Replication Time Calculator
Estimate how long data replication will take given dataset size, link bandwidth, and compression ratio.
Inputs
e.g. 2 means the data is halved in size before transfer; 1 means no compression
Estimated Replication Time
2.28hrs
Estimated Replication Time
136.5min
Effective Data After Compression
100.00GB
Link Bandwidth
12.50MB/s
Step by step
Values used
Data Size to Replicate = 200 GB; Link Bandwidth = 100 Mbps; Compression Ratio = 2
Replication time
time = data_GB / (bandwidth_Mbps / 8) / compression_ratio
Estimated Replication Time
= 2.28 hrs
Estimated Replication Time
= 136.5 min
Effective Data After Compression
= 100.00 GB
Link Bandwidth
= 12.50 MB/s
How it works
Replication time is the effective data volume (after compression reduces what actually needs to cross the wire) divided by the available link bandwidth converted from bits to bytes. WAN links are quoted in Mbps (megabits/sec) while data is measured in GB (gigabytes), so bandwidth must be divided by 8 to get MB/s before the comparison is meaningful — a common source of 8x errors when sizing replication or DR links.
Formula
Replication time
time = data_GB / (bandwidth_Mbps / 8) / compression_ratio
Frequently Asked Questions
Why divide bandwidth by 8?
Network bandwidth is conventionally quoted in bits per second (Mbps) but data volumes are measured in bytes (GB), and there are 8 bits per byte — so a 100 Mbps link provides roughly 12.5 MB/s of usable throughput, not 100 MB/s.
Does this account for replication overhead like checksums or retries?
No — this models ideal sustained throughput at the stated compression ratio. Real replication also has protocol overhead, retransmissions on lossy links, and often runs below the link's rated bandwidth due to latency (especially over long-distance WAN links where TCP window size can bottleneck throughput before bandwidth is the limit).
How much does compression actually help for replication?
It depends heavily on data type — already-compressed data (video, encrypted volumes) may see a ratio near 1, while text, logs, or database dumps often compress 2-4x, directly cutting replication time by the same factor since less data crosses the link.