From 2 to 20 TB: Planning Your NAS Storage Right

Updated: 2026-04-29

Most NAS beginners make one of two mistakes: buy too little and hit full after a year, or buy way too much and pay for capacity they won't need for five years. Here's how to plan realistically and build a system that grows with you.

How Much Storage Do You Actually Need?

Smartphone photos: 15-30 GB per year. Family of four: 60-120 GB annually.

Movies (1080p): 5-15 GB each. 200 movies = 1-3 TB.

Movies (4K HDR remux): 40-80 GB each. 200 movies = 8-16 TB. This is where it gets real.

Music (FLAC): 10,000 songs: 300-500 GB.

Laptop backups: 1.5× actual data for version history.

For most households without a big 4K collection: 2-8 TB usable. More on Plex-specific planning here.

The Raw Capacity Trap

4×8 TB sounds like 32 TB. In RAID 5 you get 24 TB. In RAID 6 only 16 TB. Plus ~9% loss from TB-vs-TiB conversion. 32 TB raw becomes roughly 14.5 TiB usable in RAID 6. Less than half.

This is why running your drives through a RAID Calculator before buying is essential, not optional.

Price Reality 2026

HDD prices jumped significantly since late 2025, driven by hyperscaler demand.

8 TB: Seagate IronWolf ~$170-190, WD Red Plus ~$180-220. Previously $120-130.

16 TB: IronWolf Pro ~$350-400. Previously $250-300.

Sweet spot: 8-12 TB currently offers the best price per TB.

Set price alerts and buy on deals – more tips here.

How Many Drives to Start With?

Golden rule: Buy an enclosure with more bays than you need now. A 4-bay even if you start with 2-3 drives. Switching enclosures is expensive; adding drives is trivial.

Example: Ugreen DXP4800 Plus with two 8 TB drives. With Unraid or UGOS you get 8 TB usable plus parity. Add drive three after six months, four after a year. Always protected, investment spread over time.

Growing Without Data Loss

Unraid

Easiest. Plug in new drive at Unraid, assign in web UI, done.

Ugreen UGOS Pro

Supports RAID expansion with additional drives. Auto-rebuild.

SHR (Synology)

Replace drives with larger ones, capacity becomes available after rebuild.

ZFS / TrueNAS

More complex. Can't add drives to an existing vdev. Planning is essential with ZFS – the filesystem comparison helps with the decision.

Checklist Before Buying

1. Calculate your actual needs – what you have now plus 2-3 years of growth.

2. Choose your RAID level and calculate usable capacity.

3. Buy an enclosure with 1-2 spare bays.

4. Buy the drive size with the best price per TB – not the largest.

5. Plan your backup from day one.