Compress Marketing Assets for Email, Ads and Social on Mac

One megabyte is the number to stay under. Mailchimp and Klaviyo both land on 1 MB per image. HubSpot gives no per-image figure; its editor estimates email size against Gmail’s 102 KB clipping threshold, and its Files tool takes 20 MB on free tools and 2 GB on paid accounts. A file that uploads cleanly in one platform can be refused or flagged in another.

Width is a judgment call, and the ranges differ by platform. Mailchimp’s legacy templates are 600 px wide and take images 600 to 1200 px wide; its new-builder templates are 660 px wide and take 660 to 1320 px. Klaviyo says 600 to 1000 px for a full-width image. Our recommendation, not a platform rule: export at twice the display width so the image stays sharp on a high-density phone, which is 1200 px for a 600 px column. That is about four times the pixels of a 600 px export, so the trade is sharpness against bytes. Under 1 MB, 1200 px is fine. If a file is over, drop to 1000 px for Klaviyo or 600 px before you touch quality.

Two traps sit under those figures. First, an ESP accepting a file is not the same as the file being a good idea: Klaviyo will take 10 MB and tells you to send 1. Second, Gmail clips long messages, and HubSpot’s estimate counts the HTML markup including links, formatting and images, and the page lists tracked links and pasted formatting among the things to trim. Compress the images, then check the estimate.

Photos are the usual offender, because a hero exported at full size from a design tool or a phone can pass the 1 MB line. Export it as a JPG at quality 75 and 1200 px wide, then read the output size in the batch results. If a file is above 1 MB, lower the width first, then the quality. Smol’s default quality is already 75, and how its defaults compare with ImageOptim’s lossless mode on 24 test photos is in the every-method comparison of Mac image compressors.

Send JPG, PNG and GIF. Use WebP and AVIF on the web page the email links to. The main offender is Outlook for Windows 2007 to 2019, but older Apple Mail and Windows Mail also fail on AVIF. The independent test database Can I email records support for each format, and its WebP and AVIF data files list every client and version.

Two caveats on that table. The test dates are old, so a newer Outlook build may behave differently, and Can I email lists Outlook for Windows only up to 2019. Still, a recipient on Outlook for Windows 2019 or earlier is in a client that does not support the format, so your hero may not show, and you would not see that in a current Mac inbox.

HubSpot’s Files tool accepts webp, and Klaviyo will convert a WebP upload to PNG for you. Accepting the upload says nothing about how the recipient’s client renders it. Export the email version as JPG or PNG yourself.

Video is a poor fit for an email body. With Gmail unable to play it, a safer pattern is a still frame or a short GIF that links to the hosted video. Smol does not make GIFs from video (its video outputs are MP4, MOV, WebM and MKV); see the last section for tools that do, and the GIF to MP4 guide for the reverse conversion and the GIF tools it names. If a video really must travel as an attachment, the limits and the arithmetic are in how to compress a video small enough to email, and the same for decks in getting a PDF under Gmail’s 25 MB limit.

Ad platforms publish their limits on spec pages. Organic limits are scattered and some are only documented for the publishing APIs that scheduling tools build on, so we have labeled which is which. The ad limits first. “No figure” means the page we read gave none. We read the Meta ad pages in English on 9 October 2026.

Keep ad images under 5 MB (aim for 4.5 MB or less) and they clear Google, LinkedIn and Meta. Google lists 5120 KB and LinkedIn lists 5 MB, so leave a margin. Meta’s limits differ by placement: the rows above are Facebook Feed ads with a traffic objective, and Reels and Stories ads have their own specs, which we did not read. For video, Meta recommends H.264 and LinkedIn lists H.264 or VP8, so export H.264 for ad uploads. Smol’s default video codec is H.265, so change it.

Instagram and TikTok publish their limits in their publishing API documentation, so those two rows are API limits, the kind a scheduling tool built on those APIs runs into, and we have no aspect-ratio or pixel figures for either. Uploading from the phone app may be looser. If a number matters, test the real upload.

Three limits are worth planning around. LinkedIn’s video spec for Pages and Career Pages drops QuickTime and MOV, and LinkedIn video ads take MP4 only. We found no LinkedIn page that states the rule for personal or company-page posts, so export MP4 for LinkedIn and the question goes away. Instagram Reels through the publishing API cap at 300 MB, which long or high-resolution footage passes easily. And the 5 MB image cap is the one a careless export trips. The first is a format problem, the other two are size problems. Smol converts MOV to MP4 and compresses to a quality setting (CRF) and a resolution, but it has no target-size control for video, so check each file’s result against the cap. For the MOV fix see converting MOV to MP4 on a Mac.

Small enough that the largest image on the page does not hold back Largest Contentful Paint. Google’s guidance is that a good LCP is 2.5 seconds or less at the 75th percentile, and on a campaign page the LCP element is often the hero photo.

The web is where the modern formats belong. On the 24 Kodak test photos on the benchmark page, Smol’s AVIF needed 22 to 26% fewer bytes than the best JPEG at the same SSIMULACRA2 quality score. Those test images are small, 768 × 512 film photographs, so treat the percentage as direction rather than a promise for a 2400 px hero. The same photos stored as PNG shrank by 69.2% at Smol’s defaults and by 92.1% when compressed to AVIF at quality 65 (all 24 images, 768 × 512). If your designers export photographic PNGs, that second number is the one to test on your own files.

AVIF belongs on the page and JPG in the email. Serve AVIF with a JPG fallback in a picture element; the markup, the width ladder and the layout-shift fixes are in image optimization for Core Web Vitals, measured, and the short version is on the compress images for web and AVIF converter pages. For UI screenshots with small text, look at the result at 100% before you ship it. PNG to WebP covers the lossless WebP route, which Smol does not offer because it always re-encodes.

Start from these and adjust after looking at the result. Quality is the 0 to 100 slider; the default is 75. At 75 and below Smol writes JPG output with 4:2:0 chroma, at 80 to 85 it moves to 4:2:2, and from 90 it writes 4:4:4, so a logo-heavy ad with colored text edges is the place to spend quality 85 or 90.

Three notes on that table. For video, the resolution list has fixed widths (original, 3840, 1920, 1280 and 854) and they act as bounding boxes, not exact widths; the screen recording guide measured a 3024 × 1964 capture coming out at 1662 × 1080 at the 1920 setting. We did not test a vertical clip, so treat that as a limit: Smol has no control we can vouch for that shrinks a 4K vertical clip to 1080 × 1920. Keep the original resolution, raise CRF to shrink the file, and check the first output before you run fifty. Why H.264 over H.265 for anything leaving your hands is in H.265 vs H.264.

For PDFs, the presets are long-edge pixel caps, not DPI targets, so effective resolution moves with page size. Medium caps the long edge at 1200 px with JPEG quality around 60, Large at 1800 px around 75. The preset explainer shows what that does to real pages. If a deck was exported from a slide tool, remember that the size is in the pictures; the same logic is worked through for slides in compressing slide decks on a Mac.

And metadata. Smol strips EXIF, GPS, IPTC and XMP from images by default. That removes the location from a photo taken at an event, which you want, and it also removes an embedded photographer credit or usage-rights note, which you might not. By default the output is a copy named _compressed next to the original, so keep the master with its credits in your DAM and publish the stripped copy. The privacy side is covered in stripping GPS from photos.

Sort by destination, not by file type. A folder per channel means every file in it gets the same settings, and the settings are the part people forget.

1. 1

   Keep the masters and work on copies

   By default Smol writes a copy next to the original with a _compressed suffix and does not overwrite the original, so your design exports stay intact for the next campaign.

2. 2

   Make one folder per channel

   For example email, ads, web and social-video. Drop the exports for each into its folder. Mixed file types are fine inside a folder.

3. 3

   Drop the folder on Smol and set the channel’s settings

   Drag a whole folder onto the window. Set output format, quality and the maximum size from the table in the previous section. For the email folder that is JPG, 75, 1200 px wide. For the video folder, switch the codec from the H.265 default to H.264.

4. 4

   Save the settings as a preset

   One preset per channel: Email, Ads, Web hero, Social video. Next campaign, pick the preset and the numbers are already right.

5. 5

   Run the batch and read the per-file results

   Smol shows progress and the saving per file. Files that cannot get smaller are kept as they were. Twenty-four small images take about seven seconds; video takes longer than images.

6. 6

   Spot-check before upload

   Open the biggest file, one with small text and the first vertical video at full size. Then upload from the copies.

The usual routes are in the table below, with what each does well.

The honest summary: if you compress a handful of public images a month, a free web tool or Preview is the right answer. The tool question changes when volume and sensitivity rise.

Sensitivity can matter more than file size. Product launches, embargoed announcements, unreleased packaging and client work under NDA can all pass through the compressor on the way to the CMS. An upload-based web compressor such as TinyPNG receives the file; Squoosh is the exception, as its page says images never leave your device. Whether that is acceptable is a call for your contracts and your legal team. Smol processes on your Mac and has no account and no server, so nothing is uploaded. That is a statement about where the processing happens, not a claim about any law or standard.

Speed is not Smol’s argument. A sips loop in the shell finishes 24 small images in under a second; Smol takes about seven. What you pay for is one window that takes images, PDFs and video together and applies saved settings.

Solo is $29 for one Mac. Team is $49 for three Macs, with seats managed from an admin dashboard, which fits a small in-house group. Enterprise is $20 per seat for 5 to 500 seats, managed from one dashboard. All of it is paid once with free updates, with no subscription and no per-file cap. There is no free trial, and purchases are not refundable, so read the last section first.

Consistency is the reason a team wants this. A preset is saved in the app on that Mac, so write the channel numbers into your asset guidelines next to the platform limits and recreate the presets from the workflow section on each Mac. A designer and a social manager then start from the same settings.

Two automation options fit a marketing day. The Finder Quick Action adds a compress item to the right-click menu, which suits the person who exports one image and wants it small now. A watched folder compresses whatever lands in it, which suits a folder fed by screenshots or camera exports. It has a known defect: it can make already-optimized files larger. Point it only at folders of fresh, unoptimized files, never at a folder of finished assets.

• Animated GIFs. Smol does not make GIFs from video, and in our test it could not convert an animated GIF to MP4. Compressing a GIF as a GIF is a poor trade: on our photographic test clip it saved 8.2% (both tests on Smol 1.0.34, 26 September 2026). Clop, at €15, converts video to GIF. The GIF to MP4 guide names other tools for GIF work.
• Logos and icons. Smol does not write SVG. A logo should be a vector from your brand kit. Smol can upscale a small raster 2×, 3× or 4×, but a 300 px logo is still better replaced than enlarged.
• Editing. It does not trim video, add captions or build the layout, and its fill resize mode crops to a box without letting you choose what is cut. Do that work in your design and video tools, then compress the export. Clop crops video if you want a lightweight cropper.
• An exact file size for video. There is no “make this 80 MB” control. Smol offers quality (CRF) and resolution. For a byte budget, use HandBrake’s average-bitrate mode. For images only, Neural mode takes a target from 4 to 4096 KB; it is a band, not a ceiling, and slow: about 28 seconds for one 768 × 512 image.
• Shrinking vertical video to a frame limit. LinkedIn video ads top out at 1080 × 1920 for 9:16. Smol’s resolution choices are fixed bounding boxes that we measured on a landscape recording only, so do not count on them to fit a 4K vertical clip. Use your editor or HandBrake, or keep the resolution and raise CRF.
• Teammates on Windows or Chromebooks. Smol is macOS only. Those people need another route.
• Pixel-identical output. Smol always re-encodes. If an asset must stay bit for bit the same, ImageOptim’s lossless mode is the answer.
• A few images a month. Preview, a free web tool for public files, or Clop at €15 will do. You do not need to spend $29.
• Pipelines that run on a server. A CMS or CDN that already serves resized AVIF needs no desktop step. For compression inside a build or an upload flow, look at the Smol API or an image library.

Slide decks have a limit too. Smol compresses the pictures before they go into a deck, the video before it is embedded, and the PDF export afterwards. It does not open a deck file and shrink it in place; the guide to compressing slide decks shows how to shrink one in PowerPoint itself.

For batches of finished video, the comparison of the tools is in batch compressing videos on a Mac, and the neighbors to this page are e-commerce product images and web agency image optimization, which share the landing page half of the work, and video production delivery for the video half.