Why there is no single 'best' antivirus
Search for the best antivirus software and you will find dozens of round-ups, each with a different winner. That is not because the reviewers are wrong. It is because 'best' depends on what you actually need: solid everyday protection at no cost, a family subscription covering several devices, extra scam and identity features, or something light enough not to slow down an older laptop.
Independent testers such as AV-TEST publish regular results for Windows security products, and editorial reviewers such as PCMag, Which? and TechRadar publish their own shortlists. Their winners change from year to year and sometimes disagree with each other. Treat any single ranking as a starting point, not a verdict. What matters is that the product you choose is actively maintained, comes from a reputable publisher, and is set up correctly on your machine.
This guide is written for UK home users and small businesses. It explains how to judge antivirus software for yourself, when the protection already built into Windows is genuinely enough, and when it is worth paying for more.
What to compare when choosing antivirus software
Ignore marketing badges and focus on a short list of practical questions.
- Detection and real-world protection. Look for products that appear consistently in independent lab tests over several months, not just one glowing review.
- Performance impact. Good antivirus should be barely noticeable during normal browsing, office work and video calls. Heavy scanning can make an older machine feel sluggish.
- False positives. Overly aggressive software can quarantine legitimate files or block installers you actually need.
- Price and device limits. UK subscriptions are usually sold per year for a set number of devices. Check the renewal price, not just the first-year offer, because renewals are often higher.
- Extra features. Password managers, VPN allowances, scam-call filtering and parental controls are common add-ons. Only pay for features you will genuinely use.
- Support and cancellation. Check how easy it is to cancel auto-renewal and get help in the UK. Consumer law gives you rights around auto-renewing subscriptions, but the process should still be straightforward.
- Reputation of the publisher. Avoid unknown brands, 'cracked' licences and anything pushed through a pop-up advert.
Is Microsoft Defender enough for most people?
For many Windows users, yes. Microsoft Defender, the antivirus built into Windows, is enabled by default, updates itself automatically and is regularly included in independent lab tests. It provides real-time protection against viruses and malware, plus web and phishing filtering in the Edge browser and on supported Windows versions.
Defender is a sensible baseline, especially if you:
- keep Windows and your apps updated;
- browse carefully and avoid pirated software;
- use a password manager and multi-factor authentication on important accounts;
- keep regular backups of your files.
Paid suites become more attractive if you want one subscription covering several devices and platforms, extra scam protection, a bundled VPN or password manager, or central management for a small business. They are not automatically more secure just because you paid for them.
One important caveat: Windows 10 reached the end of standard support on 14 October 2025. Microsoft offers Extended Security Updates (ESU) to eligible devices, but ESU eligibility is not the same as normal support, and it does not make an old PC equivalent to a new one. If you are still on Windows 10, plan an upgrade to a supported version of Windows rather than relying on antivirus alone.
How the major paid suites compare, in broad terms
Published reviewers tend to converge on a similar group of well-known products. PCMag, for example, has named Bitdefender Antivirus Plus and Norton AntiVirus Plus as Editors' Choice winners among antivirus utilities, while TechRadar's shortlist has featured Bitdefender Total Security, Norton 360 Deluxe, McAfee+ Premium, F-Secure Total and Avast One. Which? has tested Avast Free Antivirus, Avast One with Premium Security, AVG AntiVirus Free and Avira Internet Security, among others. AV-TEST publishes ongoing Windows results for products including Avast, AVG, Avira and Bitdefender.
Rather than declaring a winner, here is how the main options tend to differ in character:
- Bitdefender is frequently praised for strong protection with a light performance footprint.
- Norton (now part of the same group as Avast and AVG) bundles a broad feature set, including VPN and cloud backup in higher tiers.
- McAfee offers wide multi-device coverage and identity features in its premium plans.
- Avast and AVG have well-known free tiers and paid upgrades with extra features.
- F-Secure is a Finnish vendor often noted for straightforward, low-fuss protection.
These are examples drawn from published testers, not a recommendation to buy any particular product. Check current test results and prices before you commit, because both change frequently.
Free vs paid antivirus: what you actually give up
Free antivirus can provide genuine core protection. What you usually give up is not detection itself but the extras and the experience:
- Upsell prompts and occasional advertising for the paid version.
- Fewer or no bundled features such as VPN, password manager or parental controls.
- Limited or no technical support.
- Restrictions on commercial use, which matters if you run a business.
- Less central management across multiple devices.
If you only need baseline protection on one home PC and you are comfortable with Defender, paying for a suite is optional. If you want one subscription covering a household or a small team, a paid plan is usually simpler to manage.
Mac, iPhone and Android: what you actually need
Macs have built-in malware protection through XProtect and Gatekeeper, and Apple devices are generally well protected if you keep them updated and only install software from official sources. Third-party Mac antivirus can add value for scanning downloads or managing multiple machines, but it is not essential for every user.
On iPhone, you cannot install a traditional antivirus app because of how iOS is designed. Be sceptical of any app claiming to 'clean' your iPhone of viruses. What helps is keeping iOS updated, using strong passcodes, and being wary of phishing links and fake support calls.
Android is more open, so reputable mobile security apps can be useful, particularly for scam and phishing protection. Google Play Protect provides a baseline. Avoid sideloading apps from unknown sources.
Will antivirus slow my laptop down?
Modern antivirus is designed to have a light footprint during everyday use, but the impact varies by product and by hardware. On an older laptop with a mechanical hard drive and limited memory, any background scanning can be noticeable. If your PC already feels slow, it is worth addressing the underlying causes before blaming antivirus. Our guide to how to speed up a slow PC and laptop covers practical steps such as managing startup apps and freeing up disk space.
If you suspect antivirus is the culprit, check its scheduled scan times and exclude folders you know are safe, rather than disabling protection altogether.
Signs your PC may already be infected
Antivirus is prevention, not a cure for an existing problem. Warning signs include:
- Unexpected pop-ups, especially ones urging you to call a support number.
- A browser homepage or search engine that changes without your consent.
- New toolbars or extensions you did not install.
- Files being encrypted or renamed, or ransom notes appearing.
- Unusual network activity, or friends receiving messages from your account.
- Antivirus or Windows Update being disabled without your action.
If you see these signs, disconnect from the network, do not enter passwords on the affected machine, and back up important files to a separate drive before making changes. Our complete virus and malware removal guide walks through the cleanup process step by step. If ransomware is involved, stop and seek professional help rather than paying; our ransomware and phishing prevention guide explains how these attacks work and how to reduce the risk.
Setting up antivirus properly
Installation is usually straightforward, but a few habits make a real difference:
- Install from the official website or the Microsoft Store. Never install antivirus from a pop-up advert or a link in an unsolicited email.
- Run one real-time antivirus at a time. Running two can cause conflicts and slow your PC. Windows will normally disable Defender automatically when a third-party antivirus is active.
- Run a full scan after installation, then schedule regular scans at a time you are not using the machine.
- Turn on automatic updates so definitions stay current.
- Check browser protection and enable phishing and scam filtering if offered.
- Review auto-renewal settings so you are not surprised by a renewal charge.
- Keep backups. Antivirus cannot recover files that were never backed up. Our SSD vs HDD failure signs and backup strategy guide explains a sensible backup routine.
Be alert to fake antivirus pop-ups that claim your PC is infected and urge you to call a number or download a 'cleaner'. These are scams. Close the browser tab, do not call the number, and run a scan with your installed antivirus.
When to call a local London technician
Many people can install and configure antivirus themselves. It is reasonable to seek help if:
- You suspect an active infection and are unsure how to clean it safely.
- You need several devices or a small office set up with consistent protection.
- You want help choosing between free and paid options for your specific circumstances.
- Your PC is slow and you are not sure whether antivirus, hardware or something else is responsible.
- You are moving from Windows 10 to a supported version and want the transition handled carefully.
A local technician can install and configure protection, run a thorough scan, remove unwanted software and check that backups are in place. For broader PC issues, our Windows troubleshooting guide covers common errors step by step.
Whatever you choose, the fundamentals matter more than the brand: keep software updated, use strong unique passwords with multi-factor authentication, avoid pirated software and suspicious links, and keep regular backups. Antivirus is one layer of protection, not a substitute for sensible habits.