ZIP to 7Z

How to Convert ZIP to 7Z Online

1. Upload Your ZIP File: Drag and drop or click "+ Add Files" to select one or more ZIP archives. Batch is supported — drop a dozen ZIPs at once.
2. Pick Combine Mode: Under "Combine?", choose Single Archive to extract every uploaded ZIP and repack the contents into one consolidated 7Z, or Individual Archives to produce a separate 7Z per uploaded ZIP. Defaults to Individual Archives when you upload archive files.
3. Review Defaults (Optional): xconvert applies LZMA2 with sensible defaults tuned for general-purpose use. Most users do not need to change anything; the defaults beat ZIP's DEFLATE on virtually every file type that compresses at all.
4. Convert and Download: Click "Convert". Files run through a server-side 7-Zip pipeline and the .7z is delivered for download — no sign-up, no watermark, no e-mail required.

Why Convert ZIP to 7Z?

ZIP has been the universal archive format since PKWARE published the spec in 1989 — every modern Windows, macOS, and Linux desktop opens it without extra software. That convenience comes at a cost: ZIP's standard compressor is DEFLATE (a Huffman-coded LZ77 variant from 1993), which trades efficiency for speed. The 7z format, introduced by Igor Pavlov in 1999 and used by 7-Zip since 2001, was designed from the start around LZMA — a global-dictionary algorithm that finds redundancy across the whole archive instead of small DEFLATE windows. LZMA2 has been the default 7-Zip codec since version 9.30 (October 2012) and adds proper multi-threading.

The practical result on real folders: 7z typically lands 30–70% smaller than the same content in ZIP, with the largest gains on text, source code, logs, CSVs, SQL dumps, and JSON. One published benchmark on a 1 GB mixed-media folder produced a 482 MB 7z versus a 695 MB ZIP — over 200 MB saved at the cost of slower compression. Convert your ZIPs to 7Z when:

• Long-term storage and backup — Cold storage, off-site backups, and tar-style "archive of archives" sit on disk for years; the one-time CPU cost of LZMA2 pays for itself in disk and S3 bills forever.
• Source code, logs, and build artefacts — Repetitive text content is exactly where LZMA's 4 GB dictionary shines; expect 40–60% size reductions over ZIP/DEFLATE for typical repos and log bundles.
• Stronger encryption than ZIP's defaults — 7z's only encryption is AES-256 with SHA-256 key derivation. ZIP's legacy "ZipCrypto" is broken; AES-256 ZIPs exist but interop is patchy across older tools.
• Encrypted file names — 7z can encrypt the filename list itself (header encryption), so an attacker can't see what's inside without the password. Standard ZIP exposes filenames even when contents are encrypted.
• Splitting huge archives — 7z natively splits into parts (.7z.001, .7z.002…) for upload caps on services like Discord (10 MB free), Gmail attachments (25 MB), or older FTP servers.
• Sharing with technical users — Developers, sysadmins, and power users universally have 7-Zip, Keka, p7zip, or The Unarchiver. For non-technical recipients on stock Windows or macOS, stay with ZIP.

ZIP vs 7Z — Format Comparison

Compression Method Quick Guide

Frequently Asked Questions

How much smaller will my 7Z be than my ZIP?

It depends on what's inside. For text, source code, logs, SQL dumps, or office documents (which are themselves DEFLATE-compressed XML), expect 30–50% smaller. For mixed folders with documents and modest images, 20–40%. For folders that are almost entirely already-compressed media (JPEG photos, MP4 videos, MP3 audio, FLAC), the savings collapse to single digits or even zero, because LZMA can't compress data that's already at the entropy limit.

Why is the conversion slower than just zipping the same files?

LZMA2 examines a much larger dictionary window — up to 4 GB versus DEFLATE's 32 KB — which is exactly what makes it find more redundancy and compress better. The price is CPU time. A real benchmark on a 1 GB mixed-media folder showed 7z taking 6 min 15 sec to compress versus 28 seconds for ZIP, but the resulting 7z was 213 MB smaller. For a one-time archival job that gets stored or transmitted many times, the trade is worth it.

Will the 7Z preserve filenames, folder structure, and timestamps from the original ZIP?

Yes. The conversion fully extracts the ZIP and repacks the contents into 7Z, preserving directory hierarchy, filenames (including Unicode), and modification timestamps. POSIX permissions and Windows ACLs from the original ZIP are not preserved — neither format guarantees those across platforms.

Will Windows or macOS open the 7Z natively?

Not yet, but the gap is closing. Windows 11 added native 7z read support in late 2023 (Insider builds) and shipped it in stable releases in 2024 — recent Windows 11 installs can extract .7z without third-party software. macOS Finder still cannot open 7z; users need Keka, The Unarchiver, or 7zX. Linux distros generally ship p7zip or have it in their package manager. For recipients on older Windows 10, macOS, iOS, or Android, share a ZIP instead or attach a one-line "install 7-Zip" note.

What's the difference between Single Archive and Individual Archives?

If you upload three ZIPs (reports.zip, invoices.zip, photos.zip) and choose Single Archive, the converter extracts all three and packs every file into one consolidated archive.7z — useful for delivering a single bundle. Individual Archives keeps the boundary: you get reports.7z, invoices.7z, photos.7z as separate downloads. The default for archive-to-archive conversion is Individual Archives, since you usually want to mirror the input.

Can I add a password during conversion?

The current ZIP-to-7Z flow uses default settings without a password. If your source ZIP was password-protected, you'll be prompted for the password to extract it; the output 7Z is unencrypted unless you re-encrypt locally afterwards with 7-Zip, Keka, or PeaZip. For maximum security on the resulting 7z, reapply AES-256 with header encryption (-mhe=on in the 7-Zip command line) so filenames are also hidden.

Is 7z's AES-256 actually stronger than a password-protected ZIP?

The cipher itself — AES-256 — is identical when both formats use it. The differences are in the key-derivation function (KDF) and what is encrypted. 7z uses SHA-256 with multiple iterations, making brute-force attacks slower. Many ZIP tools default to the legacy "ZipCrypto" cipher, which is broken (known-plaintext attacks recover keys in seconds); only WinZip-style AES-256 ZIPs are comparable. 7z also encrypts file headers (filenames and directory structure) when you enable that option — standard ZIP always leaks filenames.

What software opens .7z files on each platform?

7-Zip (Windows, the reference implementation), NanaZip (Windows 11, modernized fork), Keka and The Unarchiver (macOS), p7zip and Ark/File Roller (Linux), PeaZip (Windows/Linux, cross-format), iZip and Documents by Readdle (iOS), ZArchiver and RAR (Android), and WinRAR / WinZip on most desktops. Almost no built-in OS file manager on macOS, iOS, or Android opens 7z without one of these.

Should I convert to 7z or to tar.xz / tar.gz instead?

Same family: tar.xz uses LZMA2 (same codec as 7z) and matches 7z's compression ratio almost exactly — pick tar.xz if your recipient is on Linux/macOS where tar is universal but Windows-style 7z tools are not. tar.gz uses DEFLATE — same ratio as ZIP but Linux-friendlier metadata. Pick 7z when you want the strongest combination of compression, filename encryption, and Windows tooling.

Is the converted 7Z safe to use? Are uploads private?

Files run through xconvert's processing pipeline and are deleted after a short retention window (see the privacy policy on the homepage). For maximum privacy on sensitive archives, encrypt the source locally with 7-Zip first, then convert — the tool will pass the already-encrypted contents through unchanged. For very large archives (tens of GB), a local 7-Zip install will always be faster and bypass any upload bandwidth bottleneck.