Synology Storage Calculator

While hard drives may advertise large capacities, RAID configurations and redundancy significantly affect how much actual usable space remains. To avoid confusion and plan correctly, the Synology Storage Calculator helps you determine usable capacity, redundancy, and storage efficiency before buying or configuring drives.

Synology Storage Calculator

Note: For RAID 5, usable = (N-1)×size; RAID 6: (N-2)×size; RAID 10: (N/2)×size; RAID 1: size; SHR is similar to RAID 5/6 for identical drives. JBOD: sum of all drives.
Always check with Synology’s official calculator for mixed drives or advanced SHR!

A Synology Storage Calculator is an online tool designed to:

  • Estimate raw capacity (sum of all drives).
  • Calculate usable capacity after applying RAID.
  • Show redundancy levels (number of drives reserved for protection).
  • Display storage efficiency percentage.

It’s widely used by both home users and businesses to plan storage for backups, media, or enterprise workloads.

How the Synology Storage Calculator Works

The calculator works by taking three key inputs:

  1. Number of Drives – e.g., 2, 4, 6, or 8 HDDs/SSDs.
  2. Drive Capacity – e.g., 2TB, 4TB, 10TB.
  3. RAID Type – RAID 0, RAID 1, RAID 5, RAID 6, RAID 10, or SHR.

Based on these values, the tool applies standard RAID formulas to provide:

  • Raw Capacity: Number of drives × Drive size.
  • Usable Capacity: Available space after redundancy.
  • Redundancy Loss: Space reserved for protection.
  • Efficiency: Usable ÷ Raw × 100%.

Storage Calculation Formulas

Here are the main RAID calculations the Synology Storage Calculator uses:

  1. RAID 0 (Striping):
    Usable = n × Drive Size
    Redundancy = 0
  2. RAID 1 (Mirroring):
    Usable = Drive Size
    Redundancy = 50%
  3. RAID 5:
    Usable = (n – 1) × Drive Size
    (1 drive used for parity)
  4. RAID 6:
    Usable = (n – 2) × Drive Size
    (2 drives used for parity)
  5. RAID 10:
    Usable = (n ÷ 2) × Drive Size
    Half drives mirror, half provide performance.
  6. SHR (Synology Hybrid RAID):
    Usable = Total – Largest Drive (for 1-drive redundancy)
    (Flexible for mixed drive sizes).

Example Storage Calculations

Example 1: RAID 5 with 4 Drives (4TB each)

  • Raw Capacity = 4 × 4TB = 16TB
  • Usable Capacity = (4 – 1) × 4TB = 12TB
  • Redundancy = 1 drive (4TB)

Example 2: RAID 6 with 6 Drives (6TB each)

  • Raw Capacity = 6 × 6TB = 36TB
  • Usable Capacity = (6 – 2) × 6TB = 24TB
  • Redundancy = 2 drives (12TB)

Example 3: RAID 10 with 8 Drives (2TB each)

  • Raw Capacity = 8 × 2TB = 16TB
  • Usable Capacity = (8 ÷ 2) × 2TB = 8TB
  • Redundancy = 50%

Example 4: SHR with Mixed Drives (2 × 6TB + 2 × 4TB)

  • Raw Capacity = 6 + 6 + 4 + 4 = 20TB
  • Usable Capacity = 20TB – 6TB = 14TB
  • Redundancy = 6TB reserved

Benefits of Using a Synology Storage Calculator

  • Accurate Planning: Avoids guesswork when setting up NAS.
  • Budgeting: Helps determine how many drives to buy.
  • Flexibility: Compares different RAID options side by side.
  • Efficiency Tracking: See how much capacity is lost to redundancy.
  • Data Protection Awareness: Helps balance storage vs. safety.

Real-Life Applications

  • Home Users: Estimate space for movies, photos, and backups.
  • Small Businesses: Plan storage for file servers or surveillance systems.
  • IT Teams: Design enterprise storage with redundancy and performance.
  • Mixed Drive Setups: Use SHR for flexible capacity planning.

20 Frequently Asked Questions (FAQs)

1. What is a Synology Storage Calculator?
It’s a tool that estimates usable NAS storage after RAID.

2. Why do I need it?
To avoid overestimating capacity and ensure redundancy.

3. What’s the difference between raw and usable storage?
Raw = total drive size, usable = space left after RAID protection.

4. What is RAID 0 best for?
Maximum speed, but no data protection.

5. What is RAID 1 best for?
Mirroring for full redundancy.

6. Is RAID 5 safe enough?
Yes, but only 1 drive can fail safely.

7. What is RAID 6 used for?
Extra protection (2 drives can fail).

8. What is RAID 10 good for?
High performance and redundancy.

9. What is SHR?
Synology Hybrid RAID, supports different drive sizes.

10. Can I mix drive sizes in RAID?
Only with SHR, traditional RAID works best with identical drives.

11. How do I calculate efficiency?
Efficiency = (Usable ÷ Raw) × 100%.

12. Can I upgrade drives later?
Yes, Synology supports expansion and replacement.

13. What happens if a drive fails?
Depends on RAID level – redundancy allows recovery.

14. Is RAID a backup?
No, RAID improves availability but isn’t a substitute for backups.

15. Can I calculate SSD storage too?
Yes, the calculator works for SSDs as well.

16. What RAID is best for beginners?
SHR or RAID 5 for balance of space and safety.

17. Which RAID is best for business?
RAID 6 or RAID 10 for reliability.

18. Does RAID waste storage?
Not wasted – reserved for data protection.

19. Can I use the calculator before buying drives?
Yes, it helps you plan the right storage.

20. Is the Synology Storage Calculator free?
Yes, completely free and available online.

Final Thoughts

The Synology Storage Calculator makes NAS planning stress-free by showing exactly how much usable space you’ll get with different RAID setups. From home media centers to enterprise servers, this tool ensures you strike the right balance between capacity, cost, and redundancy.