How to Crop an Image to an Exact Aspect Ratio (16:9, 1:1, 4:5)
Aspect ratio is a shape, not a size. Here is how to crop to an exact ratio, which ratio each platform wants, and how to avoid cropping through your subject.
Updated August 11, 20265 min read
Aspect ratio confuses people because it looks like a size and is not one. 16:9 does not mean 16 pixels by 9 pixels — it means the width is 16 units for every 9 units of height, which is equally true of 1920 × 1080, 1280 × 720 and 640 × 360. Ratio is the *shape* of the rectangle. Size is how many pixels fill it. Getting that distinction straight makes every platform requirement obvious instead of arbitrary.
The ratios that actually matter
| Ratio | Shape | Where it is used | Common size |
|---|---|---|---|
| 1:1 | Square | Profile pictures, Instagram feed, product grids | 1080 × 1080 |
| 4:5 | Tall portrait | Facebook and Instagram feed — though Instagram now also takes a taller 3:4 (1080 × 1440) | 1080 × 1350 |
| 9:16 | Full vertical | Stories, Reels, TikTok, Shorts | 1080 × 1920 |
| 16:9 | Widescreen | YouTube, X, website heroes, presentations | 1920 × 1080 |
| 3:2 | Classic photo | Most DSLR and mirrorless output, 6×4 prints | 3000 × 2000 |
| A4 | ≈1:1.414 | Documents and print | 2480 × 3508 at 300 DPI |
Notice that your phone almost certainly shoots 4:3, a dedicated camera usually 3:2, and almost nothing online wants either. That mismatch is why cropping is a step in nearly every workflow rather than an occasional fix — a 3:2 photo dropped into a 1:1 slot loses a third of its width, and the platform decides which third unless you decide first.
Crop to the ratio, then resize to the pixels
These are two separate operations and doing them in the wrong order causes most of the frustration. Cropping sets the shape. Resizing sets how many pixels fill that shape. If you resize first and crop second, you have thrown away pixels you then crop away anyway, and you may end up below the platform's minimum width.
Straighten first if the horizon is off
Rotation crops the corners, so a straightening pass after you have already cropped will eat into your composition. Use rotate and flip before anything else.
Crop to the ratio with the ratio locked
Open the cropper and set the ratio before you drag. A locked ratio means you cannot accidentally produce 1.02:1 and wonder why the platform added bars. The cropper has no 4:5 preset: for that shape, use Free Form and frame it by eye, or in the resizer choose Width & height, lock the aspect ratio, enter 1080 × 1350 and pick Fill & crop.
Resize to the target pixel size
Now set the exact dimensions in the resizer. Because the shape already matches, this is a pure scale with no distortion.
Deciding what to cut
A ratio change always removes something. The question is only whether you choose what, or the platform's automatic centre crop chooses for you. Three rules cover almost every case:
- Never cut through a face at a joint. Cropping at the neck, wrist or ankle looks like an accident. Cut mid-limb or well clear of the head.
- Keep the eyes near the top third. The single most reliable portrait rule, and it survives every ratio change.
- Leave room in the direction of movement or gaze. A subject looking left with no space on the left feels cramped; the same crop mirrored feels composed.
When one image has to work in several ratios, do not crop tightly for the widest one and then try to reuse it. Crop each ratio from the original. Cropping a crop compounds every earlier decision and quickly leaves you with no room to move.
Lock a ratio, drag to frame it, export. Everything runs on your device — the image is never uploaded.
Crop an imageWhy platforms add bars to your image
If you upload a 4:3 image where 16:9 is expected, the platform has two options: crop it, or pad it with bars to make it fit. Which it chooses varies, and neither is what you wanted. Bars waste screen space and make a post look amateurish; an automatic crop takes the centre, which is rarely where your subject is.
The fix is to supply the exact ratio the destination expects. For social platforms the social media resizer has platform presets, so you are not translating a documentation page into numbers by hand. For everything else, work out the ratio the slot needs and crop to it deliberately.
Ratio maths, briefly
To find the pixel height for a chosen width, multiply the width by the second number and divide by the first. A 16:9 image 1440 pixels wide is 1440 × 9 ÷ 16 = 810 pixels tall. To check whether an existing image is already at a ratio, divide width by height: 1.778 is 16:9, 1.5 is 3:2, 1.333 is 4:3, 0.8 is 4:5, 0.5625 is 9:16.
That last check is worth doing before you assume an image needs cropping. Plenty of screenshots and exports are already at a standard ratio, and a crop that changes 1.778 to 1.779 gains nothing while costing you pixels. The image analyzer reports the exact dimensions if you would rather not divide by hand.
One last habit: keep the uncropped original. Ratios in use change — Instagram moved from 1:1 to 4:5 and, in 2025, to a 3:4 grid, and something else will follow — and the only cheap way to keep up is to still have the full frame.
Frequently asked questions
What is the difference between aspect ratio and resolution?
Aspect ratio is the shape of the rectangle — the proportion of width to height. Resolution is how many pixels fill it. 1920 × 1080 and 1280 × 720 are both 16:9; they differ in resolution, not shape. Crop sets the ratio, resize sets the resolution.
How do I crop a photo to 16:9 without losing the subject?
Lock the ratio in the cropper first, then position the frame rather than resizing it. Going from a 3:2 camera photo to 16:9 removes height, so check that you are not cutting through the top of a head — move the frame up rather than accepting the default centre position.
Does cropping reduce image quality?
Cropping removes pixels but does not degrade the ones that remain, so quality per pixel is unchanged. What it reduces is total resolution, which matters if the result then falls below a platform's minimum width. Crop from the largest original you have.
What aspect ratio should I use for Instagram?
3:4 portrait (1080 × 1440) for feed posts: since 2025 it is the tallest feed shape Instagram accepts, and it matches the profile grid. 4:5 (1080 × 1350) still works and suits Facebook as well. Use 1:1 square when the same image also has to work on other platforms, and 9:16 for Stories and Reels.