Resizing an image sounds simple, but doing it wrong results in blurry, distorted, or unexpectedly large files. This guide explains the difference between resizing and compressing, when to do each, and the exact dimensions each platform needs.
These are distinct operations that affect the file in different ways:
| Operation | What changes | When to use it |
|---|---|---|
| Resize | Pixel dimensions (width × height) | When the image is too large in pixels for the space it will occupy |
| Compress | File weight (KB/MB) via compression algorithm | When the image is too heavy even though its dimensions are correct |
| Both | Dimensions and weight | High-res camera photo destined for web or email |
💡 Practical rule: if your image is wider than 1920 px for web use, resize first. If it still weighs more than 200 KB after resizing, then compress. Doing both together is the most efficient approach.
ComprimirPro includes a resize function that runs entirely in your browser — no server upload required:
Change dimensions and compress in one step. No sign-up, no file uploads to any server.
⚡ Resize free| Platform | Recommended size | Ratio |
|---|---|---|
| Instagram feed (square) | 1080 × 1080 px | 1:1 |
| Instagram Stories/Reels | 1080 × 1920 px | 9:16 |
| Facebook cover | 820 × 312 px | 2.63:1 |
| Twitter/X post image | 1200 × 675 px | 16:9 |
| LinkedIn article image | 1200 × 627 px | 1.91:1 |
| Pinterest Pin | 1000 × 1500 px | 2:3 |
If you change the width without adjusting height proportionally, the image becomes distorted — faces look squashed, objects appear stretched. This is called aspect ratio distortion.
object-fit: cover so the browser fits the image inside a container without distortion.The short answer: not entirely. When enlarging (upscaling), software has to "invent" pixels that didn't exist. Results depend on the method:
⚠️ Never enlarge a small image just to publish it. If the original is low-resolution, find a higher-resolution version instead of upscaling what you have. Upscaling only makes sense when no higher-quality version exists.
Generally yes, because there are fewer pixels to store. A 4000 × 3000 px image reduced to 1200 × 900 px will have 9× fewer pixels and a significantly smaller file size. But if you save the resized image without compression, it may still be heavier than ideal. Best practice: resize and compress at the same time.
Pixels measure dimensions (how many color points the image has). MB/KB measure file weight (how much storage it takes). An image can have many pixels but low weight if well compressed, or few pixels but large weight if saved uncompressed (e.g., TIFF or BMP without compression).
DPI (72, 96, 300) does not matter for web — what matters is pixels. A monitor doesn't understand DPI; it simply displays pixels. Always export at the pixel dimensions you need and don't worry about DPI when exporting for screens.
Yes. ComprimirPro lets you load multiple images and process them all with the same resize and quality settings, downloading the results as individual files.