🧮 Address Space by Bit Width

Assumes 1 byte (8 bits) per addressable unit.

Address Width	Formula	Bytes (exact)	Binary Capacity (IEC)	Decimal Capacity (SI)
16‑bit	$2^{16} × 1 \text{B}$	65 536 B	64 KiB	~65.5 KB
32‑bit	$2^{32} × 1 \text{B}$	4 294 967 296 B	4 GiB	~4.29 GB
64‑bit	$2^{64} × 1 \text{B}$	18 446 744 073 709 551 616 B	16 EiB	~18.45 EB

🔹 Notes

IEC (Binary) uses powers of 1024: KiB, MiB, GiB, TiB, PiB, EiB.
SI (Decimal) uses powers of 1000: KB, MB, GB, TB, PB, EB.
Why 16 vs 18:
- 16 EiB = 2^64 bytes in binary units.
- 18.45 EB = same byte count in decimal units.
To convert bytes → bits: multiply by 8. Example: 16 EiB × 8 = 128 Eib (exbibits).

Bytes_to_Bits  = Bytes × 8
KiB_to_KB      ≈ KiB × 1.024
Binary_to_Dec  ≈ Bytes × (1024^n / 1000^n)

Last updated on 2025-11-08