File Size Converter
Convert between bytes, KB, MB, GB, and TB in decimal and binary units.
Click to copy · 1 KB = 1024 B (binary)
Why use it
File size conversion in seconds
Decimal and binary
Shows both KB/MB/GB (SI) and KiB/MiB/GiB (IEC) to eliminate confusion between manufacturers and operating systems.
Private
All calculations happen in your browser. No data sent, no history stored.
Practical cases
Calculate how many photos or videos fit, and estimate download times at your connection speed.
Instant
All units update in real time as you type.
How it works
Three steps, no hassle
Enter value and unit
Type the file size and select the unit: bytes, KB, MB, GB, or TB. You can also enter binary units (KiB, MiB, GiB).
See all conversions
The calculator shows equivalents in all units simultaneously, both decimal (SI) and binary (IEC).
Calculate practical cases
Find out how many photos, songs, or videos fit on a drive, or how long a download takes at your connection speed.
FAQ
Got questions?
It depends on the system. In the decimal (SI) system used by hard drive and SSD manufacturers: 1 KB = 1,000 bytes, 1 MB = 1,000,000 bytes, 1 GB = 1,000,000,000 bytes. In the binary (IEC 80000-13) system used by operating systems: 1 KiB = 1,024 bytes, 1 MiB = 1,048,576 bytes, 1 GiB = 1,073,741,824 bytes. This is why a '1 TB' drive shows ~931 GB in Windows: the manufacturer uses 10¹² bytes, but Windows divides by 2³⁰ (gibibytes).
It depends on format and camera. A 12 MP smartphone JPG weighs approximately 3–5 MB, so 1 GB holds about 200–330 photos. A 24 MP DSLR RAW file weighs 25–45 MB: 22–40 photos per GB. A WhatsApp-compressed JPG can be 200–500 KB: 2,000–5,000 per GB. Video: 1 minute of 1080p H.264 ≈ 150 MB (6–7 minutes per GB). 4K H.265: ≈ 400 MB/minute (2–3 minutes per GB).
Storage manufacturers (Western Digital, Seagate, Samsung) use the decimal system: 1 TB = 1,000,000,000,000 bytes. Operating systems traditionally used binary: 1 binary TB = 1,099,511,627,776 bytes. A 1 TB (decimal) drive divided by 2⁴⁰ = 0.909 TiB, which Windows reports as ~909 GB. macOS switched to decimal in OS X 10.6 Snow Leopard (2009) and now correctly reports 1 TB as 1 TB.
1 petabyte (PB) = 1,000 terabytes = 1,000,000 gigabytes. In concrete terms: stores roughly 20 million 4K photos, or 500 billion pages of text, or (estimated) all the music ever recorded in human history. Facebook stores over 100 petabytes of photos. Above petabyte: exabyte (1,000 PB), zettabyte (1,000 EB), yottabyte (1,000 ZB). The US Library of Congress text collection is approximately 10 TB — 0.01 PB.
Capitalization matters: MB (megabyte, capital B) = 8 Mb (megabit, lowercase b). Hard drives, files, and storage are measured in bytes (B). Internet and network speeds are measured in bits per second (bps, Kbps, Mbps, Gbps). A '100 Mbps' connection can download a 100 MB file in 8 seconds (100 MB × 8 bits/byte ÷ 100 Mbps = 8 s). This distinction is deliberate: ISPs prefer advertising in Mbps because the number appears 8× larger.
History of digital storage: from floppy disks to cloud-scale exabytes
The conflict between decimal and binary kilobytes has roots in the earliest days of computing. In 1956, the IBM 350 RAMAC hard drive stored 5 MB in a cabinet the size of two refrigerators. By 1980, the 5.25-inch floppy disk held 360 KB. The 3.5-inch high-density floppy, introduced in 1987, stored 1.44 MB — actually 1,474,560 bytes, a number that mixes systems: 80 tracks × 18 sectors × 2 sides × 512 bytes/sector. This historical inconsistency is the root of all the confusion that followed.
In 1998, the International Electrotechnical Commission (IEC) published IEC 80000-13, introducing binary prefixes: kibi (Ki, 2¹⁰), mebi (Mi, 2²⁰), gibi (Gi, 2³⁰), tebi (Ti, 2⁴⁰), pebi (Pi, 2⁵⁰). The goal was to eliminate ambiguity: KB always means 1,000 bytes, KiB always 1,024 bytes. Linux adopted IEC prefixes in kernel 2.6 (2003). macOS adopted them in Snow Leopard (2009). Windows, as of 2024, still displays 'GB' while calculating GiB.
Storage evolution over 65 years is staggering: floppy 1969 (80 KB) → hard drive 1980 (10 MB) → CD-ROM 1985 (650 MB) → DVD 1996 (4.7 GB) → hard drive 2000 (100 GB) → USB flash 2000 (8 MB, now up to 2 TB) → SSD 2007 (32 GB, now up to 100 TB) → cloud 2024 (petabytes per enterprise customer). Google, Amazon, and Microsoft operate data centers at exabyte scale (10¹⁸ bytes). The world is estimated to have generated over 120 zettabytes of data in 2023.