Will the result be exactly the KB value I enter?

Not necessarily. The tool tries to produce a result at or below the target, but browser encoders expose quality and dimensions rather than an exact byte control. The actual output size and target status are always shown.

Does KB mean 1,000 or 1,024 bytes here?

The input is labeled KiB and uses the binary definition: 1 KiB equals 1,024 bytes. The page targets the common search phrase Resize Image in KB while stating the measurement explicitly.

Why can PNG miss a small target?

PNG is lossless and does not have a meaningful quality slider. The tool applies OxiPNG optimization once at each tested dimension and then reduces dimensions. Switching to JPG or WebP can reach much smaller targets, but transparency may change with JPG.

Which input and output formats are supported?

The tool accepts JPEG, PNG, and WebP and can export JPG, PNG, or WebP. When exporting JPG, transparent pixels are filled with white. If an accepted input contains animation, the output is static and the animation is not preserved.

Is my image uploaded?

No. The image stays in your browser. A background worker performs decoding and encoding locally, and the output is exposed only as a local download.

Resize Image in KB Online - Target Image File Size

Reduce a JPEG, PNG, or WebP image toward a target file size while keeping the largest practical dimensions. Processing stays in your browser.

Choose one image

JPEG, PNG, or WebP; up to 25 MiB, 40 megapixels, and 12,000 pixels per side. Animated inputs produce a static result; animation is not preserved.

Choose image

Target settings

Target file size

KiB

Enter a whole number from 1 to 20,480 KiB. This tool uses 1 KiB = 1,024 bytes; an exact final size is not guaranteed.Output format

JPG

The tool searches a bounded quality range, then reduces dimensions only when quality alone cannot meet the target.

Reduce an image to a target KB size

Resize Image in KB combines bounded JPG or WebP quality search with proportional dimension reduction. It reports the actual byte result instead of promising an exact size that browser encoders may not be able to produce.

How target-size search works

If the source is already under the target and the format is unchanged, the original file is kept without re-encoding.
For JPG and WebP, the browser tests a bounded quality range and keeps the highest quality that fits at the largest dimensions.
If minimum quality is still too large, dimensions are reduced proportionally and the search repeats without upscaling.
If the target remains impossible, the tool clearly labels the miss and returns only a result that is genuinely smaller than the source.

Why an exact KB value is not guaranteed

Encoded size depends on image detail, noise, transparency, format, and the browser encoder. PNG is lossless and may stay large even after optimization. For aggressive targets, JPG or WebP usually gives the browser more room to reduce bytes.

Common target-size tasks

Reduce a profile photo or document image for a form with a KB upload limit.
Create a smaller attachment while seeing the real output size before downloading.
Prepare JPG, PNG, or WebP assets with a practical file-size budget.
Process personal or sensitive images without sending them to a conversion server.

Browser-local image processing

Decoding, Canvas rendering, quality search, OxiPNG optimization, and downloads happen locally in your browser. BaseToolbox does not upload or store your image.

Related image tools

Resize Image by Pixels Image Compressor Image Converter

Resize Image in KB FAQ

Will the result be exactly the KB value I enter?: Not necessarily. The tool tries to produce a result at or below the target, but browser encoders expose quality and dimensions rather than an exact byte control. The actual output size and target status are always shown.
Does KB mean 1,000 or 1,024 bytes here?: The input is labeled KiB and uses the binary definition: 1 KiB equals 1,024 bytes. The page targets the common search phrase Resize Image in KB while stating the measurement explicitly.
Why can PNG miss a small target?: PNG is lossless and does not have a meaningful quality slider. The tool applies OxiPNG optimization once at each tested dimension and then reduces dimensions. Switching to JPG or WebP can reach much smaller targets, but transparency may change with JPG.
Which input and output formats are supported?: The tool accepts JPEG, PNG, and WebP and can export JPG, PNG, or WebP. When exporting JPG, transparent pixels are filled with white. If an accepted input contains animation, the output is static and the animation is not preserved.
Is my image uploaded?: No. The image stays in your browser. A background worker performs decoding and encoding locally, and the output is exposed only as a local download.