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Disaster Recovery RPO Calculator

Derive the RPO your replication mode and backup interval actually deliver, the data at risk in the worst case, and the interval a target demands.

About Disaster Recovery RPO Calculator

The detection term is what most RPO calculations omit: your copy is only as good as the last point before the damage, so the minutes before anyone notices count against the objective just as much as the replication interval. That single term is why continuous replication does not automatically give a near-zero RPO against logical corruption, which propagates faithfully to the replica. RPO is where policy and physics diverge most often — nightly backups and a one-hour RPO appear together in real documents. This is an estimate from your own intervals and change rate; only a verified restore proves the recovery point.

Formulas

Disaster Recovery RPO

Achievable RPO = replication lag or interval + time to notice. Synchronous gives 0, asynchronous gives lag + detection, log shipping gives the shipping interval + detection, and backup-only gives the full backup interval + detection.

lagMinutes
Peak asynchronous replication lag converted to minutes
detect
Time before anyone notices and stops the damage spreading
backup interval
Worst case for backup-only protection is a whole interval of changes

Data at risk

Data at risk = change rate × achievable RPO; the interval a target demands = target RPO − detection time.

dataLossGb
Volume of change that would have to be re-entered or accepted as lost
requiredIntervalMinutes
Never larger than the target minus the time to notice

Worked example

With the default values below, Disaster Recovery RPO Calculator returns Achievable RPO of 10.8. Change any input above and every figure here is recalculated in your browser.

Inputs used

Data protection modeone of Synchronous replication, Asynchronous replication, Log shipping, Periodic backup only
Asynchronous replication
Backup intervalaccepts 0.25–720 hours
24 hours
Typical asynchronous replication lag at peakaccepts 0–86,400 seconds
45 seconds
Log shipping intervalaccepts 1–1,440 minutes
15 minutes
Data change rateaccepts 0–100,000 GB/hour
12 GB/hour
Time to notice the loss and stop writingaccepts 0–10,080 minutes
10 minutes
Target RPOaccepts 0–43,200 minutes
60 minutes
Restores verified from these copies in the last quarter
Yes

Results

Achievable RPO
10.8 minutes
Achievable RPO in Hours
0.179 hours
Data at Risk in the Worst Case
2.15 GB
Gap Against the Target
-49.3 minutes
Interval the Target Demands
50 minutes
Target Verdict
Target met — worst-case data loss sits inside the RPO
Protection Mode Note
Asynchronous replication is bounded by the replication lag, and lag grows under write bursts — size the RPO on the p99 lag, never the average
Verification Note
Restores verified this quarter — an RPO is only real once data has been recovered from the same copy chain

Step by step

  1. 1Values used
  2. 2Disaster Recovery RPO
  3. 3Data at risk
  4. 4Achievable RPO= 10.8 minutes
  5. 5Achievable RPO in Hours= 0.179 hours
  6. 6Data at Risk in the Worst Case= 2.15 GB
  7. 7Gap Against the Target= -49.3 minutes
  8. 8Interval the Target Demands= 50 minutes
  9. 9Target Verdict= Target met — worst-case data loss sits inside the RPO

Assumptions and limits

  • The result is derived only from the 8 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 3 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 Disaster Recovery RPO calculated?

Achievable RPO = replication lag or interval + time to notice. Synchronous gives 0, asynchronous gives lag + detection, log shipping gives the shipping interval + detection, and backup-only gives the full backup interval + detection. The detection term is what most RPO calculations omit: your copy is only as good as the last point before the damage, so the minutes before anyone notices count against the objective just as much as the replication interval. That single term is why continuous replication does not automatically give a near-zero RPO against logical corruption, which propagates faithfully to the replica.

Why does Disaster Recovery RPO matter?

RPO is where policy and physics diverge most often — nightly backups and a one-hour RPO appear together in real documents. This is an estimate from your own intervals and change rate; only a verified restore proves the recovery point.

What values do I need to enter?

This calculator takes 8 inputs: Data protection mode, Backup interval, Typical asynchronous replication lag at peak, Log shipping interval, Data change rate, Time to notice the loss and stop writing, Target RPO, Restores verified from these copies in the last quarter. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

Does synchronous replication give me a zero RPO?

Against infrastructure failure, effectively yes. Against ransomware or a bad deployment, no — the replica receives the corruption as faithfully as the good data, so the useful recovery point is your last clean copy. That is why an immutable, independent backup remains necessary alongside replication.

Should I use average or peak replication lag?

Peak, or better the p99. Lag matters precisely when write volume is highest, which is often when incidents happen, and a system averaging two seconds of lag can sit minutes behind during a batch window. Sizing on the average is the most common way an RPO is quietly missed.

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