Resize Image for Instagram — Free, No Signup

How to do it

Drop your photo onto the upload box.
Enter the dimensions for your post: 1080 × 1080 for a square, 1080 × 1350 for a portrait, 1080 × 1920 for a story.
Leave the aspect ratio locked unless you want Instagram to crop for you.
Download the resized image and upload it.

The dimensions that matter

Instagram accepts three shapes for feed posts. Square is 1080 by 1080. Portrait is 1080 by 1350, the 4:5 ratio, and it occupies the most vertical space in the feed, which is why most accounts favour it. Landscape is 1080 by 566 at 1.91:1, and it is the smallest presence of the three. Stories and Reels are 1080 by 1920 at 9:16. Uploading at 1080 pixels wide is the sensible ceiling: the app downsamples anything larger to that width anyway, and doing that step yourself means you control the resampling rather than accepting theirs.

Crop before you resize, not after

Resizing changes dimensions; it does not decide what stays in frame. If your source photo is 3:2 and you resize it straight to a square with the aspect lock off, everything gets squashed horizontally and faces look wrong. The right order is to crop to the target ratio first so the composition is what you want, then resize the cropped result to the exact pixel dimensions. With the aspect lock on, this tool refuses to distort — enter one dimension and it fills in the other, which is the safe default for most people.

Why the app degrades your photo

Instagram re-encodes every upload. If you hand it a 12-megapixel file it has to downscale by a large factor and compress at the same time, and both operations lose detail. Hand it a file already at 1080 pixels wide and lightly compressed, and its pipeline has far less to do. Sharp graphics, text overlays, and fine patterns benefit most from this, because those are exactly the details that survive a single careful resize but not an aggressive automatic one.

How the downscaling works here

Large reductions are done in successive halving steps rather than a single jump. Shrinking a 4000-pixel photo straight to 1080 in one pass throws away most of the source pixels without consulting them, which produces aliasing on fine detail — brick, fabric weave, hair, text. Halving repeatedly averages each stage into the next, so the detail is folded down rather than dropped. The difference is most obvious on patterned clothing and architectural photos, where a single-step resize produces shimmer that a stepped one does not.

Format and quality

The resizer preserves the original format: a PNG stays a PNG with its transparency, a JPEG stays a JPEG, a WebP stays a WebP. Input is capped at 5 MB and output at 10000 pixels on a side. If your resized file is still heavier than you want, run it through the compressor afterwards — resize first, compress second, always in that order, because compressing before resizing wastes the compression on pixels you are about to discard.

Frequently asked questions

What size should an Instagram post be?

1080 by 1080 for square, 1080 by 1350 for portrait, and 1080 by 566 for landscape. Portrait takes the most feed space, so most accounts use it.

What size is an Instagram story?

1080 by 1920, a 9:16 ratio. The same dimensions apply to Reels.

Should I upload larger than 1080 pixels wide?

There is no benefit. Instagram downsamples to 1080 regardless, and doing the resize yourself gives a cleaner result than its automatic pass.

Why did Instagram crop my photo?

It did not match a supported ratio. Crop to the target ratio before resizing, otherwise the app makes that decision for you.

Will resizing stretch my photo?

Not with the aspect lock on — enter one dimension and the other fills in proportionally. Turn the lock off only when you deliberately want a stretch.

Should I compress before or after resizing?

After. Compressing first spends effort on pixels you are about to throw away, and the second pass compounds the loss.

Resize an Image for Instagram — Free, No Signup