Synology Calculator
Estimate your NAS storage capacity, redundancy, and RAID configuration efficiency.
Available Capacity
24.00 TBFormula: (N – 1) * Size
Storage Distribution Visualization
| Metric | Value | Description |
|---|
What is a Synology Calculator?
A Synology Calculator is a specialized tool designed for Network Attached Storage (NAS) enthusiasts and IT professionals to estimate the usable storage capacity of a Synology NAS system based on various RAID configurations. Since Synology devices support standard RAID levels as well as their proprietary Synology Hybrid RAID (SHR), calculating the actual space available after redundancy can be complex.
This Synology Calculator helps you plan your storage purchases by showing exactly how much space is dedicated to data protection versus how much is available for your files. Whether you are building a home media server or a high-availability business cluster, understanding these metrics is crucial.
Who Should Use It?
- Home Users: Planning a media library with redundancy.
- IT Managers: Estimating hardware costs for corporate backup solutions.
- Photographers/Videographers: Calculating the drives needed for long-term cold storage.
Common Misconceptions
A frequent error is assuming that a 10TB drive provides exactly 10TB of space. In reality, drive manufacturers use decimal measurements (10^12), while operating systems use binary measurements (2^40). Furthermore, RAID overhead and the Synology Calculator logic must account for the parity data required to keep your files safe if a drive fails.
Synology Calculator Formula and Mathematical Explanation
The mathematical logic behind the Synology Calculator varies depending on the RAID level selected. Below is the derivation for common configurations:
| Variable | Meaning | Unit | Typical Range |
|---|---|---|---|
| N | Number of Drives | Integer | 1 – 24 |
| S | Individual Drive Size | TB | 1 – 22 TB |
| C | Available Capacity | TB | Variable |
Calculations by RAID Level:
- RAID 0: C = N * S (No redundancy, maximum capacity).
- RAID 1: C = S (Mirroring, only works with 2+ drives, capacity of one drive).
- RAID 5: C = (N – 1) * S (One drive parity).
- RAID 6: C = (N – 2) * S (Two drive parity).
- RAID 10: C = (N / 2) * S (Mirrored pairs striped together).
- SHR: C = (N – 1) * S (Optimized parity for mixed drive sizes).
Practical Examples (Real-World Use Cases)
Example 1: The Small Business Server
Input: 4 Drives, 10TB Each, RAID 5.
Calculation: Using the Synology Calculator logic: (4 – 1) * 10TB = 30TB. One 10TB drive is reserved for parity. If any single drive fails, the data remains safe.
Example 2: The High-Security Vault
Input: 8 Drives, 8TB Each, RAID 6.
Calculation: (8 – 2) * 8TB = 48TB. Here, two 8TB drives (16TB total) are used for protection, allowing for two simultaneous drive failures without data loss.
How to Use This Synology Calculator
- Enter Drive Count: Input the number of physical drive bays you intend to fill in your NAS.
- Input Drive Size: Enter the capacity in TB of the drives. If using mixed sizes, use the smallest drive size for standard RAID levels or use the average for a rough SHR estimate.
- Select RAID Level: Choose from the dropdown menu based on your need for speed vs. security.
- Analyze Results: The Synology Calculator will instantly update the "Available Capacity" and show a visual breakdown of your storage.
- Copy Results: Use the copy button to save your configuration for a hardware purchase order.
Key Factors That Affect Synology Calculator Results
- Binary vs. Decimal: OS reporting (TiB) vs. Marketing (TB) causes a ~7-9% discrepancy in perceived space.
- File System Overhead: Btrfs or EXT4 file systems take a small portion of the "Available Capacity" for metadata.
- Synology Hybrid RAID (SHR): SHR allows for mixing drive sizes, which standard RAID 5 does not support efficiently.
- Hot Spares: If you designate a drive as a "Hot Spare," it must be subtracted from the total drive count in the Synology Calculator.
- System Partition: Synology DSM reserves a few gigabytes across all drives for the operating system.
- Fault Tolerance Requirements: Higher fault tolerance (RAID 6 or SHR-2) significantly reduces usable space but increases uptime safety.
Frequently Asked Questions (FAQ)
Q: Can I change RAID levels later?
A: Yes, Synology allows migrating from RAID 1 to RAID 5, or RAID 5 to RAID 6, but you cannot go "backwards" to a less redundant level without formatting.
Q: Is SHR better than RAID 5?
A: For most users, yes. The Synology Calculator shows that SHR provides similar capacity to RAID 5 but offers much more flexibility if you upgrade to larger drives later.
Q: What happens if I use different drive sizes in RAID 5?
A: In a standard RAID 5, the Synology Calculator logic would treat all drives as having the capacity of the smallest drive. SHR avoids this waste.
Q: How much space does the OS take?
A: Synology DSM typically uses about 4-8GB per drive for system partitions and swap space.
Q: Does the Synology Calculator account for SSD Caching?
A: No, SSD cache drives do not add to your storage capacity; they only improve read/write performance.
Q: Can I use 1 drive in RAID 5?
A: No, RAID 5 requires a minimum of 3 drives. Our Synology Calculator validates these constraints automatically.
Q: What is the maximum volume size?
A: Depending on the model and CPU (32-bit vs 64-bit), volumes are usually limited to 16TB, 108TB, or 200TB.
Q: Does RAID replace a backup?
A: Absolutely not. RAID protects against hardware failure, not accidental deletion, ransomware, or fire.
Related Tools and Internal Resources
- NAS Hardware Guide – How to choose the right Synology model for your bay count.
- RAID Comparison Table – A detailed look at speed vs protection across all levels.
- Storage Manager Tutorial – How to set up your pool after using the Synology Calculator.
- Btrfs vs EXT4 Guide – Choosing the right file system for your Synology NAS.
- Backup Strategy 3-2-1 – Why you need more than just a RAID setup.
- Drive Compatibility List – Ensuring your HDDs work with your Synology hardware.