File Size Calculator: convert file size instantly. Full formula, unit table, and worked example.
Decimal (SI, storage marketing): 1 KB = 1,000 B; 1 MB = 1,000 KB; 1 GB = 1,000 MB; 1 TB = 1,000 GB
Binary (IEC, OS reporting): 1 KiB = 1,024 B; 1 MiB = 1,024 KiB; 1 GiB = 1,024 MiB; 1 TiB = 1,024 GiB
Transfer time = File size / Transfer rate (match units — bits vs bytes: 1 byte = 8 bits)
Network speed is quoted in Mbps (megabits per second). Download time = file size (MB) / (speed Mbps / 8)