How to make a seamless carousel

What makes a carousel seamless?

The idea is simple. Instead of making four separate slides, you make one image and let the swipe reveal it in slices. A skyline, a table, a long headline or a path continues across the cut, so the next panel feels like the same picture sliding in.

A printed gatefold works the same way: one artwork that spans a folded sheet (Wikipedia: Gatefold). The only difference is that your fold lines are invisible and live between panels.

How many panels should a seamless carousel have?

Three to six panels suit most posts. Two panels make a short reveal, and past six the viewer has to commit to a long swipe before the picture pays off. The social app allows up to 20 slides, but a limit is not a target.

Your source photo often settles the number for you. Divide the photo's width by its height, multiply by the panel height in panel widths (1.25 for 4:5, 1.33 for 3:4, 1 for a square), and round. A 6000 x 2400 px photo has a 2.5 ratio, so at 4:5 it fills 2.5 x 1.25, about 3 panels. Seamfold uses this same arithmetic when you pick a single wide photo, then caps the result at the limit of your plan.

How do you make one, step by step?

Seamfold is built around exactly this loop. You edit one spread with dashed fold lines, and it saves the panels to Photos in order. See the panorama splitter.

1. Choose the ratio: 4:5 for the standard feed portrait, 3:4 when you want the grid tile to match, 1:1 for squares.
2. Pick the panel count. A wide panorama suggests its own count, and a set of photos works with a layout that puts a photo on each fold.
3. Compose the spread on one canvas. Move photos, add text and keep important words away from the folds.
4. Cut the canvas into equal panels on exact boundaries. A crop that is one pixel off shows as a hairline gap or a repeated strip.
5. Export every panel at the same size and in order, panel 1 first.
6. Post: open the composer, select panel 1, then the rest up to the last. Do not zoom or drag in the composer.

What do you do when the panels still do not line up?

Start with the composer, because that is where most breakage happens. Work through the steps below in order and stop at the first one that fixes it.

1. Close the draft and start the post again so no earlier crop remains.
2. Select the panels from 1 to the last, tapping slowly so the numbers appear in order.
3. Leave the crop frame alone. Do not pinch, zoom or drag any slide.
4. Check that all panels share one ratio. If one was exported at a different size, export the whole set again.
5. Compare with the editor. If a seam is off inside the editor too, the cut is the problem, not the composer.

How do you keep the picture sharp?

A small source stretched over many panels turns soft. A rule of thumb from carousel guides is about 1080 px of source per panel, so 4 panels want roughly 4,320 px. The social app also re-compresses uploads, so export the cleanest file you can and avoid editing the panels again in another app.

If your panorama is narrower than that, use fewer panels. Two crisp panels beat six soft ones.

Which picture ideas work best?

Not every photo suits a swipe. The ones that do give the eye a reason to keep moving, and they carry a clear line or object across the cuts.

• A wide landscape or skyline, where the horizon runs through every panel.
• A table or desk shot with objects spread along it, so each panel adds a new item.
• A set of photos with one object placed across each fold, so the next swipe completes it.
• A long headline that reads across two or three panels.
• A before and after pair that meets in the middle.

How should text work across a carousel?

Keep each word on one panel unless the effect is the point. Text that is cut by a fold forces the eye to rebuild the word on the next swipe, and at normal reading speed that fails. A long headline that is meant to travel across panels works only when it is large, short and readable in each slice.

Leave a margin of a few percent of a panel's width on each side of a fold. In Seamfold, seam check uses a margin of about 4 percent of a panel and counts every text layer that crosses a fold. Treat the count as a prompt to look, not as a rule. If the Headline across layout is what you want, keep it.

How do you check the result before posting?

Page through the panels the way a follower will, slowly and then quickly. Look for text that lands on a fold, objects that look cut in half by accident and a first panel that works alone in the grid. Swipe test in Seamfold does this in a generic post frame, and it ends with a row that shows your cover among three grid tiles.

If you plan to announce the post in stories, a short teaser helps people know to swipe. See the teaser card.

A short checklist before you post

• All panels have the same size and were exported in one batch.
• Panel 1 is selected first in the composer, then 2, 3 and so on.
• No pinch, zoom or crop was applied in the composer.
• No important text sits on a fold or near the edge of panel 1.
• The caption is ready, since it applies to the whole post.

Does the first panel need special care?

Yes. The profile grid shows the first panel as a 3:4 tile, so a title near the edge can be trimmed there. Check the cover before you post. The 3:4 grid cover guide has the numbers, and swipe test lets you page through the result first.

A worked example with a desk photo

Say you shot a desk from above: laptop on the left, a coffee in the middle, a notebook on the right. The photo is 5400 x 1500 px, so its ratio is 3.6. At 4:5 that gives 3.6 x 1.25 = 4.5, which rounds to 5 panels, or 4 on the free plan.

At 4 panels the spread is 4,320 x 1,350 px and the photo fills it with room to spare. Panel 1 shows the laptop, panel 2 the coffee, panel 3 the notebook, and panel 4 a blank corner that fits a short line of text. Put the line inside panel 4, away from the fold, and run the swipe test before you save.

Can a phone app do all this?

Yes. A phone is enough because the work is cutting and ordering, not heavy editing. The free plan in Seamfold covers 2 to 4 panels, and the app saves with add-only permission to Photos, so it never reads your library. Seamfold is still in development, so check the features page for what is planned at release.

Is there a mark on the panels?

On Seamfold's free plan the last panel carries a small "made with Seamfold" mark in the bottom right corner. Pro turns it off by default. If the mark would land on part of the picture that matters, add a plain strip of background or move the subject, because the mark is placed by the app and not by you.