Looking at the tables we used for recent benchmarking comparing Postgres vs. Timescale (https://blog.timescale.com/timescaledb-vs-6a696248104e):

PG 100M rows: 30.98GB (1 table)

TS 100M rows: 30.93GB (1 hypertable, 6 chunks)

Same results for the 1B table, just 10x larger (and TS has 10x more chunks).