For most people: no. Microsoft Defender — the free antivirus already built into Windows — scores identically to Bitdefender and Kaspersky in independent AV-TEST evaluations, hitting 97–99% malware detection. The "free Windows antivirus is bad" advice is years out of date.
| Cost | When it's worth it | |
|---|---|---|
| Microsoft Defender | free, built in | low-risk users: normal browsing, official app sources, Windows updated |
| Malwarebytes Free | free | as a second-opinion scanner alongside Defender |
| Bitdefender Total Security | ~$20–40/yr promo, more at renewal | you want VPN, dark-web monitoring, parental controls, multi-platform, in one bill |
So who should still pay? Two groups. Power users and multi-platform households — Defender doesn't include a VPN, dark-web monitoring, parental controls or cloud backup, and if you want those bundled, a paid suite like Bitdefender is the tidy way to get them. Bitdefender also has the lowest system-performance impact of the paid options and consistently tops pure-protection rankings, so if you want a paid product, it's the one.
Malwarebytes is the odd one out — it's excellent as a supplementary on-demand scanner (run it when something feels off) but not really meant to be your only shield. The classic free setup is Defender always-on plus Malwarebytes Free for occasional deep scans.
The honest recommendation for a typical user in 2026: use Defender, add Malwarebytes Free if you want a second opinion, and don't pay for antivirus unless you specifically want the VPN/monitoring/parental-controls bundle — in which case Bitdefender is the pick.