How to Compress a TIFF on Mac (LZW, ZIP or Convert)

A TIFF is a container. Inside it the pixels can be stored raw, or squeezed with LZW, ZIP (Deflate), PackBits or JPEG. A huge TIFF is usually one that was saved with no compression at all. macOS ships two tools that can rewrite it without losing a pixel.

# LZW, lossless, built into macOS
tiffutil -lzw scan.tif -out scan_lzw.tif

# same thing with sips
sips -s format tiff -s formatOptions lzw scan.tif --out scan_lzw.tif

For ZIP (Deflate) compression, which macOS tools do not expose, use ImageMagick if you have it installed: magick scan.tif -compress Zip scan_zip.tif. Check the result with magick identify -format "%[compression]" scan_zip.tif.

Both LZW and ZIP are lossless. Open the new file next to the old one and nothing has changed except the size on disk. Check the size in Finder with Command-I.

It depends on the picture, so we measured two. Both are synthetic 4000 x 3000, 8-bit RGB images (36.00 MB uncompressed). One is smooth, with soft gradients like a graphic or a clean scan. The other carries heavy grain, which is what a high-ISO camera frame or a film scan looks like to a compressor.

The lesson is blunt. Lossless compression finds repetition, and grain has none. On the grainy file LZW saved about 9%, ZIP about 29%, and neither came close to JPEG. On the smooth file both cut the size to roughly a seventh. ZIP beat LZW on the grainy image and tied it on the smooth one, so use ZIP when you have the choice. Use LZW when the receiving software is old, because LZW is the more widely supported of the two.

These are synthetic images, so treat the percentages as a shape, not a promise. Run the command on one of your own files and look at the number.

Keep the TIFF when the file is a master. That means:

• You will edit it again, and each JPEG save would stack more loss.
• A printer, publisher or archive asked for TIFF specifically.
• It is 16-bit, has layers or has an alpha channel you need.

Convert to JPG when the TIFF is only being looked at: email, a web page, a client proof, an upload form. Our grainy test file went from 36.00 MB to 5.22 MB at sips quality 85, an 85% cut, and the same file in TIFF with the best lossless setting was still 25.72 MB. The full walk-through is in our guide to converting TIFF to JPG on Mac.

sips -s format jpeg -s formatOptions 85 scan.tif --out scan.jpg

One caution. The quality number is not portable between tools. In our test, sips at quality 75 wrote a 3.95 MB file from the grainy image while ImageMagick at 75 wrote 1.24 MB. Compare file sizes, not numbers, and judge the picture by eye at 100% zoom.

Raw size is width times height times channels times bytes per channel. Our 4000 x 3000 RGB image at 8 bits is 36 MB before any compression. A 16-bit file is double that. A scan at 600 dpi of a letter-size page is already well past 30 MP. If the TIFF will only be viewed on screen, the cheapest cut is fewer pixels:

sips -Z 2000 scan.tif --out scan_2000.tif

That halves each side and quarters the pixel count. The related questions are covered in why photo files are so large.

Smol is the wrong tool if you need a smaller TIFF that is still a TIFF. It has no lossless mode and always re-encodes, so it will not do LZW or ZIP rewrites. In our test today, compressing a TIFF with the output set to original produced a PNG, resized to fit inside 2000 x 2000 px by default. It went from 36.00 MB to 1.23 MB, but it is a different file type with fewer pixels. For a lossless TIFF, use tiffutil or sips, which are free. For pixel-identical optimization in general, ImageOptim is the honest answer, and our Smol vs ImageOptim comparison says where each wins.

Smol earns its $29 (once, one Mac, no subscription) when you have a folder of mixed TIFFs, PNGs and JPEGs headed for the web or email and want smaller JPG, WebP or AVIF copies in one drag, with originals left alone and nothing uploaded. Convert can also write TIFF from other formats. See pricing, or compare options in our best image compressor for Mac roundup.