A/B Testing Database Storage Calculator FAQ
Answers to common questions about A/B experiment event storage, assignment records, overhead, replication, and estimate accuracy.
Use these answers to understand what the storage calculator includes, how its inputs work, and where real database use may differ from the estimate.
General calculator questions
Basic questions about the scope of the estimate.
What does this calculator estimate?
It estimates database storage for A/B test visitor assignments and tracked event records during one experiment, including an overhead allowance and replica copies.
Is the result the size of one database?
No. The primary result is total provisioned storage across all copies represented by the replication factor.
Does it calculate storage cost?
No. It estimates capacity in GB. Pricing depends on the database service, storage class, region, and operational configuration.
Inputs and calculation logic
Questions about traffic, variants, events, and record sizes.
Should daily visitors be unique visitors?
Yes. Use the average number of unique visitors likely to enter the experiment each day when possible.
Why are visitor assignments included?
Assignment records link a visitor to an experiment and variant, and they may be needed for analysis, targeting, or auditability.
Do more variants require more storage?
Not automatically for a single experiment. Usually each visitor stores one selected variant assignment, although variant metadata or concurrent experiments can add data.
What counts as an event?
An event can be an exposure, page interaction, click, conversion, purchase, or another tracked action stored for analysis.
Accuracy and capacity planning
Questions about overhead, replication, and factors outside the estimate.
What should database storage overhead cover?
Use it for indexes, metadata, storage-engine structures, fragmentation, and operational headroom beyond raw record payloads.
Does replication multiply storage?
Yes. A replication factor of three represents three complete copies of the estimated data, including the primary copy.
Are backups included?
No. Backups, recovery copies, logs, exports, and warehouse storage should be planned separately.
How can I improve the estimate?
Measure representative stored records, observe index growth, test compression behavior, and compare the estimate with actual usage from a similar workload.
How is A/B testing database storage calculated?
The calculation estimates visitor assignments and event records, applies their average record sizes, then adds overhead and multiplies by the number of complete copies.
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