About This Tool
Resize any image to exact pixel dimensions in seconds with no signup required. This free tool handles JPG, PNG, WebP, and other common formats while keeping your images completely private. Your photos are never uploaded to a server or stored anywhere. Social media platforms reject or crop images that do not match their required dimensions. An Instagram post needs 1080x1080 pixels, a YouTube thumbnail needs 1280x720, and a LinkedIn banner needs 1584x396. Manually opening a photo editor, entering dimensions, exporting, and checking file size is slow and repetitive when you have multiple images to prepare. This image resizer eliminates that friction. Select a platform preset or enter custom width and height values, adjust JPEG quality to control file size, and download the result with one click. The aspect ratio lock prevents accidental stretching or squishing. The quality slider lets you balance visual clarity against file size, which matters when optimizing for web page load speed or meeting upload limits. Your images stay completely private throughout the process. No image data is transmitted over the network or stored anywhere. This makes the tool safe for resizing screenshots with sensitive information, product photos before they are published, or personal images you prefer to keep private.
How the Resize Algorithm Works
When you click "Resize Image," the tool redraws your image at the target dimensions using high-quality bicubic interpolation, the best available resampling method for photographic content.
The output is exported as a JPEG at the quality level you selected. A quality of 85% is the default because it provides a good balance between visual fidelity and compression. At 85%, most images are visually indistinguishable from the original while being significantly smaller in file size. Dropping to 60-70% produces noticeable artifacts in gradients and fine text but works well for thumbnails and social media posts where compression is expected.
The resizing completes in milliseconds even for large images. There is no queuing, waiting, or watermark applied to your output.
Social Media Image Size Reference
Each platform enforces specific dimensions for different placements. Using the wrong size causes cropping, letterboxing, or rejection. Here are the sizes built into this tool:
- Instagram Post: 1080 x 1080 px (square). Feed posts display at 1080px wide. Rectangular posts are supported but square gets the most screen real estate in the grid.
- Instagram Story: 1080 x 1920 px (9:16 ratio). Stories fill the full phone screen vertically. Anything smaller is upscaled and blurred.
- Facebook Cover: 820 x 312 px on desktop, 640 x 360 px on mobile. The tool uses the desktop size since that is the primary upload target.
- Twitter/X Header: 1500 x 500 px (3:1 ratio). This banner appears at the top of your profile page.
- LinkedIn Banner: 1584 x 396 px (4:1 ratio). The personal profile background image. Company pages use 1128 x 191.
- YouTube Thumbnail: 1280 x 720 px (16:9 ratio). YouTube requires thumbnails to be at least 640px wide. 1280x720 is the recommended resolution.
Aspect Ratio Lock Explained
When the "Lock aspect ratio" checkbox is enabled, changing the width automatically calculates the corresponding height (and vice versa) to preserve the original image proportions. This prevents distortion where circles become ovals and text becomes stretched or compressed.
The calculation is simple: if the original image is 4000x3000 (4:3 ratio) and you set the width to 1200, the height is automatically set to 900 to maintain that 4:3 relationship. The formula is: new_height = new_width / (original_width / original_height).
Disable the lock when you intentionally want to change the proportions, such as converting a landscape photo to a square Instagram post where cropping is acceptable. When aspect lock is off, you have full control over both dimensions independently.
Selecting a preset always sets both dimensions to the exact values required by that platform, regardless of the lock setting. If you then switch to Custom and modify one dimension, the lock behavior resumes.
Optimizing Image File Size for the Web
Page load speed directly affects bounce rates and search rankings. Images are often the largest assets on a web page. Resizing to the exact display size and choosing the right quality level are the two most effective optimization steps.
A 4000x3000 photo displayed at 800x600 on a web page wastes bandwidth transmitting pixels the browser throws away. Resize to the actual display size first, then adjust quality. For photographic content, JPEG quality between 70-85% is the sweet spot. For images with sharp edges and text (screenshots, logos), PNG at full quality often compresses better than JPEG.
After resizing, consider running the output through a dedicated compression tool for additional savings. The quality slider here controls JPEG compression directly, but dedicated compression tools or WebP conversion can squeeze out an extra 20-30% without visible degradation.