Calculator Inputs
Plotly Graph
This graph compares recommended provisioned throughput against possible backup windows. After calculation, the selected point and current link capacity appear automatically.
Example Data Table
| Scenario | Protected Data | Backup Type | Window | Reduction | Recommended Link |
|---|---|---|---|---|---|
| Branch office nightly | 2 TB | Incremental at 6% | 4 hours | 1.6× compression, 1.2× dedupe | 98 Mbps |
| Core VM estate | 12 TB | Full | 8 hours | 1.8× compression, 1.4× dedupe | 4.16 Gbps |
| Database estate | 25 TB | Differential at 3% for 5 days | 6 hours | 1.3× compression, 1.1× dedupe | 1.34 Gbps |
| Archive replication | 60 TB | Custom 8 TB move | 10 hours | 2.2× compression, 1.8× dedupe | 630 Mbps |
Formula Used
The calculator converts logical backup scope into physical transfer load, then translates that load into link throughput inside the chosen window.
Logical Backup Scope = Protected Data × Scope Factor
Scope factor is 1.0 for full, change rate for incremental, and change rate × days since full for differential jobs.
Growth Adjusted Scope = Logical Backup Scope × (1 + Annual Growth) ^ (Planning Months / 12)
This projects the backup size forward so you can size links for future demand instead of only today.
Reduced Data = Growth Adjusted Scope / (Compression Ratio × Deduplication Ratio)
Compression and deduplication lower the amount of data crossing the network.
Transfer Payload = Reduced Data × (1 + Protocol Overhead + Encryption Overhead + Retry Allowance)
These factors account for framing, metadata, retransmissions, and extra encrypted traffic.
Required Throughput = (Transfer Payload × 8) / Backup Window Seconds
This gives the raw minimum line rate needed to finish within the selected backup window.
Recommended Provisioned Link = Required Throughput / Utilization Target
If you only want to run a link at 75%, the provisioned link must be larger than the raw requirement.
How to Use This Calculator
- Choose the backup type that matches your job design.
- Enter the protected data size, or enter a custom logical amount.
- For incremental or differential jobs, add the daily change rate.
- Set the backup window and the number of parallel streams.
- Enter compression, deduplication, protocol, encryption, and retry assumptions.
- Add growth and your current link speed for a practical fit analysis.
- Press the calculate button to view throughput, window fit, and provisioning guidance.
- Export the result to CSV or PDF when you need documentation.
FAQs
1. What does the calculator actually size?
It sizes the network throughput needed to move backup data within a defined time window after accounting for reduction, overhead, retries, and growth assumptions.
2. Why is the recommended link larger than required throughput?
The recommended link includes your utilization target. If you only want to use 70% to 80% of the link, the provisioned capacity must be higher.
3. When should I use differential instead of incremental?
Use differential when each job backs up all changes since the last full backup. Use incremental when each job backs up only new changes since the previous backup.
4. How should I estimate compression and deduplication?
Use measured values from your backup platform whenever possible. Databases, media files, and already compressed data often reduce less than general file shares.
5. Does this account for packet loss and retries?
Yes. The retry allowance field adds extra transfer volume so sizing reflects less than perfect network conditions or backup job restarts.
6. Can I use this for cloud backup planning?
Yes. It works for on-premises, WAN, and cloud backup links as long as your assumptions for overhead, window, reduction, and growth are realistic.
7. Why include annual growth in a bandwidth estimate?
Growth prevents undersizing. A link that works today can miss tomorrow’s backup window after protected data expands for several months.
8. What is a good utilization target?
Many teams choose 60% to 80% to leave room for bursts, contention, monitoring traffic, and recovery operations. The right target depends on your risk tolerance.