What is a Gigabyte?

The gigabyte (GB) equals 1,000 megabytes (1,000,000,000 bytes decimal, or 1,073,741,824 bytes as GiB binary) and is the standard unit for smartphone storage, mobile data plans, and modern application sizes. Modern smartphones offer 64–1,024 GB of storage, mobile data plans range from 1 to 50+ GB per month, and operating-system installations typically require 20–80 GB. A 4K video stream consumes 6–8 GB per hour, and a typical app download is 50–500 MB to a few GB. The famous discrepancy between manufacturer-advertised capacity (GB decimal) and operating-system-displayed capacity (GiB binary) means a '1 TB' drive shows about 931 GB to the user. The gigabyte relates to the megabyte (1,000 MB = 1 GB), the terabyte (1,000 GB = 1 TB), the gibibyte (1 GiB = 1.074 GB), and the gigabit (1 GB = 8 Gbit).

Visual reference for how the gigabyte relates to other data units. Each row links to the full converter for that pair.

• Phone and device storage
• Mobile-data plan allowances
• Memory (RAM) sizes

• ✓SI: 1 GB = 1000 MB = 10⁹ B. Binary GiB = 2³⁰ B.
• ✓Hard drives use SI; OS may show binary — discrepancy ~7%.
• ✓Mobile data plans: SI GB.

• ✗Expecting 64 GB drive to hold 64 × 1,073,741,824 B — it's 64 × 10⁹ B (7% less by binary measure).
• ✗Confusing GB with Gb (gigabit, 1/8).
• ✗Mixing GB and GiB without noting the discrepancy.