Calculator inputs
Example data table
| Scenario | Source data | Daily change | Window | Recommended link | Initial sync link |
|---|---|---|---|---|---|
| Regional file services | 12 TB | 4% | 18 hours | 58.81 Mbps | 452.36 Mbps |
| Database replica | 4 TB | 9% | 12 hours | 222.14 Mbps | 746.31 Mbps |
| Large media archive | 55 TB | 2% | 20 hours | 161.22 Mbps | 1.78 Gbps |
These examples show how source size, change rate, and sync windows affect ongoing bandwidth and one-time initial synchronization demand.
Formula used
Raw changed data per day = Source data × (Daily change rate ÷ 100)
Effective payload per day = Raw changed data × (1 - Compression reduction) × (1 - Dedup reduction) × (1 + Protocol overhead)
Base bandwidth in Mbps = Effective payload per day × 8192 ÷ Replication window seconds
Recommended bandwidth = Base bandwidth × Peak burst multiplier × (1 + Safety headroom)
Initial sync bandwidth = Initial sync payload × 8192 ÷ Initial sync window seconds
The factor 8192 converts gigabytes into megabits. Compression and deduplication are treated as payload reductions. Overhead adds transport, metadata, encryption, and framing traffic back into the estimate.
How to use this calculator
- Enter the protected source data size and choose its unit.
- Add the percentage of data expected to change each day.
- Set the daily replication window and the interval between jobs.
- Estimate payload reduction from compression and deduplication.
- Add protocol overhead, burst multiplier, and safety headroom.
- Enter the available link speed to compare actual capacity.
- Set growth and planning months for a future bandwidth view.
- Submit the form to see the result block above the calculator.
Frequently asked questions
1. What does this calculator estimate?
It estimates steady-state replication bandwidth, initial sync throughput, payload per interval, future bandwidth after growth, and how much of your current link will be consumed.
2. Why is initial sync bandwidth higher?
Initial synchronization moves the full protected dataset, not just daily changes. Even with compression and deduplication, that first transfer usually demands far more throughput.
3. Should compression and deduplication always be used?
They help when data is repetitive or compressible. Encrypted, precompressed, and media-heavy workloads often see smaller reductions, so use realistic percentages from testing.
4. What is protocol overhead?
Protocol overhead includes headers, acknowledgments, encryption framing, retransmissions, and management traffic. It raises real link consumption above pure application payload size.
5. Why add safety headroom and a peak multiplier?
Real traffic is bursty. Headroom and peak factors protect against uneven change rates, retry storms, concurrent jobs, and temporary congestion during production hours.
6. How should I choose the daily change rate?
Use storage analytics, backup reports, or filesystem change tracking. If exact data is unavailable, model low, expected, and worst-case percentages before choosing a link tier.
7. Does low utilization always mean the link is safe?
Not always. Latency, packet loss, WAN quality, shared traffic, and appliance limits can still reduce real throughput below the calculated estimate.
8. Can this calculator help with disaster recovery planning?
Yes. It supports bandwidth sizing for cross-site replication, DR drills, migration rehearsals, storage failover, and cloud backup traffic planning across changing workloads.