Zip file type features and specifications, Deflate compression, maximum size, max number of files limit         

zip file extension

ZIP file format

zip file format
zip file extension




zip file type

ZIP is the default archive format for PeaZip free archiver, being a good, fast general purpose archiving format that can be handled by most archive managers - it is chosen as default format by most other file archivers for the same reason.
Optimized Deflate algorithm used in PeaZip improves ZIP format performances on modern multi core, multi threaded machines, and provides a slightly improved compression over classic Deflate implementation, and creates archives retaining full compatibility with ZIP standard.

zip file format specs

ZIP extension desingates a popular file archiving format, mainstream on Microsoft Windows systems.
ZIP format specifications are maintained by PKWare which originally developed the format as part of Phil Katz's compression utility PKZip (1989), and it is currently undergoing evaluation for ISO/IEC standardization.
Various file spanning schemes are employed by differnt utilities for creating split multi-volume zip archives, most popular is raw file spanning (as inplemented in 7-Zip, or Unix / Linux "split" command) and WinZip's custom spanning.
Newer archive formats like 7Z (7-Zip / p7zip), RAR (WinRar), and ACE (WinAce) have gained popularity and introduced several improvements (some of them later brought into ZIP format) like better compression ratio and better performances, recovery records, strong file encryption etc. - often at cost of inferior speed and higher memory requirements compared to faster, lightweight Deflate compression used in ZIp format.
Anyway, ZIP format retained much of its popularity earned in several years of widespread use due its ubiquitous support from many dedicated software alternatives to WinZip, as well as basic built-in support (extraction and often creation, i.e. Windows' "add to compressed folder" command) in most of modern operating systems, being .zip file format specifications released in public domain, which makes unzipping possible on almost all PC and devices.

zip extension

When is ZIP format recommended
Zip is a good choice anytime it is important to keep the archive compatible with most archive managers recipients may use, making it also an excellent choice for sharing and content distribution, being unzip generally possible on any platform. For same reson it is also recommended for long term archive / backup storage, as a such obiquitous format (with public domain specifications) is unlike to be unsupported in any conceivable scenario.
Also, ZIP is usually significantly faster than more powerful compression formats, both for archiving and for extraction steps.

zip file extension

Maximum number of files in a ZIP archive

ZIP format standard limits the number of files in archive to 2^16 (64 K files maximum), ZIP64 standard extension, supported by PeaZip, allows 2^32 files per archive (4 G files as maximum number)

Maximum total size of ZIP archive

A standard ZIP file can be up to 2^32 bytes in size (4 gigabyte of total size of the archive), ZIP64 standard allows the maximum archive size of 2^64 bytes (16 exabyte of total zip size), exceeding the current needs and limitation of most of current implementations of filesystems.
Please note some old zip archivers supports up to 2 GB for maximum archive size (and for max size of each input file), using a signed integer for representing the 32-bit wide size variable.

Maximum size of each file in a ZIP archive

ZIP format can accept input files up to 2^32 (4 GB) in size, while ZIP64 can archive files as large as 2^64 bytes in size (16 exabytes, each), far exceeding current needs and limits of common filesystems.

Zip format standard and variants (ZIPX, JAR, CAB, IPA, APK, COMPOUND...)

ZIP compression is quite fast and it's based on Deflate algorithm (like in GZip format, PEA format, and even in ZPAQ format at minimum compression level); alternatively Deflate64, BZip2, LZMA, and PPMd based compression is possible, and supported by PeaZip.

Recently WinZip (first GUI zip file utility on Microsoft Windows platform, and still one of most popular "zipper" program) introduced some new compression algorithms, and a new AES based encryption scheme, Advanced Encryption (AE-1, released in 2003, and AE-2 revision in 2004).
AE-encrypted archives as well as classic ZipCrypto-encrypted archives are supported by PeaZip (read and write), the application is also capable to read (decrypt) PKWare's AES encrypted zip archives, standard introduced in 2003 with PKZip 6.0 Professional Edition.

Since 2008 WinZip designed a new archival format, distinguished by ZIPX extension, supporting newer compression and encryption features, but ZIP format retained most of its popularity as common, "standard" way to pack and share data, as using a non-Deflate / Deflate64 compression algorithm may break compatibility with older zip utilities and use of a separate file extension was useful to avoid confusion for end users.

Many special-purpose variants were built on zip format structure (Android APK, Java JAR, Apple IPA, EPUB) or using Deflate compression (Microsoft CAB and MS Office OPC "Open Packaging Conventions" and COMPOUND file types).
For some of these file types PeaZip features a warning when trying to edit archive content (unless they are renamed as .zip files, and treated as plain archives), only browsing and extraction, because file format specifications involves to create / maintain special purpose meta-data fields which are out of the scope of a general-purpose file archiver - those files should be edited with specialized programs to correctly update required meta-data.

Read more: how to create, open, extract ZIP files with PeaZip free archiver

zip file format features

zip file format specifications

External online resources: ZIP file formatzip file format on Wikipedia, PKWare PKZipPKZip, Deflate algorithmzlib deflate specs




Phil Katz, 1989
ZIP: 64 K max number of files, 4 GB max size (archive, files)
ZIP64: 2^32 max number of files, 2^64 bytes max size (archive, files)

SPEED what are zip format features

Zip format features excellent speed either for zip and unzip operations. Deflate algorithm is light and fast for modern hardware, other supported compression algorithms are more resource demanding.

COMPRESSION RATIO zip archive type specs

Deflate algorithm is inferior to modern, more powerful (and power demanding) compressors as 7Z or RAR. Modern ZIP software supports additional algorithms to close the gap (BZip2, PPMd, LZMA) but archives may result unreadable for older utilities.

ADVANCED OPTIONS zip archive format specifications

Zip format features good advanced archiving options. Recent standard format revisions provide efficent encryption standards and allows archiving large files (over 4GB). Lacks recovery records option available for RAR format.

Synopsis: What is ZIP file extension. PKZip archives format. Zip file type features and specifications, functionalities in terms of speed, compression ratio, advanced options and encryption. Deflate compression characteristics. Maximum size, max number of files limit of Zip archive type.

Topics: ZIP file extension specs, zip format variants

PeaZip > FAQ > ZIP file format

zip archive extensionSUPPORTED ARCHIVE FORMATS

7Z file extension (7-Zip archive format)

BR file extension (Google Brotli compressed format)

BZ2 extension, BZip2 compressed file format

GZ extension, Gzip compressed file format

PAQ, LPAQ, ZPAQ file types

PEA file format specifications

RAR file extension (WinRar archive format)

What are TAR, TGZ, TBZ file types

WIM file extension, Microsoft Windows Imaging format

ZIP file extension

ZIPX file extension (WinZip archive format)

ZST file extension (Facebook Zstandard format)

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