Database Size Estimation

TL;DR: Estimate storage requirements for PostgreSQL and MySQL databases based on schema and row count projections.

Estimating database size before deployment helps you choose the right instance size, plan storage costs, and set realistic retention policies.

Row size = sum of all column sizes + overhead. Each column type has a known size: INT (4 bytes), BIGINT (8 bytes), VARCHAR(n) (n bytes + 1-2 byte length prefix), TIMESTAMP (8 bytes), TEXT (variable + 1-4 byte pointer).

PostgreSQL overhead: Each row has 23-27 bytes of tuple header plus optional null bitmap (1 byte per 8 nullable columns). Each page is 8KB, and rows cannot span pages. Indexes add significant storage (B-tree indexes store a copy of the indexed columns plus a row pointer).

MySQL/InnoDB overhead: Each row has 5-6 bytes of record header. Variable-length columns use 1-2 byte length prefixes. Pages are 16KB by default. The InnoDB buffer pool must be sized to hold frequently accessed pages in memory.

Practical approach: Estimate your expected row count and average row size. Multiply to get data size. Add 50-100 percent for indexes. Add another 20-30 percent for overhead and fragmentation. This gives you a realistic total estimate.

Use the devvkit Database Size Estimator to get precise estimates for your schema.