A carousel can look clear on screen and still lose meaning when someone can’t see its images. Writing one general description for the whole post misses what changes from slide to slide. Instead, draft concise alt text for each image while you prepare the carousel. Describe the visual detail a viewer needs to understand that slide, rather than repeating its on-slide copy or pasting in the caption.
For a florist’s “keep cut flowers fresh” carousel, a slide might say “Trim the stems” while the photo shows scissors cutting them at an angle over a sink. Its alt text could be: “Close-up of scissors cutting flower stems diagonally over a sink.” A later slide showing a vase with leaves removed from the submerged stems needs a different description. Before publishing, read each description alongside its slide and check two things: does it match the final image, and does it add information the text alone doesn’t give? If you reorder or replace a slide, check its alt text again. How do you prepare and review alt text for your carousels?
Your point about not repeating on-slide copy is useful. For Instagram carousel alt text, I’d keep a numbered draft: 01 | notebook thumbnail | Open notebook with three dates circled; 02 | calendar thumbnail | Calendar with Friday highlighted. Keeping each draft beside its slide thumbnail makes the mapping easy to review.
The thumbnail pairing is a useful way to keep each description tied to the right slide. I’d add one check for infographic slides: does the alt text convey the comparison, not just name the graphic? Say a slide has two bars showing saves rising from 20 in week 1 to 65 in week 4, while views stay near 1,000. Its alt text could say exactly that, rather than “Bar chart of engagement.” For Instagram carousel alt text, that difference lets someone understand the slide’s takeaway without seeing the bars.
For infographic slides, the comparison needs its measuring stick too. In Instagram carousel alt text, include units or the baseline when leaving them out would change how a difference reads, such as a percentage-point change versus a percent change.
Keep the takeaway within what the chart shows: a trend or association describes what moved, not what caused it.
Your point about including the baseline matters especially when the chart uses percentages. For a chart comparing two completion rates, alt text could read: “Rate A rose from 20% to 25%, a five-percentage-point increase. Rate B rose from 20% to 21%, a five-percent increase relative to its 20% baseline.” Both changes can be called “five,” but they are different sizes. Naming the unit and starting value makes that clear without claiming the chart explains why either rate moved.