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Backup Size & Storage Planner

Tell us what you need to protect and how far back you want to go. We'll work out the real size of a proper 3-2-1 backup with versions, the NAS and drives to hold it, what cloud storage would cost, and whether your internet connection can actually upload it, keep up each night and restore it in time.

What you're backing up

Versions and strategy

Your internet connection

Test my speed

Your backup plan

Can your connection cope?

    NAS and drives for the local copy

    SetupUsableRoom to grow

    Cloud storage options

    ServiceRough costGood to know

    Prices are rough guides for planning (they change, and vary by currency and contract). Check the provider before buying.

    Cloud sync platforms: will they cope?

    PlatformYour dataWorks well up toLimits and good practice

    Keeping sync fast and reliable

    • Sync only what people need. Use Files On-Demand (OneDrive), streaming (Google Drive) or selective sync (Dropbox) so files download only when opened. Each computer still tracks every synced item, so the total matters even when files aren't downloaded.
    • Aim for well under 100,000 synced files per person for snappy sync. Slow-downs commonly start there, well before the official limits.
    • Split big shares into several libraries or shared drives by team or year, and archive finished projects out of the synced area.
    • Keep folders reasonable: a few thousand items per folder at most, and keep paths short (OneDrive allows 400 characters, but many Windows apps fail beyond 260).
    • Don't sync databases, PST mailboxes, accounting data (Sage, QuickBooks Desktop) or virtual machines. They change constantly, get locked while open, and can be corrupted by sync. Back them up with proper backup software instead.
    • Plan the first upload: moving terabytes to the cloud takes days on most business lines. Migration tools (such as Microsoft's SharePoint Migration Tool or Migration Manager) are faster and more reliable than dragging files into a synced folder.
    • Sync isn't backup. Deletions and ransomware sync too. Protect Microsoft 365 or Google Workspace with a separate cloud-to-cloud backup.

    Sources: Microsoft's OneDrive and SharePoint restrictions and limitations, Google Workspace storage and upload limits, Dropbox and Box help centres, as checked in October 2026. Limits change, so check the provider if you're close to one.

    Where the space goes

    Part of the backupRestore pointsStored nowIn 3 years

      The 3-2-1 rule

      • 3 copies of your data: the original plus two backups.
      • 2 different types of storage, such as a NAS and the cloud, so one fault or failure can't take out both.
      • 1 copy offsite, safe from fire, flood and theft.
      • 3-2-1-1-0 adds 1 immutable or offline copy that ransomware can't encrypt or delete (cloud object lock, or a drive kept unplugged), and 0 errors: restores are tested regularly.

      Sync isn't backup

      • OneDrive, Dropbox and Google Drive copy deletions and ransomware encryption to every device. Their version history helps, but it's limited and easy to lose.
      • Microsoft 365 and Google Workspace data (email, OneDrive, SharePoint, Teams) needs its own cloud-to-cloud backup: Microsoft and Google keep their service running, but restoring your data after a mistake or attack is your job.
      • A RAID NAS isn't a backup on its own either: it survives a failed drive, not deletion, ransomware, theft or fire.
      • Test a restore at least every quarter. A backup you've never restored from is only a hope.

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