How to Make a File as Small as Possible on Mac (Smallest File Size)

To make a file as small as possible on a Mac, first delete what you don't need, then compress with 7Z (LZMA2) at its maximum level as a solid archive. That combination usually beats ZIP by 5-15 percentage points on compressible content. Photos and video are the exception: they need re-encoding or resizing, because no archive format shrinks them by more than a few percent.

The rest of this guide walks through the steps in the order that actually matters, since the biggest gains come early and the last steps buy very little. If you already know your folder is mostly documents or code, skip to the format section. If it is mostly photos or video, read the media section first.

What is the fastest way to get the smallest possible file?

Work through five moves in order. Remove anything the recipient does not need, decide whether the content is compressible at all, reduce or convert media where that is acceptable, pick 7Z with LZMA2 at maximum with a solid block, and then stop once the size stops falling meaningfully.

The order matters because each step changes what the next one can do. Deleting a 2GB cache folder saves more than any setting ever will. Converting a folder of screen recordings can cut it in half, while switching from ZIP to 7Z on the same folder might save two percent. Archive settings are the last lever, not the first.

A quick way to check where you stand: look at the file types. Text, code, logs, CSV files, uncompressed images and disk images shrink a lot. JPEG, HEIC, MP4, MOV, MP3, and anything already zipped barely move. That single observation predicts most of the outcome, and our breakdown in how much space compression actually saves has the typical ranges by file type.

What should I remove before compressing anything?

The smallest bytes are the ones you never include. Before touching any compression setting, look through the folder for content that adds size without adding value for whoever will receive it.

Common offenders on a Mac include build folders and dependency directories such as node_modules, virtual environments, derived data from Xcode, and cache folders. Duplicate exports are another, like a project that holds both a full-resolution video and three re-exported copies. Hidden system files add a little clutter too, including .DS_Store files and the __MACOSX resource-fork folders that Finder's own ZIP tool tends to add.

Old versions are worth a look as well. Files named final, final2 and final-REAL often sit next to each other, and only one of them needs to travel. A five-minute cleanup regularly removes more than the whole rest of the process would.

Do this on a copy of the folder, not the original, so nothing valuable is lost by accident. If the goal is archival rather than sharing, keep the untouched original somewhere until you have confirmed the smaller version opens and contains everything.

Which format gives the smallest archive: 7Z or ZIP?

For general-purpose archives, 7Z with the LZMA2 algorithm gives the smallest result of the common formats. ZIP uses DEFLATE, an older method with a small search window, so it cannot find long-range repetition the way LZMA2 can. On plain text and logs, typical results run around 60-70% savings for ZIP and 75-85% for 7Z. Source code shows a similar gap, and office documents land around 25-40% for ZIP versus 35-50% for 7Z.

Those are directional ranges rather than measurements of a fixed test set, and your files will differ. The ordering is what holds up: 7Z ahead of RAR ahead of ZIP on compressible content, and all three converging on zero for already-compressed content.

ZIP still has a real advantage, which is that nearly every device opens it without extra software. If the recipient is a client on a locked-down work laptop, a slightly larger ZIP that opens on the first try can be the better choice. Our comparison of ZIP, RAR, and 7Z covers that tradeoff, and the 7Z versus ZIP for backups post looks at it from the storage side.

A quick note on availability in Unzipr: creating ZIP archives is free, including with an optional password, while creating 7Z archives and choosing compression levels is a PRO feature. Opening and extracting every format, 7Z included, is free.

Does maximum compression really make the file smaller?

Yes, but by less than most people expect. Maximum compression tells the algorithm to search harder for repeated patterns before deciding how to encode each block, which takes more time and memory in exchange for a smaller output. Going from a normal level to maximum typically adds a modest gain, often single digits up to the low teens in percentage points on compressible data, and close to nothing on media.

The cost is not small. LZMA2 at its highest settings uses a large dictionary, which means noticeably more RAM during compression, and it can take several times as long as a fast setting on multi-gigabyte input. Decompression stays comparatively quick and light, so the recipient does not pay the same price you do.

That asymmetry is exactly why maximum is a good fit for a file you compress once and open many times, such as a release archive or a long-term backup. It is a poor fit for something you regenerate daily. The fast versus maximum compression guide goes through that decision in detail, including how the gap changes with content type.

On a Mac with limited memory, a very large dictionary can push the system into swapping and slow everything down, which defeats the point. If compression starts to crawl, step down one level or close other heavy apps before you conclude the setting is broken.

What is a solid archive and why does it shrink files further?

A solid archive compresses all of its files as one continuous stream instead of compressing each file independently. That lets the algorithm notice that file 400 contains the same header, boilerplate, or repeated block as file 12 and reference it rather than store it again. For many small, similar files, the effect can be large.

The clearest wins come from folders of similar items. Think thousands of source files, exported log files, generated JSON, or a directory of near-identical text documents. Here, solid mode can noticeably beat the same 7Z settings without it, because the cross-file redundancy is exactly what it exploits. Mixed folders of unrelated large files gain far less.

The tradeoff shows up when you extract. To pull out one file from the middle of a solid block, the tool may have to decompress everything before it in that block. For a single-purpose archive that you will unpack whole, that does not matter. For a backup you intend to browse and grab single files from, it can make retrieval slower. Unzipr's free selective extraction helps in the ZIP case, where each file is stored independently.

So a practical rule: use solid for archives you will extract in full, and skip it if you expect frequent partial restores.

Why won't my photos and videos get any smaller?

Photos and videos are already compressed by their own formats. JPEG and HEIC apply lossy compression to the image itself, and H.264 or HEVC does the same for video. By the time an archive tool sees the file, the redundancy has already been removed, so results run roughly 0-4% for JPEG and 0-1% for MP4 regardless of format or level.

This is the most common reason people think their compressor is broken. The tool did its job, and there was simply nothing left to find. We explain the mechanics in why a compressed file stays the same size, and the same principle is why stacking an archive around a folder of MP4s gives essentially the same size back.

It also means that choosing 7Z, maximum compression, or solid mode will not rescue a media-heavy folder. Those settings can shave a few percent at best on such content. Any bigger reduction has to come from changing the media files themselves, which is a different operation with a different consequence.

How do I shrink photo and video folders themselves?

You re-encode or resize the media, which is lossy, and that is the real lever for photos and video. Archive compression is lossless and cannot do this. Re-encoding trades some quality for a much smaller file, so the question becomes how much quality you can afford to give up for the destination.

For photos, the options are lowering the pixel dimensions, raising JPEG compression a notch, or converting to a more efficient format such as HEIC, WebP or AVIF where the recipient can open it. Resizing a 12-megapixel photo to roughly screen size for sharing often shrinks it dramatically, since file size scales with pixel count. On a Mac, Preview can batch-resize and export a selection of images, and Photos can export at a chosen quality.

For video, the biggest options are reducing resolution, lowering the bitrate, or re-encoding with HEVC in place of an older codec. QuickTime Player's export menu offers smaller resolution presets, and dedicated encoders give finer control. Screen recordings, which contain long stretches of unchanging pixels, tend to shrink the most.

Be honest about the tradeoff. If the files are originals you will edit later or print, keep them untouched and compress a copy. If they are only going to be viewed on a phone or in an email, a smaller re-encoded copy is usually indistinguishable in practice. The article on compressing files without losing quality draws that lossless-versus-lossy line more carefully.

What is the step-by-step process for the smallest possible result?

Follow this sequence on a copy of your folder. It applies whether the goal is an email attachment, a cloud upload, or long-term storage, and it puts the highest-impact steps first so you can stop early when the size is good enough.

1. Delete caches, duplicates, old versions, and hidden system files the recipient does not need.
2. Sort the remaining files by type and note how much is media versus text, code, and documents.
3. For media you can afford to degrade, resize or re-encode it into a smaller copy and replace the originals in the folder.
4. Leave already-compressed files alone at the archive stage, since compressing them again adds time without reducing size.
5. Create a 7Z archive with LZMA2, the maximum level, and solid mode turned on.
6. If the recipient needs ZIP, build a ZIP instead and accept the size difference.
7. Extract the result into a scratch folder and confirm that everything opens and looks right before you delete anything.

Verification is the step people skip, and it is the one that prevents the worst outcome. A very small archive that turns out to be missing a folder is worse than a large one that works.

When should I stop trying to shrink it further?

Stop when the next step saves less than the time or convenience it costs. Compression follows sharply diminishing returns: the first cleanup and the switch to a good format capture most of the possible gain, while maximum level and solid mode chase the last few percentage points.

A useful test is to compare each attempt against the previous one. If maximum level saves 3% over normal on a 200MB archive, that is 6MB, which is rarely worth a long wait or a memory-heavy run. If the same 3% applied to a 50GB dataset that you will store for years, it is 1.5GB and worth the overnight job.

Also stop when you hit a hard floor. A folder that is 95% JPEG and MP4 has a floor set by those files, and no archive setting lowers it. At that point the only further options are lossy ones, and the decision is about quality rather than technique.

One more limit to keep in mind is receiving ability. A 7Z archive that the recipient cannot open saves them nothing. If you are unsure, send ZIP, or include a note about a free extractor. Our large file transfer settings guide covers the matching of settings to connection speed and file type.

Frequently asked questions

What is the smallest file size format on Mac? For general content, 7Z with LZMA2 at maximum compression and solid mode produces the smallest common archive, typically a further 5-15 percentage points below ZIP on compressible files. For photos and video, no archive format matters much, and only re-encoding or resizing the media reduces size significantly.

Can I compress a file to almost nothing? Only if it contains highly repetitive data, such as a huge log file full of repeated lines or a disk image with large empty regions. Photos, video, music, and files that are already compressed have little redundancy left, so they stay close to their original size.

Does compressing a ZIP file again make it smaller? Almost never. A ZIP's contents are already compressed, so a second pass finds almost nothing to remove and can even add a few bytes of overhead. If you want it smaller, extract the contents and recompress them using a stronger format like 7Z.

Will maximum compression damage my files? No. ZIP and 7Z compression are lossless, which means the extracted files are byte-for-byte identical to the originals at every level. Maximum only costs more time and memory during compression, not quality.

Is it better to compress each file separately or the whole folder? The whole folder, in most cases, especially with a solid 7Z archive, because the algorithm can find repetition across files. The exception is when you expect to extract single files frequently, since solid archives can be slower for partial restores.

Can I make a video smaller on Mac without an archive? Yes, and it is the effective route. Export a lower resolution or a more efficient codec such as HEVC using QuickTime Player or a video encoder. This is lossy, so keep the original if you may need full quality later.

The bottom line

The smallest possible file comes from cleaning out what you do not need, shrinking media at the source, and then using a solid 7Z archive at maximum level for whatever remains compressible, stopping when returns flatten. Unzipr creates ZIP archives for free, with optional password protection, and extracts every format for free, while 7Z compression with adjustable levels up to maximum is part of PRO.