Upload forms almost always cap the file size rather than the dimensions — 20 KB for a signature,
50 KB or 100 KB for a photo. This resizer works to that number directly, inside your browser,
with no upload and no watermark. Three steps:
Upload your photo. Drag it in or click to browse. One image, or up to 50 at once.
Set the target. Switch Target File Size to Under, then pick 20, 50, 100, 200 or 500 KB, or type any number you need.
Process and download. One image downloads as a single JPG. A batch comes back as a ZIP.
How the target is reached
File size has two dials: image quality and the number of pixels. The tool turns the quality dial
first, searching for the highest quality that still fits under your limit. That alone is often
enough for a small or medium photo.
For a large photo it is not. A 12 megapixel camera shot cannot reach 20 KB at any JPG quality —
push quality low enough and you get a blocky mess that is still over the limit. So when quality
runs out, the tool reduces the width and height instead and then raises the quality back up to
use whatever budget is left. In one test a 2400 × 1800 photo asked for 50 KB came back at
981 × 736 with quality near 72 percent — far better looking than the same photo crushed to the
lowest quality at full size. The exact figures depend on the photo, since a busy image needs
more bytes than a plain one; the tool always reports the size and dimensions it ended up with.
If you need the dimensions untouched, untick Let the tool adjust width and height.
The tool will then work on quality alone, and if your target turns out to be unreachable that way
it says so plainly instead of handing back a file that misses the limit.
Making a file larger instead
Some forms set a minimum size and reject anything smaller. Switch Target File Size to
At least and enter that minimum. Images that already clear it are simply saved
at the quality you choose — they are never padded out for no reason. Anything that falls short
has its quality raised first, and then its dimensions, until the file reaches your figure. Very
few tools offer this, which is usually why people end up stuck on it.
Why JPG gives the most accurate result
JPG and WebP have a quality setting, so their file size can be tuned in fine steps — that is what
makes hitting 50 KB rather than 63 KB possible. PNG is lossless and has no quality dial at all,
so the only way to change a PNG's size is to change its dimensions. Pick JPG for
KB targets. It is also the format most upload forms ask for.
Setting dimensions as well
A KB target and a pixel size can be used together. Set the width and height, or a social media
preset, or a percentage scale, and the KB target is applied to that result. Where the two conflict —
a large fixed size and a very small KB limit — the tool will reduce the dimensions further unless
you have locked them, and either way it reports what it actually produced.
Frequently Asked Questions
Set Target File Size to Under, pick 50 from the presets or type any number of KB, and process. The tool searches for the highest JPG quality that still fits under your limit, and if quality alone cannot get there it reduces the width and height as well. The result tells you the size it actually reached.
Yes. Switch Target File Size to At least and enter the minimum KB the form requires. Images that already clear the minimum are saved at the quality you set, so nothing is inflated needlessly. Anything below it has its quality raised first and then its dimensions, until the file is at or above your figure. Some upload forms reject files that are too small, which is why this mode exists.
Only when they have to. A 12 megapixel photo cannot reach 20 KB on quality alone, so the tool reduces the dimensions rather than hand you a blocky image. If you need the dimensions kept exactly as you set them, untick Let the tool adjust width and height, and the tool will tell you plainly if the target then becomes unreachable.
JPG and WebP have a quality setting, so the file size can be tuned in small steps. PNG is lossless and has no quality dial, so its size can only be changed by resizing. Choose JPG for accurate KB targets, which is also the format most upload forms ask for.
You can upload and resize up to 50 images in a single batch. All processing happens in your browser so there are no server limits.
Yes. CodBolt uses high-quality bicubic interpolation (imageSmoothingQuality: high) for smooth, sharp results on every image in the batch.
After all images are processed in your browser, they are bundled into a single ZIP file using JSZip and downloaded in one click. No files are uploaded to any server.
JPG (smallest file size, great for photos), PNG (lossless, supports transparency), or WebP (best compression + quality balance, supported by all modern browsers).
No. All resizing runs entirely in your browser using the HTML5 Canvas API. Your images never leave your device.