Best Instagram Carousel Size and Dimensions
The best Instagram carousel size is 1080x1350px, a 4:5 vertical ratio. This carousel size takes up more feed real estate (more pixels visible = more attention), respects the maximum vertical ratio Instagram allows, and is what the algorithm has prioritized since 2024. This page explains why 4:5 beats 1:1 square, which official dimensions Instagram supports, and how Krossel ships your carousels in the optimal size automatically so you do not have to think about it.
Official Instagram dimensions accepted
Instagram supports 3 ratios for feed posts: 1:1 (1080x1080px, square), 4:5 (1080x1350px, vertical) and 1.91:1 (1080x566px, landscape). For a carousel, all slides must share the same ratio, you cannot mix 1:1 with 4:5 in the same carousel. 4:5 is the maximum vertical allowed (anything taller gets cropped). 1080px width is the minimum for good quality, lower resolutions look pixelated on modern screens.
Why 1080x1350px (4:5) wins
The Instagram feed shows posts in a fixed-width slot. At 1:1, the post height equals its width. At 4:5, height is 25% larger. More height means more visible pixels before the user scrolls. Public Hootsuite and Sprout Social data shows engagement 5 to 15% higher on 4:5 vs 1:1 simply because the post looks bigger in the feed. For carousels, this is amplified: slide 1 has more room for text, the hero image looks more striking, and the swipe-right cue gains visual urgency.
When 1:1 still makes sense
1:1 still makes sense in two cases: a tightly curated grid (1:1 keeps grid aesthetics uniform), or when the post needs to flow well cross-platform (Twitter/X and LinkedIn handle 1:1 better than 4:5). If you mostly post on Instagram and want maximum engagement, go 4:5 every time. If you want to reuse the same PNG on LinkedIn or Twitter, 1:1 is more flexible. Krossel defaults to 4:5 since the focus is Instagram, but you export PNGs freely for any platform.
How Krossel handles carousel size
Each slide renders in a React container at 1080x1350px (true resolution, not CSS scaling). The AI gets the size constraint and writes copy that fits without overflow, you will not see clipped text like when pasting into Canva. When you publish via the Instagram API, PNGs upload at max quality (no double compression that happens with mobile app uploads). And when you export the zip for manual posting, files come as 1080x1350px PNGs named in order (slide-1.png, slide-2.png) for sequential upload.
Common size mistakes that break the post
Slides with mismatched ratios (one 1:1, another 4:5): Instagram rejects the entire carousel, you have to rebuild it. Width below 1080px: pixelated PNGs after compression. PNG with transparency: some Instagram clients render a generic white background instead of the design, always export with a solid fill. File above 30MB: also rejected, for HD carousels compress without losing visible quality (PNG-8 or WebP-converted). Krossel avoids all of this automatically because it renders everything at the right format from the start.