Free Image Resizer by pixels or percent

Image size is one of the most quietly important details on the modern web. A photo straight out of a phone or camera can easily be 4,000 pixels wide and several megabytes in weight, far larger than any web page, email or social post actually needs. When that oversized file is dropped onto a website, the browser still has to download every one of those pixels before it can shrink the picture down to the few hundred it will actually display. The result is slower pages, higher bounce rates, wasted mobile data and, increasingly, a search-ranking penalty, because page speed and Core Web Vitals are part of how Google judges a site. Resizing the image to the dimensions it will really be shown at fixes the problem at the source and is one of the highest-impact things anyone can do for image performance.

Different destinations also demand different exact sizes, and getting them right matters more than people expect. Social platforms crop and re-compress anything that does not match their expected dimensions, so a profile picture, a story, a thumbnail or a cover banner each has a sweet-spot resolution that keeps your image crisp instead of blurry or awkwardly cut. Email newsletters break their own layout when a giant image overflows the column width, and some clients simply refuse to inline a file over a certain size. Marketplace listings, documentation screenshots, avatars and print templates all have target sizes too. Resizing up front lets you control precisely what people see rather than handing that decision to each platform's automatic, quality-careless processing.

It helps to think in two units. Resizing by pixels means you set an exact width and height, which is what you want when a layout, an upload form or a platform spec calls for a specific resolution such as 1200 by 630 or 512 by 512. Resizing by percent scales the whole image proportionally, so 50 percent halves both sides while preserving every relationship in the picture; that is ideal for a quick, uniform shrink when you do not have an exact number in mind. The aspect-ratio lock ties the two dimensions together so editing one recalculates the other, which prevents the most common mistake in resizing: accidentally stretching or squashing a photo by entering a width and height that do not share the original proportions. A quick way to sanity-check your numbers is to divide width by height and compare it to the original ratio: a 16:9 source should stay near 1.78, a square near 1.0, and a portrait below 1.0, so if your target figures drift away from that number you know the image is about to be distorted before you ever hit download.

One concept is worth understanding clearly because it determines how good your result looks: the difference between making an image smaller and making it larger. Shrinking an image, or downscaling, discards pixels the picture no longer needs, and with high-quality smoothing the outcome is almost always sharp and clean. Enlarging an image, or upscaling, is the opposite problem. There is no hidden extra detail inside the file, so the canvas can only stretch and interpolate what already exists, which produces soft, blurry or blocky edges. The practical rule is simple: always start from the largest original you have and resize down to what you need, and never try to recover resolution by scaling a small image up.

Knowing the common target sizes saves a lot of trial and error. For the web, content images are usually fine somewhere between 1200 and 1920 pixels on the long edge, while thumbnails sit around 300 to 600 pixels. Social platforms cluster around predictable numbers: roughly 1080 by 1080 for a square feed post, 1080 by 1920 for vertical stories and reels, about 1200 by 630 for link-share and Open Graph previews, and 1280 by 720 for video thumbnails. Email images generally want to stay at or under 600 pixels wide to fit a standard newsletter column. Print is a different world entirely: it is measured in DPI, so a 4 by 6 inch photo at 300 DPI needs around 1200 by 1800 pixels. Matching these up front means your image lands correctly the first time. There is also a quieter performance reason to nail the exact dimensions: when you serve an image at the size your layout actually reserves for it, you can declare its width and height in the markup, and the browser reserves the right amount of space before the picture loads. That eliminates cumulative layout shift, the jarring jump where text and buttons leap down the page as a late image pushes them around, which is both annoying to users and a tracked Core Web Vitals metric. High-DPI screens add one more wrinkle worth planning for: a retina display packs two or more physical pixels into every CSS pixel, so an element drawn at 400 pixels wide on the page looks crisp only if you feed it an 800-pixel, or 2x, asset and let the browser pack it in. The practical workflow is to resize to twice your display size for the sharp version and keep the original for anything larger.

Just as important as the result is what happens to your file along the way. This resizer runs entirely inside your browser using the HTML Canvas API, which means no upload step and no server ever sees your picture. Sensitive screenshots, personal photos, unreleased client work, ID documents and internal diagrams all stay on your own machine, so there is nothing to leak and nothing to delete later. Because the image is redrawn onto a fresh canvas, the export is also stripped of the original EXIF metadata such as GPS coordinates, camera model and timestamps, which is a genuine privacy benefit when you share photos publicly. You can also choose the output format at export time, saving a JPG, PNG or WebP depending on whether you need the smallest file, transparency or the best modern compression.