Does your photo library have enough frames for Instagram carousels? We counted: 502 images, 89 that qualify

When Postiada designs a post from an article it takes the photographs from the site’s own WordPress media library — the slides of a carousel never come from generated images, only the main frame may. That rule keeps the posts honest, and it raises a question every new site should ask before switching on social publishing: are there enough usable photographs in the library to feed a rotation for months? On 20 September 2026 we measured it for our two sites instead of guessing.

How did we measure the library?

WordPress exposes every image’s pixel dimensions through its REST API, so the whole count is one script, run from the browser while logged in to the site:

fetch('/wp-json/wp/v2/media?media_type=image&per_page=100&page=1')

The x-wp-total response header gives the total; each record’s media_details.width and height give the frame. Paging through the media endpoint returned 362 records for istambul.com (of 380 in the library, 358 with dimensions) and all 122 for istanbulhamam.com. Then each frame was tested against the minimum size of every box in our ten post layouts.

How many images clear each box?

Two things fall out of the table. The layout we had worried about most — the grid collage, which needs four photographs — is not the problem: 304 and 119 frames clear its small tiles, that is 85% and 97.5% of each library, and 87 and 29 clear the large one. The real bottleneck is the full-page box. Only 63 images on istambul.com and 26 on istanbulhamam.com are large enough to be a cover or a slide, and slides can only come from the library.

Is 26 frames enough?

It depends on how fast you burn through them. At three posts a week with half the rotation being carousels, a site publishes about 1.5 carousels a week, each with two library slides — roughly three slide photographs a week. Our no-repeat rule says a photograph may not be reused within eight weeks, so eight weeks of publishing needs about 24 distinct full-page frames.

istambul.com has 63, so it is comfortable. istanbulhamam.com has 26 against a need of 24 — about 8.6 weeks of supply, which sounds fine until two posts on the same subject land in the same fortnight and both want the same handful of interior shots. So we changed the rule for that site: its no-repeat window is now four weeks, which needs about 12 frames against a pool of 26. istambul.com stays at eight. The window is a per-site setting, not a global constant, precisely because libraries differ this much.

The trend is the right way round, at least. On 15 September istambul.com had 183 images, of which 31 cleared the full-page box; five days later the library had grown to 380 and the qualifying count to 63. Every article the engine publishes adds photographs, and a share of them are large enough to come back as slides.

Why are portrait frames the scarce resource?

The full-page box is 4:5 portrait, the tallest aspect ratio Meta’s publishing API accepts for a feed image (the content publishing documentation gives the allowed range as 4:5 to 1.91:1). Most library photographs are landscape. A landscape frame that clears the pixel threshold can still be used, but it is centre-cropped to 4:5 and loses roughly 40% of its width — and if there are people in the frame, a centre crop can cut through heads.

Hamam interiors — columns, domes, vertical light — survive the crop better than most subjects, which is one reason istanbulhamam.com gets away with a small pool. But the general lesson is that a landscape frame almost always looks better in a side box (grid tile, polaroid, comparison half) than forced into the full page. The next change to the frame selection follows from that: steer portrait frames to the full-page box and landscape frames to the side boxes, instead of cropping whichever frame comes first.

What should you check on your own site?

1. Count the full-page frames, not the library. A library of 400 images with 20 portrait frames is a small library for carousels. Run the script above and count frames at or above 1080×1350.
2. Work out your burn rate. Posts per week × share of carousels × slides per carousel gives slide photographs per week; multiply by the no-repeat window in weeks.
3. If supply is within about 10% of demand, shorten the window rather than accept repeats or lower the size threshold. A repeated photograph after four weeks is invisible to followers; a blurry upscaled slide is not.
4. Upload portrait originals. The cheapest fix by far. Photographers shoot verticals anyway; they are usually left out of the WordPress upload because articles use landscape covers.

We run this count for every site before Postiada goes live. During the preview week posts are designed but not published, so you see which layouts your library can feed before anything reaches your followers, and the rotation record tells you afterwards which layouts had to fall back and why. If the count comes back low, the answer is not a smaller rotation — it is a folder of vertical photographs.