Crop an image online: formats, ratios and best practices
You've cropped your photo. Now it's cut off on Instagram and squashed on LinkedIn. That's not a bug, it's the wrong aspect ratio. This guide explains which area to select, what ratio to apply based on your use case, and how to crop without losing quality in your browser.
7 min read
En résumé
Cropping an image means selecting a precise zone and removing the rest. Unlike resizing, cropping reduces the visible surface without altering the resolution of the pixels kept. Impmage lets you crop for free online, directly in your browser, with no installation needed.
Crop vs resize: the confusion that costs money
Both operations change an image’s dimensions. That’s where the similarity ends.
Resizing means reducing or enlarging the entire image. The visual content stays intact, each element is simply smaller or larger. Nothing is removed.
Cropping means removing a portion of the image to keep only a specific zone. The pixels in the kept zone don’t move: it’s the rest that gets eliminated.
In practice: if your photo needs to fit in a smaller space without losing any information, resize. If it needs to adapt to an imposed format (Instagram square, LinkedIn portrait) and your subject doesn’t fill the entire frame, crop first.
The order matters: crop before resize, not the other way around. Concrete example: you have a 4,000 × 3,000 px photo to prepare for Instagram Stories (1,080 × 1,920 px). If you resize first to 1,080 × 810 px, you no longer have the height for a 9:16 ratio — you’ll need to enlarge, creating blur. Start from the full-resolution source, crop to the right ratio, then resize.
Our guide to resizing explains why enlargement degrades quality.
Aspect ratio
The relationship between the width and height of an image, expressed as a proportion (e.g., 16:9, 4:3, 1:1). The aspect ratio determines the shape of the image, not its resolution or weight.
Aussi appelé : aspect ratio, image proportions
Ex : A photo at 3,000 × 2,000 px has a 3:2 ratio. Cropped to 2,000 × 2,000 px, it becomes 1:1 (square). The pixels kept retain their original resolution.
Choosing the right ratio before cropping
The cropping decision is made before opening the tool — not after. Knowing where your image will be published determines the ratio. Here are the reference values in 2026.
Ratios and recommended dimensions by use case
| Use case | Ratio | Dimensions (px) | Notes |
|---|---|---|---|
| Instagram — square (feed) | 1:1 | 1,080 × 1,080 | Versatile format: displays well on all screens |
| Instagram — portrait (feed) | 4:5 | 1,080 × 1,350 | Maximizes feed space: displayed as 1:1 square in profile grid |
| Instagram — landscape (feed) | 1.91:1 | 1,080 × 566 | Supported format, but less visible than portrait |
| Instagram Stories / Reels | 9:16 | 1,080 × 1,920 | Full-screen vertical: strict cropping required |
| LinkedIn — post image | 1.91:1 | 1,200 × 628 | Square possible: 1,200 × 1,200 px |
| X (Twitter) — post image | 16:9 | 1,200 × 675 | Standard landscape format for timeline |
| Facebook — post image | 1.91:1 | 1,200 × 630 | Same ratio as LinkedIn and Open Graph |
| TikTok — video/visual | 9:16 | 1,080 × 1,920 | Identical to Instagram Stories |
| YouTube — thumbnail | 16:9 | 1,280 × 720 | Text and faces in center 70% — edges masked by mobile UI |
| Profile picture (all networks) | 1:1 | 400 × 400 min | Displayed as circle on most platforms |
| A4 print (portrait, 300 DPI) | 1:√2 | 2,480 × 3,508 | ISO 216 standard: for quality printing |
| Open Graph / link sharing | 1.91:1 | 1,200 × 630 | Facebook, LinkedIn, messengers: link preview |
Sources: help.instagram.com, linkedin.com/help, support.google.com/youtube, support.twitter.com (May 2026). Platforms update recommendations regularly, verify before a major campaign.
One point guides often overlook: aspect ratio is not the same as minimum resolution. Instagram accepts 1:1 starting at 320 × 320 px, but below 1,080 × 1,080 px, the image will be enlarged by the platform and lose sharpness.
The Instagram grid paradox
You post in 4:5 to take up maximum space in the feed. But in your profile grid, all thumbnails display as 1:1 squares — Instagram auto-crops to center. Result: a well-composed 4:5 portrait can have the face cut off in the grid. If your account is a showcase (portfolio, brand), compose your subject in the central 1:1 zone of your 4:5 image. You get the portrait format in the feed and a correct thumbnail in the grid.
Stories and Reels: leave a safety margin
The 9:16 format (1,080 × 1,920 px) is theoretically full-screen. In practice, Instagram hides the ~13% top and bottom with the interface (icons, text, buttons). If your subject is at the top or bottom, plan a 250 px margin on each side to avoid auto-cropping. That’s about 500 px of height “sacrificed” out of 1,920 px.
Crop an image with Impmage in 4 steps
Processing happens client-side. No file leaves your device.
Crop an image with Impmage
- 1
Load the image
Drag your image into the drop zone or click 'Choose a file'. Accepted formats: JPEG, PNG, WebP, AVIF.
Load the image at its original resolution: always crop from the high-resolution source, not from an already-compressed version.
- 2
Access the Crop tool
Click the 'Crop' tab in the toolbar. The current image dimensions display. You can choose a preset ratio (1:1, 4:5, 16:9, 9:16) or define a free zone.
Preset ratios match standard social network formats: use them directly if you're publishing to a known platform.
- 3
Adjust the crop zone
Move the frame to position your main subject in the kept zone. Verify that important elements (face, product, text) aren't cut off.
Place the main subject in the upper third of the frame for a more natural result, see the rule of thirds section.
- 4
Download the cropped image
Click 'Download'. The image is exported in its original format with new dimensions. Processing stays local, no data passes through a server.
If you also want to compress or convert the format, chain the tools in Impmage before final download.
Crop without distortion: focal zone and rule of thirds
Choosing a ratio is easy. Positioning the crop zone correctly is where most errors happen.
Focal zone
The region of an image containing the main subject: the part you can't afford to cut. Identifying the focal zone before cropping avoids losing key composition elements.
Aussi appelé : point of interest, main subject
Ex : In a portrait photo, the focal zone includes the face and shoulders. In a product photo, it's the product and immediate context.
The rule of thirds is a composition guide: mentally divide the image into a 3 × 3 grid. The intersection points are where the eye naturally rests. Placing your main subject on one of these points (rather than dead center) gives a more balanced result in virtually all formats.
Rule of thirds
Composition principle that divides the image into 9 equal zones (3×3 grid). Placing the main subject on one of the 4 intersections creates a visually more balanced composition than strict centering.
Aussi appelé : photographic composition, power points
Ex : In a landscape photo, the horizon is placed on the upper or lower third, never in the middle. This gives more visual weight to the sky or ground depending on subject.
In practice, two mistakes recur constantly:
- Cropping without checking edges: a finger cut off, a logo truncated, text partially outside the frame. Check all four edges before confirming.
- Forcing an impossible ratio: if your photo is 16:9 landscape and you want 1:1, you lose 44% of the surface. Identify your focal zone before choosing the ratio, not after.
What cropping does (and doesn’t do) to quality
Cropping mechanically reduces file weight — fewer pixels to store. A 3,000 × 2,000 px photo cropped to 1,500 × 1,500 px keeps 37% of the original pixels. A 2.5 MB JPEG file drops to around 0.9–1 MB, depending on content and original compression level.
What doesn’t change: the resolution of pixels in the kept zone. If your source is sharp at 300 DPI in the cropped zone, the exported file will be sharp at 300 DPI. Cropping doesn’t degrade quality — it preserves it by eliminating excess.
What cropping doesn’t do: compress the file. A 1,080 × 1,080 px cropped image can still weigh several megabytes if not compressed. Cropping and compression are two distinct (and complementary) steps.
Cropping ≠ compression
Cropping an image reduces its dimensions and weight proportionally, but it’s not compression. For web publishing, chain both operations: crop first for the right format, then compress to reduce residual weight.
One special case: PNG with transparency. Cropping a transparent PNG preserves the alpha channel in the cropped zone. The transparent background stays transparent, no loss of transparency data.
Frequently asked questions
How do I crop an image online for free? ▾
What aspect ratio should I use for Instagram in 2026? ▾
What's the difference between cropping and resizing an image? ▾
How do I crop a photo without losing quality? ▾
Can you crop a transparent PNG online? ▾
Does cropping an image preserve EXIF metadata? ▾
How do I crop an image for A4 printing? ▾
How do I crop an image without distorting it? ▾
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GlitchGhost
Independent developer
Independent developer specializing in web performance tools and image optimization.
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