How to check PostgreSQL database size

pg_database_size reports the total disk space used by one PostgreSQL database. It is a logical PostgreSQL measurement: a provider's disk, storage, or billing number can also include write-ahead logs, system files, backups, retained history, or provisioned headroom.

The measurement matters because a current footprint is the starting point for capacity planning. Repeated observations made with the same query can reveal a growth trend; one observation cannot.

This read-only query returns raw bytes for calculations and a formatted value for display.

SELECT
  current_database() AS database_name,
  pg_database_size(current_database()) AS size_bytes,
  pg_size_pretty(pg_database_size(current_database())) AS size_pretty;

This bounded query separates table storage from attached indexes. It excludes PostgreSQL system and TOAST schemas from the ranked list, while pg_table_size still includes a table's own TOAST storage.

SELECT
  n.nspname AS schema_name,
  c.relname AS relation_name,
  CASE c.relkind
    WHEN 'r' THEN 'table'
    WHEN 'm' THEN 'materialized view'
  END AS relation_kind,
  pg_table_size(c.oid) AS table_bytes,
  pg_indexes_size(c.oid) AS index_bytes,
  pg_total_relation_size(c.oid) AS total_bytes
FROM pg_class AS c
JOIN pg_namespace AS n ON n.oid = c.relnamespace
WHERE c.relkind IN ('r', 'm')
  AND n.nspname NOT IN ('pg_catalog', 'information_schema')
  AND n.nspname !~ '^pg_toast'
ORDER BY total_bytes DESC
LIMIT 25;

• Connect to the exact database you intend to measure; current_database() confirms its name.
• Keep discovery queries read-only, bounded with LIMIT, and filtered away from system schemas.
• Store raw bytes and a capture timestamp if you want to calculate growth. Formatted strings are for display, not arithmetic.
• Compare observations made with the same query, database, units, and an understood time interval.
• Expect a busy database to change while the query runs; size calls are observations, not a transactionally frozen storage inventory.

The PostgreSQL health check can analyze a bounded snapshot of database, table, and index footprint. A connected database can collect supported size measurements over time, making direction and change more useful than a single number. DatabaseMeter reads statistics and catalog measurements; these size checks do not select application row contents.

Use the database growth calculator when you already have two dated byte observations and want a transparent pace and threshold projection.