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Geo-Replication Calculator

Size cross-region replication bandwidth, storage and transfer cost from a daily change rate and compression.

About Geo-Replication Calculator

Replication traffic tracks the change rate, not the dataset size, so a 4 TB store that churns 4% a day ships about 160 GB before compression. Each additional replica multiplies both the storage bill and the egress, and the link only recovers from an outage using the capacity left above the steady change rate — which is why a link at 90% utilisation never catches up. Sizing a replication link on average throughput guarantees permanent lag during the daily write peak, and lag is the same thing as data loss when the primary region fails. Inter-region transfer prices differ per region pair, so confirm the current rate with your provider.

Formula

Geo-Replication

shipped per day = primary × daily change rate × (1 − compression); sustained Mbps = shipped × regions × 8,000 ÷ 86,400; catch-up = backlog ÷ (link capacity − sustained rate).

daily change rate
Share of the dataset rewritten each day, which is what replicates
compression
Reduction achieved on the replication stream, not on stored data
drain rate
Link capacity left over above the sustained change rate

Worked example

With the default values below, Geo-Replication Calculator returns Monthly Replication Cost of $448.80. Change any input above and every figure here is recalculated in your browser.

Inputs used

Primary datasetaccepts 0–100,000,000 GB
4,000 GB
Replica regionsaccepts 0–40 regions
3 regions
Data changed per dayaccepts 0–100 %
4 %
Compression achieved on the wireaccepts 0–90 %
40 %
Replica storage priceaccepts 0–10 USD/GB-month
0.023 USD/GB-month
Inter-region transfer priceaccepts 0–10 USD/GB
0.02 USD/GB
Replication link capacityaccepts 0.1–4,000,000 Mbps
500 Mbps
Change-rate peak factoraccepts 1–20 ×
3 ×
Replication outage to recover fromaccepts 0–43,200 minutes
60 minutes

Results

Monthly Replication Cost
$448.80
Replica Storage Charge
$276.00
Inter-Region Transfer Charge
$172.80
Data Shipped per Day
96.00 GB
Sustained Replication Bandwidth
26.67 Mbps
Link Utilisation at Peak
16.0%
Data Stored Across All Regions
16,000.00 GB
Catch-Up After the Outage
3.4 minutes

Step by step

  1. 1Values used
  2. 2Geo-Replication
  3. 3Monthly Replication Cost= 448.80
  4. 4Replica Storage Charge= 276.00
  5. 5Inter-Region Transfer Charge= 172.80
  6. 6Data Shipped per Day= 96.00 GB
  7. 7Sustained Replication Bandwidth= 26.67 Mbps
  8. 8Link Utilisation at Peak= 16.0

Assumptions and limits

  • The result is derived only from the 9 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Geo-Replication calculated?

shipped per day = primary × daily change rate × (1 − compression); sustained Mbps = shipped × regions × 8,000 ÷ 86,400; catch-up = backlog ÷ (link capacity − sustained rate). Replication traffic tracks the change rate, not the dataset size, so a 4 TB store that churns 4% a day ships about 160 GB before compression. Each additional replica multiplies both the storage bill and the egress, and the link only recovers from an outage using the capacity left above the steady change rate — which is why a link at 90% utilisation never catches up.

Why does Geo-Replication matter?

Sizing a replication link on average throughput guarantees permanent lag during the daily write peak, and lag is the same thing as data loss when the primary region fails. Inter-region transfer prices differ per region pair, so confirm the current rate with your provider.

What values do I need to enter?

This calculator takes 9 inputs: Primary dataset, Replica regions, Data changed per day, Compression achieved on the wire, Replica storage price, Inter-region transfer price, Replication link capacity, Change-rate peak factor, Replication outage to recover from. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

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