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Uninterruptible Power Supplies (UPSs) Price Comparison 2026

Compare 1,314 UPS units from APC, Eaton, CyberPower and more. Find the best price on uninterruptible power supplies for home, office and data centre use.

APC
Eaton
PowerWalker
CyberPower
Salicru
Vertiv
Infosec
Riello

Power cuts are rare in the UK — until they're not. A single unexpected outage can corrupt a database, crash a server mid-backup, or wipe hours of unsaved work. That's precisely why uninterruptible power supplies exist, and why the market spans everything from a compact desktop unit starting at 65 £ to enterprise-grade rack systems well beyond 1,493 £. We've analysed 1,314 products across this catalogue to help you cut through the noise.

APC dominates the conversation here — 280 products, a strong presence at every tier, and a brand that IT managers have trusted for decades. Eaton runs a close second with 250 products and a slightly lower average price point, making it the more accessible choice for SMBs. PowerWalker, often overlooked, offers genuinely competitive hardware at a fraction of the cost of the big two; their line-interactive and double-conversion models deserve more attention than they typically get. CyberPower rounds out the mainstream options with solid UK-specific models like the CP1600EPFCLCD-UK.

The topology question is where most buyers go wrong. Offline (standby) UPS units are cheap and fine for basic desktop protection, but their 4–6ms transfer time can cause sensitive equipment to reboot. Line-interactive models — the sweet spot for most offices — add automatic voltage regulation (AVR), which stabilises fluctuations without touching the battery at all. Online double-conversion units, like the PowerWalker VFI range, provide zero transfer time and the cleanest possible power output, but they run hotter and less efficiently. For anything housing a server or NAS, line-interactive is the minimum we'd recommend.

Connectivity matters more than many buyers realise. USB and serial ports handle local graceful-shutdown software, but if you're managing multiple units across a network, look for SmartConnect cloud monitoring (standard on APC's Smart-UPS C range) or a Network Management Card (NMC) slot. SNMP integration is essential for proper power distribution monitoring in any serious rack environment. And don't forget the long game: user-replaceable batteries (RBC) dramatically reduce the total cost of ownership — a sealed unit that needs returning to the manufacturer for a battery swap is a hidden expense that adds up fast. If you're also looking to extend runtime, check compatible UPS batteries and UPS battery cabinets for your chosen model before committing.

How to Choose the Right UPS: Topology, Capacity and the Details That Actually Matter

Most buyers focus on VA rating and price — and miss the three decisions that will actually determine whether their UPS protects them when it counts. The type of UPS, the runtime under real load, and the quality of the management interface matter far more than the headline wattage figure. Here's how to think through each one.

Topology: Offline, Line-Interactive or Online Double-Conversion?

This is the most important decision, and it's not just about price. Offline (standby) UPS units are the cheapest option — typically found below 177 £ — but they have a 4–6ms transfer time when mains power fails. Most modern ATX power supplies tolerate this, but sensitive industrial equipment, medical devices, and some older servers may reboot. If you're protecting a desktop PC or a home router, offline is fine. For anything more critical, it isn't.

Line-interactive UPS units add AVR (Automatic Voltage Regulation), which corrects voltage sags and surges without switching to battery at all. This is the right choice for the vast majority of office and SMB deployments — it extends battery life significantly and handles the minor fluctuations that are common on UK mains. The APC Smart-UPS and Eaton 5SC ranges sit firmly in this category.

Online double-conversion (like the PowerWalker VFI series) regenerates power entirely from the inverter, giving zero transfer time and the cleanest sine wave output. Essential for data centres and any load that cannot tolerate even a millisecond of interruption. The trade-off: efficiency drops to 85–90%, meaning higher running costs and more heat. Budget accordingly.

Capacity: Sizing Your VA Rating Correctly

The cardinal rule: never run a UPS above 80% of its rated capacity. A 1000VA unit should carry no more than 800VA of load. Under-sizing is the most common mistake — buyers pick a unit that matches their current load exactly, then add a monitor or a switch and wonder why the runtime collapses.

For a typical home office setup (desktop, monitor, router), 650–1000VA is usually sufficient. A small server or NAS with a couple of drives needs at least 1000–1500VA. A rack with multiple 1U servers, a switch, and a patch panel will likely require 2000–3000VA or more. The APC Smart-UPS SMT3000RMI2UC at 3000VA is a sensible ceiling for most SMB rack deployments. For larger installations, Eaton and Vertiv offer scalable solutions well into the enterprise tier.

Runtime Under Real Load — Not the Spec Sheet Figure

Manufacturers quote runtime at 50% or 25% load. At full load, expect roughly half the advertised figure. A unit claiming 10 minutes at full load will give you perhaps 5–6 minutes in practice under a heavy server draw. For most deployments, the goal isn't to keep running indefinitely — it's to allow a graceful shutdown of operating systems and databases before the battery dies.

If you need extended runtime (30 minutes or more), look for models that support external battery modules (EBM). The APC Back-UPS Pro External Battery Pack exists precisely for this purpose. Check compatibility before buying — not all UPS units support EBMs, and the cost of an external pack can rival the UPS itself.

Management Interface: USB, SmartConnect or NMC?

A UPS without a management interface is a black box. At minimum, you want USB connectivity and compatible shutdown software (PowerChute for APC, Intelligent Power Manager for Eaton) so that your server can initiate a graceful shutdown automatically when the battery drops below a threshold.

For networked environments, SmartConnect (APC's cloud portal, built into the Smart-UPS C range) or a Network Management Card (NMC) slot gives you remote monitoring, email alerts, and SNMP integration with your existing monitoring stack. The SMT1500RMI2UNC already includes an NMC — worth the premium if you're managing more than two or three units. Serial RS-232 is legacy but still found on some rack models for compatibility with older management software.

Form Factor: Tower vs Rackmount

Tower UPS units sit on or under a desk — straightforward for office use. Rackmount units (1U, 2U, 3U) slot into standard 19-inch server racks. Some models, like the APC Smart-UPS SMT1000RMI2UC, are rack-only; others ship as tower units with an optional rack conversion kit.

If you're building out a rack, go rackmount from the start — retrofitting a tower unit into a rack with an adapter is inelegant and wastes rack space. For a single server at a remote site or a branch office, a tower unit is often more practical. Check the depth of the unit against your rack before ordering; some 2U models are surprisingly deep.

User-Replaceable Battery (RBC) and Total Cost of Ownership

UPS batteries typically last 3–5 years. A unit with a user-replaceable battery (RBC) means you can swap it yourself in minutes for around £30–£80 depending on the model — no downtime, no courier, no service call. A sealed unit with an integrated battery that requires factory return is a false economy, especially for anything in a production environment.

APC's RBC programme is the most mature in the industry, with replacement cartridges widely available from Amazon, Currys, and specialist IT distributors. Eaton and PowerWalker also offer user-replaceable options across most of their range. If a unit doesn't clearly state RBC compatibility, treat it as a red flag for long-term ownership.

  • Entry-level protection (From 65 £ to 177 £) : Offline and basic line-interactive units for desktop PCs, home routers, and small NAS boxes. APC Back-UPS and Eaton 3S Mini dominate this tier. Expect 350–650VA, limited runtime (5–8 minutes at full load), and USB connectivity at best. Perfectly adequate for protecting a home office from brief outages — don't expect graceful server shutdowns or AVR.
  • The sweet spot for offices and SMBs (From 177 £ to 573 £) : Line-interactive units with AVR, 1000–2000VA capacity, and proper management interfaces. This is where the APC Smart-UPS C 1000VA and CyberPower CP1600EPFCLCD-UK live. You get SmartConnect or USB shutdown software, user-replaceable batteries, and enough runtime to safely shut down a small server. The right choice for most small business deployments.
  • Serious rack and server protection (From 573 £ to 1,493 £) : Rackmount 2U units from APC, Eaton, and PowerWalker at 1500–3000VA. NMC slots, SNMP support, and external battery module compatibility become standard. The PowerWalker VFI double-conversion range enters here, as does the Eaton 5PX. For IT managers running a proper server room, this is the minimum tier worth considering.
  • Enterprise and data centre grade (Over 1,493 £) : High-capacity online double-conversion systems from APC, Eaton, Vertiv, and Riello. Three-phase input, modular hot-swap batteries, and full SNMP/Modbus integration. Salicru and Infosec also appear at this level. These are not impulse purchases — they require proper load calculation, installation planning, and often a maintenance contract. Overkill for anything short of a dedicated server room or colocation environment.

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Frequently Asked Questions

What's the difference between a line-interactive and an online double-conversion UPS?

A line-interactive UPS uses AVR to correct voltage fluctuations and only switches to battery during a full power failure, with a transfer time under 4ms. An online double-conversion UPS runs all connected equipment through its inverter continuously, meaning zero transfer time and completely clean power output — but at the cost of lower efficiency (85–90%) and higher heat output. For most office and SMB use, line-interactive is the better practical choice. Online double-conversion is worth the premium only for servers or equipment that genuinely cannot tolerate any power interruption.

How do I calculate what VA rating I need?

Add up the wattage of everything you plan to connect, then divide by 0.8 to give yourself a 20% headroom buffer — that's your minimum VA requirement. Most desktop PCs draw 200–400W under load; a 1U server might pull 300–500W; a network switch typically 50–150W. A 1000VA unit (rated around 700W) comfortably handles a mid-range server plus a monitor and a switch. If in doubt, size up — running a UPS at 60–70% capacity rather than 80% extends both battery life and runtime.

How long will a UPS actually run during a power cut?

Expect 5–10 minutes at full load for most standard units — enough time for an automatic graceful shutdown, which is the real goal. Manufacturer runtime figures are typically quoted at 50% load, so halve them for a realistic estimate under heavy use. If you need 30 minutes or more, look for models that support external battery modules (EBM), such as the APC Back-UPS Pro range. Runtime drops sharply as load increases, so the single most effective way to extend it is to reduce what's connected.

Is a cheap offline UPS worth buying, or should I avoid them?

For basic desktop protection, an offline UPS is perfectly adequate — but know what you're getting. The 4–6ms transfer time is fine for a home PC or router, but it can cause sensitive equipment, older servers, or some NAS devices to reboot rather than ride through the outage. The bigger risk is buying a no-name offline unit with a poor battery and no management software. Stick to known brands (APC Back-UPS, Eaton 3S) even at the budget end — the battery quality and replacement availability alone justify the modest price difference.

Do I need a UPS with a Network Management Card (NMC)?

Only if you're managing multiple UPS units remotely or integrating with a monitoring platform like Nagios, PRTG, or Zabbix. For a single UPS protecting one server, USB with PowerChute or Intelligent Power Manager software is entirely sufficient. NMC becomes essential when you have several units across a network, need SNMP traps for alerting, or require centralised firmware updates. The APC SMT1500RMI2UNC ships with an NMC pre-installed — a genuine convenience, though you pay a significant premium for it.

How often should I replace the battery in my UPS?

Every 3–5 years under normal conditions, or sooner if the unit starts alarming or runtime drops noticeably. Heat is the main enemy of UPS batteries — a unit running in a warm server room will degrade faster than one in a climate-controlled environment. Most modern UPS units run a self-test cycle (often weekly) and will flag a failing battery via their management software. Don't ignore these warnings: a UPS with a degraded battery offers almost no protection and may fail silently during an actual outage.

What's the best UPS brand for a small business server room in 2026?

APC and Eaton are the two safest choices for SMB server room deployments, and the decision often comes down to budget and ecosystem. APC's Smart-UPS range has the widest replacement battery availability in the UK and the most mature SmartConnect cloud monitoring platform. Eaton's 5SC and 5PX lines offer comparable protection at a lower average price point, with excellent Intelligent Power Manager software. PowerWalker is worth serious consideration for double-conversion requirements on a tighter budget — their VFI IoT range delivers genuine online UPS performance at prices that undercut APC and Eaton meaningfully.