GB vs GiB in cloud billing
By SightLab editors · 2026-08-22
Why 1000 versus 1024 quietly moves a cloud estimate, and which unit SightLab Cost uses.
A gigabyte (GB) is 1,000,000,000 bytes. A gibibyte (GiB) is 1,073,741,824 bytes. The gap is about 7.37%. Cloud consoles, operating systems, and invoices do not all use the same one, and the label on the screen is not always the unit on the bill.
If you take a 1 TiB disk that the OS reports as “1 TB” and multiply it by a GB list price, you understate usage. If you take a provider’s 1 TB internet tier as 1024 GiB, you overstate the free allowance.
What the major clouds document
AWS often measures storage and data transfer in GB where 1 GB = 10^9 bytes, while some instance memory figures are binary. Azure storage is typically decimal GB. Google Cloud storage is decimal GB; some compute memory pages still show GiB. Cloudflare R2 documents GB-month with a 10 GB-month free grant.
SightLab Cost calculators use decimal GB for storage and egress, and they say so under every result. Request prices are normalized to “per million operations” so you do not have to remember whether a SKU was per 1,000 or per 10,000.
A worked example
Suppose you serve 10,000,000,000,000 bytes in a month (10 TB decimal). At $0.09/GB that is $900. If you mistakenly treated the same byte count as 10 TiB = 10 × 1024 GiB ≈ 10,240 GB, you would estimate $921.60. The 7.4% gap is smaller than a wrong destination type, but it is large enough to fail a finance check.
Always match the calculator unit to the invoice unit. If your monitoring pipeline exports GiB, convert before you paste the number.
Related tools
- Cloud Data Egress Cost Calculator — Estimate monthly internet and cross-region data-transfer cost from a source region.
- Object Storage Cost Calculator — Break down storage, requests, retrieval, and egress for S3, Blob, GCS, and R2.