Mebibyte to Megabyte

MB (megabyte) = 1,000,000 bytes (SI decimal). MiB (mebibyte) = 1,048,576 bytes (IEC binary). MiB is 4.86% larger. This gap is why a file manager on Linux showing "512 MiB" of free RAM and a marketing sheet showing "512 MB" of RAM are technically different: the marketing sheet refers to fewer bytes.

The original CD-ROM standard defined capacity as 74 minutes of audio or 650,000,000 bytes. Technically this is 650 MB in SI terms, or approximately 620 MiB (since 650,000,000 ÷ 1,048,576 ≈ 620). However, the CD industry loosely used "MB" to mean 650 × 10⁶ bytes. Some media used 700 MB (≈ 668 MiB). This inconsistency is a classic example of the pre-IEC ambiguity.

Docker reports image sizes in decimal MB (e.g., "docker images" shows 150 MB), but the underlying layer storage on disk uses binary-aligned block sizes. A "150 MB" Docker image actually occupies roughly 143 MiB on disk before compression. Compressed layers further complicate things: a 150 MB uncompressed image might only transfer 50 MB over the network. Container registries like Docker Hub display compressed sizes, while "docker images" shows uncompressed — leading to frequent confusion in CI/CD pipeline size budgets.

One mebibyte (1,048,576 bytes) holds about: one minute of MP3 audio at 128 kbps (≈ 960 kB, so slightly under 1 MiB), a medium-resolution JPEG photo (0.5–2 MiB), about 200 pages of plain text, or the complete text of a short novel. A typical Linux kernel image at boot is 8–12 MiB compressed.

RAM chips are physically organized as binary address grids — each address line doubles the capacity, so sizes must be exact powers of 2 (4 GiB = 2³² bytes, 8 GiB = 2³³ bytes). USB flash drives use NAND flash that is also binary internally, but manufacturers reserve variable amounts for wear levelling, bad block management, and controller firmware. A "64 GB" USB drive might have 64 GiB of raw NAND but only expose 59.6 GiB (64 × 10⁹ ÷ 2³⁰) to the user — the label uses decimal marketing, unlike RAM which honestly reflects binary sizing.

A JPEG photo from a modern smartphone is typically 3–8 MB depending on resolution and compression settings. A RAW format photo from a DSLR or mirrorless camera is 20–50 MB per shot. A PNG screenshot at full HD (1920×1080) is about 1–3 MB; a compressed JPEG screenshot may be under 200 kB.

Video data usage depends heavily on quality: SD video uses roughly 700 MB per hour; HD (1080p) uses 1.5–3 GB per hour; 4K uses 7–20 GB per hour. These are byte-based measurements. In terms of bitrate: SD ≈ 1.5 Mbps, HD ≈ 5–8 Mbps, 4K ≈ 15–25 Mbps — where the "b" is bits, requiring division by 8 to convert to MB/s.

Compression algorithms like ZIP, GZIP, and ZSTD find and eliminate redundancy in data. Typical ratios vary dramatically by file type: plain text compresses to 20–30% of original size (a 10 MB log file becomes 2–3 MB); source code compresses to 25–35%; office documents (DOCX, XLSX) are already ZIP-compressed internally, so re-compressing gains little. JPEG, MP3, and H.264 video are already lossy-compressed and typically shrink by less than 5% with ZIP. A 100 MB folder of mixed files typically compresses to 40–60 MB. The key principle: compression removes statistical redundancy, so already-compressed or random data cannot be reduced further.

MB (megabyte) = 1,000,000 bytes (SI decimal). MiB (mebibyte) = 1,048,576 bytes (IEC binary). The difference is about 4.9%. Windows historically displayed storage in binary units but labelled them as "MB" — confusingly. Since Windows Vista, Microsoft has used the binary calculation consistently. macOS switched to SI decimal units in OS X 10.6 Snow Leopard (2009), matching the way hard drive manufacturers measure capacity.

Approximate data consumption per hour: web browsing = 60–100 MB, social media scrolling = 100–300 MB, music streaming (Spotify standard) = 40–50 MB, video calls (Zoom standard quality) = 300–500 MB, YouTube HD = 1,500–3,000 MB. These are rough averages and vary by content, settings, and network conditions.