How to compress an image to 100 KB

By Haris Asif · Published September 29, 2026

Use 100 KB as a maximum file-size limit, then check the dimensions and format separately. SizeKit lets you set all three without uploading your photo to a server.

Open the tool with a 100 KB limit

Compress your photo step by step

Read the destination’s requirements. Check its maximum file size, accepted formats and required pixel dimensions. If it gives a minimum file size, note that too.
Choose your photo. Open a JPG, PNG or WebP file in SizeKit. The input limit is 20 MB and 40 megapixels. An iPhone HEIC photo needs conversion before this tool can open it.
Select 100 KB. The limit applies to your output. It does not mean that your starting photo must already be smaller than 100 KB.
Set the dimensions. Enter the width or height your form requests. Keep proportions enabled to avoid stretching. If the form requires a different shape, crop the photo in a separate editor first.
Choose a supported format. Use JPG when the form requests JPEG. Choose WebP only if the destination accepts it. A PNG input is converted to your chosen output format.
Resize, preview and download. Inspect the result for readable text, clear facial features and intact signature strokes. Submit the downloaded file rather than the original.

A real SizeKit example

The built-in sample photo started at 233.2 KB and 1600 × 1067 pixels. With the width set to 800 pixels, proportions locked and a 100 KB maximum, a tested JPG output was 94.0 KB at 800 × 534 pixels.

This is an example, not a promised result for every image. Fine textures, large dimensions and browser encoders affect how small the output can be. You can use “Try a sample” on the tool to check the workflow before choosing your own file.

Why is the result smaller than exactly 100 KB?

The setting is an upper limit. SizeKit searches for an encoding quality that fits within it; it does not add unnecessary data to make a file exactly 100 KB. It counts 1 KB as 1,000 bytes, so the 100 KB setting allows up to 100,000 bytes. Some operating systems report file sizes using a different unit convention.

If a form requires a range such as 50–100 KB, a file below 50 KB may still be rejected. SizeKit does not enforce a minimum. Check the final file against both limits.

What if the photo cannot fit?

SizeKit keeps the dimensions you chose. If even a low-quality export exceeds your size limit, it reports an error instead of silently shrinking the image. Reduce the pixel dimensions only if the form allows it. If the dimensions are mandatory, check whether you can crop unnecessary background first or use another accepted format.

If the file fits but the form still rejects it, check the actual format, aspect ratio, minimum dimensions and minimum file size. Renaming a filename from .webp to .jpg does not convert it.

Can I use 50 KB or 200 KB instead?

Yes. Choose a preset or type a custom maximum in the same tool. A lower limit can remove more detail. Use the largest limit the destination permits and always check the downloaded result.