Resize Images Online
Resize images by pixel dimensions or percentage, keeping the aspect ratio. Batch-resize a whole folder in your browser with nothing uploaded.
Runs entirely in your browser — nothing is uploaded
Dimensions or percentage
By dimensions targets an exact pixel size. Fill in only the width and the height is calculated for you, which is what you want almost every time — it guarantees the proportions survive. Fill in both and each image is scaled to fit inside that box, so a batch of mixed portrait and landscape photos all come out no larger than the space you allowed.
By percentage scales every image relative to its own size. Use it when the pictures differ and you want them all reduced by the same amount rather than forced to a common size.
What size should images be?
The rule that covers most cases: match the space the image occupies, then double it for high-density screens.
- Blog or article images — 1200 to 1600 pixels wide.
- Full-width banners — 1920 pixels is plenty.
- Thumbnails and avatars — 300 to 600 pixels.
- Email attachments — 1600 pixels keeps the file small enough to send while staying sharp on any screen.
Beyond about 2400 pixels wide you are almost always shipping bytes nobody sees. The browser downloads every one of them and then throws the surplus away, which is pure cost to your visitor.
Resizing is the most effective way to shrink a file
File size scales with pixel count, and pixel count scales with the square of the dimensions. Halving both width and height removes three quarters of the pixels — a far bigger saving than any quality slider can deliver without visible damage.
The best results come from doing both, in order: resize to roughly twice the display size first, then compress. A 5 MB phone photo routinely becomes 150 KB this way with nothing visibly lost.
Enlarging does not add detail
Scaling up past 100 percent cannot recover information that was never captured. The browser interpolates — it invents intermediate pixels by averaging their neighbours — and the result is soft rather than sharp.
Up to about 150 percent this is tolerable for a background image. Beyond that it is obvious. If you need a larger version, the answer is always to find the original file rather than to enlarge a small copy.
Aspect ratio, and when to break it
With the ratio locked, proportions are preserved and nothing is distorted. Unlocking it forces both dimensions exactly, which stretches or squashes the picture — occasionally useful for a texture or a background, almost never right for a photograph of a person.
If you need an exact square from a rectangle without distortion, what you actually want is cropping rather than resizing: cutting away the excess rather than compressing it.
Why there is a maximum size
Browsers limit how large a drawing canvas can be, and the limit is much lower on phones than on desktops. Ask for more and the browser hands back a blank image rather than an error.
Rather than let that happen, this tool caps the output at the largest size the device can safely handle and tells you when it did. You get a real image slightly smaller than requested, instead of a mysterious empty one.
Frequently asked questions
Will resizing distort my image?
Not if you leave the aspect ratio locked, which is the default: set either width or height and the other follows automatically. Unlocking it lets you force exact dimensions, which stretches or squashes the picture. That is occasionally what you want, but it is rarely what you want by accident.
Can I make an image larger?
You can, but a small picture enlarged does not gain detail — the browser only invents intermediate pixels, so the result looks soft. Enlarging past about 150 percent is visibly blurry. If you need a bigger version, go back to the original file at its full size.
What size should images on a website be?
Match the space they occupy, then double it for high-density screens. A 600-pixel-wide column wants roughly a 1200-pixel image. Full-width banners are usually fine at 1920. Anything beyond 2400 pixels wide is almost always wasted bytes that slow the page down for nobody's benefit.
Does resizing also make the file smaller?
Substantially, and it is the most effective way to shrink a photo. File size scales with the number of pixels, so halving both width and height removes about three quarters of them. Resizing first and compressing afterwards beats compressing an oversized image hard.
Why is there a maximum output size?
Browsers cap how large a drawing canvas can be, and the cap is much lower on phones than on desktops. If your requested size exceeds what the device can allocate, the tool scales down to the largest safe size and tells you, rather than silently handing back a blank image — which is what an oversized canvas actually returns.