Compressing Photos and Files for Real Estate Listings

There is no national standard, because there is no national MLS. Each one runs its own platform (Matrix, Flexmls, Paragon, Rapattoni, connectMLS) and each sets its own numbers. Here is what seven of them publish, quoted from their own documentation:

Read the first and last rows together. At RANW MLS a single photograph must be under 125 KB and 1280 × 960, and the platform silently downscales anything larger: “If an agent uploads a listing larger than 1280 x 960, the Paragon system will scale it down.” At SmartMLS the same photograph can be 40 MB.

Format rules are where received wisdom is wrong. Canopy MLS is genuinely JPEG-only: “Matrix only accepts images that are either .jpg or .jpeg. Other file types (even if they are built on the .jpg standard, such as .png) will not be accepted by the system.” CRMLS accepts ten formats including TIFF and PNG, despite a great deal of blog content insisting it is JPEG-only.

Two we deliberately left out. Bright MLS and Realtor.com publish their photo specs inside Salesforce single-page apps that return no article text to a fetch. The “20 MB” and “150 photos” figures circulating for Bright appear only on third-party blogs, which contradict each other within the same paragraph. Read Bright’s spec in a signed-in browser rather than trusting any page quoting a number, including this one.

Resize before you touch quality. This is the part most photo-editing advice gets backwards, and it matters more the tighter your MLS is.

A 24-megapixel frame off a full-frame body is around 6,000 × 4,000. Getting that under 125 KB on quality alone means dropping far enough to put visible blocking in the shadows of a dim interior, which is exactly where real estate photography lives. Resizing to the platform’s display size first removes roughly 95% of the pixels before the encoder sees them, and then quality 75 to 80 is comfortable.

Some MLSs do the resize for you. SmartMLS states that “Files that are other sizes will be resized automatically by the system” and converts GIF, BMP and TIFF to JPEG on the way in. That is a choice, not a default: you control neither the encoder nor the quality setting, and the result is what appears on every syndicated portal downstream.

One portal minimum worth knowing because it is published on both ends. Zillow documents that “Photo dimensions must be at least 330 pixels wide by 220 pixels high” and caps direct uploads at 50 MB, suggesting 1536 × 1152 and 10 MB for best quality (Zillow photo uploading tips). RANW MLS repeats the same 330 × 220 threshold in its own member documentation as the reason an over-shrunk photo vanishes from the Zillow feed. Redfin, by contrast, caps owner uploads at 20 images and publishes no numeric size or resolution spec at all.

For the mechanics on a Mac, see every method for compressing images on Mac and the compressor roundup. Keep MLS output as JPEG: AVIF and WebP are better formats and no MLS on this page accepts either.

Document caps are tighter than photo caps and almost nobody writes about them. Two verified examples pointing in different directions:

The ARMLS split is the detail that trips people up: a floor plan goes in as an image under the 15 MB media rule, while the HOA disclosure goes in as a document under the 10 MB PDF rule. Sending a floor-plan PDF through the document slot works; sending it through the photo slot requires converting it to JPG or PNG first, which is a conversion rather than a compression.

Stellar’s 15 MB reads as a shared budget rather than a per-file cap, and its handout confirms what fills it: “Many listing agents also attach items such as disclosures, condo/HOA documents, floor plans, surveys, etc.” A pile of scanned disclosures exhausts that fast.

Two things worth knowing about scanned supplements. Compression cannot add a text layer that was never there, so OCR before you compress if anyone needs to search the document later. And below roughly 82 PPI, body text stops being recoverable at all. We measured that collapse in compressing a scanned PDF without killing OCR; the portal-by-portal caps and the measured preset table are in when a PDF is too big to upload.

One trap specific to this workflow: macOS Preview’s Reduce File Size filter can make a text-heavy PDF substantially larger. On a 21-page text-only contract it produced a 111.8% increase. A disclosure packet is exactly that kind of file. The measurement and the reason are in how to compress a PDF on Mac.

Usually not, because most MLSs do not host video at all. They store a link, and the file lives with whoever you pay to host it.

ARMLS takes video as an embed: “Added as an embedded code. Most video hosting sites have an embed code in the ‘share’ option of the video.” Bright MLS says the same thing in policy form: “The MLS hosts only links to virtual tours, which are hosted by the Subscriber’s service provider” (policy dated 28 February 2024).

Which host you pick then becomes the rule, and some MLSs restrict that too. Doorify MLS, the Raleigh MLS formerly called Triangle MLS, refuses two of the obvious ones: “Please note that the MLS does not accept YouTube and Facebook virtual tours/videos due to the many live marketing links associated on the landing pages” (virtual tour requirements). It also bans live links out of the tour, including branded QR codes.

No MLS we read publishes a maximum video length. Every “keep it under three minutes” figure in circulation is a recommendation from a marketing blog, not a rule, and we are not going to repeat it as one.

Compression matters downstream of the MLS instead: the walkthrough going into an email, the clip for a social post, the file a client is watching on a phone. Measured on a public CC-BY test clip, our guide to compressing video on Mac took a 30,704,510-byte 1080p source to 6,111,954 bytes at default settings and 3,201,900 at web quality; reducing video file size explains the CRF control behind it.

Three honest cases.

Your photographer already delivers to spec. Most real estate photography businesses export a web-sized JPEG set alongside the full-resolution set precisely because MLS caps exist. If your delivery folder already holds 1,800 px JPEGs under 500 KB, you have nothing to do. Ask before building a workflow around a problem you do not have.

Your MLS resizes on upload anyway. SmartMLS resizes automatically and converts formats. If you are on a platform that does the work and you are not fussy about which encoder makes the decision, dragging originals in is a legitimate choice.

You need one photo fixed right now. Preview does it free: open the file, Tools → Adjust Size, then File → Export with the quality slider. It is already on the Mac and it is perfectly good for a single image.

Where a local app earns its keep on listing work: a shoot arrives as 60 files, every one needs the same resize and the same quality, and you want it done before the upload rather than during it. Smol is $29 once, takes a whole folder, writes JPEG at any quality from 0 to 100 with resize modes for fit, fill, width or height, and runs entirely on your Mac. Nothing goes to a web uploader, which matters if the folder also contains a floor plan with a client’s name on it.

One thing to be deliberate about: Smol’s image defaults strip metadata. For listing photos that is usually right, since camera serial numbers and GPS coordinates have no business in a public feed. It is the wrong default for a photographer archiving their own work, covered in image compression for photographers. The other vertical pages are web developers, podcasters and legal and HR teams. For the privacy side, see stripping GPS from photos.