Aspect ratios explained, and why your photos keep getting cropped

An aspect ratio is the relationship between width and height, independent of size. A 4000 × 3000 photo and a 800 × 600 photo are both 4:3. Two images with the same ratio can be scaled into each other perfectly; two with different ratios cannot, and something has to give.

The ratios you will meet

Cameras mostly produce 3:2 — a legacy of 35mm film — while phones and micro four-thirds sensors often produce 4:3. Video is 16:9. Social feeds prefer 4:5 portrait and 1:1 square. Stories and reels are 9:16. Print sizes are their own family: 4 × 6 is 3:2, but 5 × 7 and 8 × 10 are neither.

Nothing in that list matches anything else reliably, which is why cropping is not an edge case but the normal state of affairs.

Three ways to reconcile a mismatch

Crop. Keep the target ratio and discard what falls outside it. The image stays undistorted and part of it is gone. This is what platforms do to your uploads when you do not do it yourself.

Pad. Keep the whole image and add space to reach the target shape. Nothing is lost, but the subject occupies less of the frame and you have introduced a background colour that needs to look deliberate.

Stretch. Force the image into the target shape. This distorts, obviously and unflatteringly on anything containing people or straight lines. There are legitimate uses — tiling textures, abstract backgrounds — and portraits are not among them.

The focal point is the real decision

When you crop, the ratio decides how much is lost and the focal point decides which part. Centre is the default and is wrong in two very common situations.

Full-length portraits: a centred square crop cuts through the torso and removes the face. A top-weighted crop keeps heads in frame across an entire shoot.

Flat lays and low-sitting products: the subject occupies the bottom of the frame and a centred crop clips it. A bottom-weighted focus preserves it.

Setting this once for a batch is usually enough, with individual overrides for the few frames where the subject sits somewhere unusual.

Shoot with the crop in mind

If you know an image will end up square, leave room around the subject when you shoot. Photographers call this shooting loose, and it costs nothing at capture time while saving the entire frame later. The reverse — trying to reconstruct a 9:16 story from a tightly framed landscape — is not possible.

A note on multiples

There is no single ratio that works everywhere, so plan for several outputs from one source. Process the batch to 4:5 for the feed, then reprocess the same originals to 9:16 for stories with a different focal point. Because the originals stay loaded, this is two passes rather than two imports — and both outputs are cropped by you rather than by an algorithm.

The ratios, as numbers

Ratios are easier to reason about as decimals, because it makes the size of a mismatch obvious.

Ratio	Decimal	Where it comes from
9:16	0.56	Phone screens: stories, reels, shorts
2:3	0.67	Pinterest; camera frame turned portrait
3:4	0.75	Phone camera turned portrait
4:5	0.80	Instagram portrait posts
1:1	1.00	Square: marketplace grids, avatars
5:4	1.25	Etsy listings; 8×10 print
4:3	1.33	Phone and micro four-thirds sensors
3:2	1.50	Most cameras; 4×6 print
16:9	1.78	Video, thumbnails, presentations
1.91:1	1.91	Link preview cards

Converting between neighbours in that table costs little. Converting from 16:9 to 9:16 — 1.78 to 0.56 — discards around 70% of the frame, which is why horizontal footage repurposed for stories so often looks like a mistake.

Working out what a crop costs

The arithmetic is simple and worth doing before a batch rather than after. Scale the image so the smaller relative dimension fits, then measure what falls outside.

A 4000 × 3000 photograph (1.33) cropped to square keeps a 3000 × 3000 region: 75% of the pixels, with 500 pixels lost from each side. The same photograph cropped to 9:16 keeps roughly 1688 × 3000 — about 42% of the frame, and more than half the width gone.

Anything below about 60% retention deserves a look at whether padding would serve the image better than cropping.

Ratios that lie

Two things routinely confuse the picture.

EXIF orientation. A portrait photograph from a phone is often stored as a landscape frame with a rotation flag. Software that ignores the flag reports the wrong ratio and crops the wrong axis, which is why images occasionally arrive sideways from one tool and upright from another.

Non-square pixels. Rare now, but some video-derived stills store rectangular pixels, so the stored dimensions do not match the displayed shape. If an image looks stretched at its native size, this is usually why.

Designing for multiple ratios at once

If you know a photograph will be published at several ratios, compose for the most restrictive one at capture time and let the others be generous crops of it.

In practice that means keeping the subject within the central square, and leaving deliberate space above and below for vertical formats. Photographers call this shooting loose. It costs nothing when you take the picture and cannot be added afterwards.