Formula
Bytes = Decimal GB × 1,000,000,000; GiB = Bytes ÷ 1,073,741,824Direct answer
A decimal gigabyte is 1,000,000,000 bytes. A gibibyte is 2³⁰ bytes, or 1,073,741,824 bytes. NIST documents both definitions and explains why a storage label in GB can display as a smaller number in GiB.
Variables and formula
- Decimal GB: the capacity printed with a decimal storage label.
- Bytes and GiB: equivalent counts using decimal and binary multipliers.
Bytes = Decimal GB × 1,000,000,000
GiB = Bytes / 1,073,741,824
Reproducible example
For a 500 GB drive, 500 × 1,000,000,000 = 500,000,000,000 bytes. Dividing by 1,073,741,824 gives about 465.66 GiB.
Interpretation
Neither display is inherently wrong; they use different multipliers. Check whether the device, operating system or specification says GB, GiB, TB or TiB before comparing capacities.
Assumptions and limitations
- The entered value is decimal GB.
- File-system overhead, reserved partitions and manufacturer formatting are not included.
- This calculator does not convert data-transfer speed.
Common mistakes
- Treating GB and GiB as interchangeable labels.
- Reading available file-system space as raw device capacity.
- Confusing bytes with bits.
Assumptions
- The input uses the decimal storage-label convention.
- Operating systems and manufacturers can choose different display conventions.
Sources and methodology
CalcMotive publishes the formula and assumptions so you can decide whether the estimate fits your use case. See our methodology standards.
- Definitions of the SI Units: The Binary Prefixes; National Institute of Standards and Technology; accessed Jul 27, 2026