A/B Testing Memory Requirement (Annual) Calculator
Estimate the annual data storage needed to retain A/B test event records based on traffic, event volume, record size, retention and replication.
Overview
This calculator estimates the annual storage needed for A/B testing event data. Enter your average test traffic, events recorded per visitor, average event size, retention period and replication level to estimate daily ingestion, yearly storage and peak retained capacity.
How it works
The calculator multiplies daily test visitors by tracked events per visitor to estimate daily event records. It then multiplies this by the average event size and converts the result to GiB. Annual storage is daily volume multiplied by 365 and by the replication factor. Peak retained storage uses your retention period instead of a full year. The variant count does not increase total events when the same visitors are split between variants; it shows the average traffic available to each variant.
How to use this calculator
- 1Enter the average number of visitors participating in A/B tests each day.
- 2Add the total number of control and treatment variants.
- 3Estimate how many tracked events each visitor generates per day.
- 4Enter the typical stored size of one event record in KB.
- 5Set your data retention period and storage replication factor.
- 6Review annual storage and peak retained capacity before adding platform overhead.
Example Calculation
Average daily test visitors
10000
Number of variants
2
Tracked events per visitor
10
Average event record size
2
Data retention period
365
Storage replication factor
2
Annual storage requirement
139.24 GiB
This setup creates about 0.19 GiB of raw event data per day and needs approximately 139.24 GiB of replicated storage for a full year of retained data.
Frequently asked questions
What counts as an A/B testing event record?
An event record can include a variant assignment or exposure, page view, click, conversion, revenue event or other behavior captured for experiment analysis.
Does adding more variants always increase storage?
Not necessarily. If the same total audience is divided among more variants and each visitor generates the same events, total event storage stays similar. More variants may add metadata or additional tracking events.
Why is a replication factor included?
Many storage systems keep more than one copy of data for availability and resilience. The replication factor estimates the capacity used by those copies.
Is annual storage the same as peak storage?
They are the same only when the retention period is 365 days. With shorter retention, peak retained storage is lower because older records are removed or archived.
What overhead should I add to this estimate?
Consider additional capacity for indexes, query acceleration, experiment metadata, backups, logs, data transformations and traffic growth. The amount varies by data platform and configuration.
Should I use KB or KiB for event size?
This calculator uses binary storage conversion, where 1 GiB equals 1,048,576 KB. For capacity planning, consistency with your storage provider's reporting convention matters more than the small unit difference.
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Assumptions and warnings
Assumptions
- Visitor volume and event activity are assumed to be consistent throughout the year.
- Each visitor is assumed to generate the same average number of stored events per day.
- The event size should reflect the stored size after any compression, serialization and field filtering.
- Replication is treated as a direct multiplier of storage use.
- This estimate excludes database indexes, metadata, backups, logs and infrastructure overhead.
Warnings
- Storage platforms can add significant overhead for indexes, partitions, backups and minimum allocation sizes.
- Actual capacity needs may be higher during traffic spikes, experiment launches or extended retention periods.