Data Type Sizes

System Design

A table of data type sizes in Postgres, useful for back-of-the-envelope calculations. The values will differ for different database systems, but the relative sizes will be similar. Squares are scaled in size logarithmically.

Type	Postgres Data Types	Size	Notes
Integer	`SMALLINT`: 2 bytes `INTEGER`: 4 bytes `BIGINT`: 8 bytes	2 bytes 4 bytes 8 bytes	Used for numeric fields, IDs, and counters. Larger sizes support larger ranges.
Floating Point	`REAL`: 4 bytes `DOUBLE PRECISION`: 8 bytes	4 bytes 8 bytes	Used for scientific calculations or approximate values.
Timestamp	`TIMESTAMP`: Without timezone `TIMESTAMPTZ`: With timezone	8 bytes	Used for date and time fields, with or without timezone information.
UUID	`UUID`: 16 bytes	16 bytes	Universally unique identifiers for distributed systems.
Enum	`ENUM`: 1-4 bytes	1 byte 4 bytes	Represents a predefined set of values. Examples: User roles, statuses, or category lists.
String	`VARCHAR(n)`: Up to `n` characters `TEXT`: Unlimited length	~100 bytes ~1 KB ~10 KB	Short: Usernames, titles, or short sentences. Medium: Descriptions or paragraphs of text. Long: Articles, blog posts, or large text fields.
JSONB	`JSONB`: Variable length	~100 bytes ~1 KB ~10 KB	Small: Simple JSON objects. Medium: Nested JSON or API responses. Large: Complex JSON with many fields.
BYTEA	`BYTEA`: Variable length	~1 KB ~100 KB ~1 MB	Small: Icons or thumbnails. Medium: Profile pictures or compressed files. Large: High-resolution images or large documents.
Legend: 1 byte 100 bytes 1 KB (1,024 bytes) 10 KB 100 KB 1 MB (1,048,576 bytes)