allow time for a clean shutdown

The stated runtime at a named load only means anything with that load. On a NAS mid-write, those minutes are the entire point.

APC Back-UPS Pro BX1350M

Who buys what, across UPS units

A machine running with nobody in front of it
The published topology decides what happens at the instant of the cut. On headless equipment, nobody will be there to notice.
Network gear to connect
The published socket type decides what plugs in without an adapter. A lot of network kit arrives with a bulky power brick.
Placing a model in the range
The published stated classification places the unit in the maker’s hierarchy. It is a range marker, not a measurement.

Nothing is free: the trade-offs of UPS units

Watts against VA
The gap between the two published figures is systematic and never zero. Taking the flattering one means buying short.
Double conversion against permanent draw
The most protective topologies work continuously and draw all year, on a unit that never switches off.
Runtime against weight to carry
Extending the runtime means stacking batteries. In a rack, that is counted in kilos on a shelf.

Buyers’ questions on UPS units

Why do VA and watts differ?

VA expresses apparent power, watts real power. Both are published, and only the second is used for sizing.

What does the published topology change?

It describes the mode of intervention: standby, continuous regulation, or double conversion. It governs the behavior at the moment of transfer.

Does the stated runtime apply to my load?

Only to the load named beside it. A heavier load cuts the runtime faster than in proportion.

Is the output waveform a problem?

Some switching power supplies cope badly with it during the transfer. It is published and read alongside the topology.

Are all sockets on battery?

Socket count and socket type are published, but the split between backed-up and merely filtered sockets depends on the model.

Is software needed to shut the server down?

An automatic shutdown assumes a link and software on the machine. This site publishes the product’s hardware characteristics.

What does the stated classification denote?

The range name the maker gives the model. It is published and replaces no power figure.

How long do these batteries hold out?

Replacement and lifespan depend on the model and the use. This site reports published characteristics without deriving a deadline.

What to take away from UPS units

A rack UPS is sized on watts and judged on its topology. The runtime means nothing detached from its named load, and socket count decides whether the whole rack sits behind it.

The gist of UPS units, at a glance

  • On Amazon.com on October 26, 2026: 7 of the 7 models had an offer, from $63 to $784.
  • Lowest Amazon.com price on October 26, 2026: APC Back-UPS BE425M, at $63.
  • Stated runtime at a named load: 15 to 54 minutes, on 3 of the 7 models.
  • Highest figure for VA rating: APC Smart-UPS SMC1500-2UC (1500 VA — stated in the title and in the first bullet).
  • Highest figure for watt rating: APC Smart-UPS SMC1500-2UC (900 W — stated in the title and in the first bullet, which puts the ratio at 0.60).

A comparison of UPS units

The table shows only the data published by four devices in five. Under that threshold, a column compares empty fields.

ModelPriceSocket typeVA ratingWatt rating
APC Back-UPS BE425M$63NEMA, for a 120 V supply — implied throughout by the American market and never designated on the page. Every other unit on this shelf has NEMA outlets for a 120 V wall, except the Eaton 5S700G with IEC C13 at 230 V425 VA — stated in the first bullet and in the description. It is the figure on the box rather than the load the unit will carry255 W — stated in the first bullet alongside the VA figure, which puts the ratio at 0.60. This is the figure that bounds what can actually be plugged in
Tripp Lite AVR900U$150NEMA, for a 120 V supply — the description gives 120 V outright, which the Back-UPS listings on this shelf leave implied. Every other unit on this shelf has NEMA outlets for a 120 V wall, except the Eaton 5S700G with IEC C13 at 230 V900 VA — stated in the title and in the first bullet480 W — stated in the title and in the description, which puts the ratio at 0.53 — the lowest in this group, shared with the other Tripp Lite unit on this shelf. The watt figure bounds the load sooner than the VA figure suggests
APC Back-UPS BE900G3$164NEMA, for a 120 V supply — implied by the market and never designated on the page, plus USB-C and USB-A for charging. Every other unit on this shelf has NEMA outlets for a 120 V wall, except the Eaton 5S700G with IEC C13 at 230 V900 VA — stated in the title and in the first bullet. It is the figure on the box rather than the load the unit will carry540 W — stated in the title and in the first bullet alongside the VA figure, which puts the ratio at 0.60
Tripp Lite BC850RNC$175NEMA, for a 120 V supply — the description gives 120 V. Every other unit on this shelf has NEMA outlets for a 120 V wall, except the Eaton 5S700G with IEC C13 at 230 V850 VA — stated in the title and in the first bullet450 W — stated in the title and in the first bullet, which puts the ratio at 0.53
Eaton 5S700G$196IEC C13, at 230 V — stated in the title and in the first bullet, with the description giving an AC input range of 175 to 275 V at 46 to 70 Hz. American mains is nominally 120 V and an American wall socket is a NEMA pattern, so this is a European unit on an American shop and each device will need a C13 lead700 VA — stated in the title and in the first bullet420 W — stated in the title and in the first bullet, which puts the ratio at 0.60
APC Back-UPS Pro BX1350M$205NEMA, for a 120 V supply — the fourth bullet gives 120 V as the regulated output. Every other unit on this shelf has NEMA outlets for a 120 V wall, except the Eaton 5S700G with IEC C13 at 230 V1350 VA — stated in the title and in the first bullet810 W — stated in the title and in the first bullet, which puts the ratio at 0.60
APC Smart-UPS SMC1500-2UC$784NEMA 5-15R, designated — stated in the second bullet by pattern rather than described, which no other listing on this shelf does for an American socket. Every other unit on this shelf has NEMA outlets for a 120 V wall, except the Eaton 5S700G with IEC C13 at 230 V1500 VA — stated in the title and in the first bullet900 W — stated in the title and in the first bullet, which puts the ratio at 0.60

What each budget connects here

Lower range

$63 – $150

2 models

APC Back-UPS BE425M, Tripp Lite AVR900U

Mid range

$164 – $175

2 models

APC Back-UPS BE900G3, Tripp Lite BC850RNC

Upper range

$196 – $784

3 models

Eaton 5S700G, APC Back-UPS Pro BX1350M, APC Smart-UPS SMC1500-2UC

Where the numbers are read

Specifications: manufacturer sheets for network and storage gear and the matching Amazon product pages. Prices and availability: Keepa. Every figure in this table names its source.

Most recent revision in this category: October 26, 2026.

What we look at on UPS units

Every price named in a summary was read on the date that review carries. What a shop asks today is shown beside the product, and it moves.