How to Compress an Image to a Specific File Size (100KB, 200KB, 500KB)

A visa application portal says photos must be under 100KB. A job application form caps uploads at 200KB. An insurance claim system refuses files above 500KB. These limits are everywhere, and a phone camera that shoots 8–12 MB JPGs does not care about any of them. Here is how to hit an exact target size without sacrificing more quality than necessary.

Why portals enforce strict file size limits

Government and institutional systems are often built on infrastructure from a decade ago. File size limits keep their databases from filling up, prevent slow uploads on poor connections, and set a ceiling on storage costs. The limits are not arbitrary — they reflect the original design assumptions of the system — but they collide with modern smartphone cameras that produce files ten to a hundred times larger than those assumptions anticipated.

The result is a practical problem: you have a perfectly good photo, a form that needs it, and a size requirement that the photo does not meet. You need a way to reduce the file size to a specific ceiling without running it through desktop software you may not own.

How to compress an image to a specific KB target

The Compress Image tool on keptlocal has a Target size field that lets you set an exact ceiling in kilobytes. Everything runs in your browser — your image is never uploaded anywhere.

1. Open the Compress Image tool.
2. Drop your JPG, PNG, or WebP image into the drop zone.
3. In the Target size field, type the maximum file size in KB — for example 100 for a 100KB limit, or 200 for a 200KB limit.
4. Click Compress. The tool reduces quality automatically until the output falls below your target.
5. Click Save to download the compressed file.

The before and after file sizes are shown next to each image so you can confirm the result meets the requirement before downloading. If you need to compress multiple images to the same target, drop them all at once — each is compressed individually to the same ceiling.

Compress image to 100KB

100KB is one of the most common limits you will encounter — it appears on visa and passport photo uploads, government identity verification portals, and some HR systems. A typical smartphone JPG shot at 12 MP is 3–6 MB, so you are looking at a 97–98% file size reduction.

At 100KB, a photo that was shot at 12 MP will typically be compressed to somewhere between 1–2 MP effective resolution, depending on the content. Faces, documents, and solid-colour backgrounds compress well and look acceptable at 100KB. Highly detailed scenes (dense foliage, fabric texture, complex backgrounds) will show more compression artefacts.

A practical tip for passport and visa photos specifically: before compressing, crop the image to the required framing (typically head and shoulders, with the face centred). A tightly cropped image needs less data to represent the same level of face detail, so it reaches 100KB at a higher effective quality than a full-frame shot compressed to the same size. Use the Crop Image tool first, then compress to the target.

Compress image to 200KB

200KB is a more generous limit — common on job application portals, tenancy application forms, and document submission systems that expect scanned pages rather than professional photographs. At 200KB, a 12 MP photo can retain noticeably better quality than at 100KB, and the result is usually acceptable for any identification or documentation purpose.

For scanned document pages (utility bills, bank statements, ID cards), 200KB is typically enough to keep text readable and logos recognisable. If you are scanning at high DPI, consider reducing the scan resolution first — a document scanned at 150 DPI is usually sharper-looking at 200KB than the same document scanned at 600 DPI and aggressively compressed down to the same file size.

Compress image to 50KB

50KB is a strict limit that you will mostly see on older government portals and systems with legacy infrastructure. At 50KB, visible compression artefacts are almost inevitable on complex photographic content. The best strategy is to combine compression with dimension reduction: resize the image to roughly 400–600 pixels wide first using the Resize Image tool, then compress to 50KB. A smaller image needs less data to represent the same number of pixels, so the quality at 50KB is meaningfully better than compressing a full-resolution photo to the same ceiling.

Understanding the quality-size trade-off

JPEG compression works by discarding fine detail that the human eye is least sensitive to — high-frequency texture, subtle colour variation, and sharp edges in complex regions. At high quality settings (85%+), the discarded detail is virtually undetectable at normal viewing sizes. As quality drops, the artefacts become visible first in regions with sharp colour transitions (text on a background, a sky meeting a roofline) and in fine texture.

The relationship between quality and file size is not linear. Going from 85% to 75% quality typically halves the file size while producing very little visible degradation. Going from 75% to 55% halves it again with more noticeable artefacts. Going below 50% compresses aggressively — the file gets very small but the image looks heavily processed.

When you set a target size, the compression tool iterates through quality levels to find the highest quality that gets the file under your ceiling. You always get the best possible quality for the target size, rather than applying a fixed level and hoping it lands in range.

PNG images and size targets

PNG is a lossless format — it stores every pixel exactly, which means there is no "quality" dial to turn in the same sense as JPEG. Compressing a PNG to a specific size target works differently: the tool reduces the image dimensions until the file fits under the ceiling. A 3000 × 2000 PNG may need to be scaled down to 800 × 533 to fit within 100KB, depending on the image content.

If you need both a small file size and full resolution for a PNG, the practical answer is to convert it to JPG or WebP first. Both formats achieve much smaller file sizes at the same visual resolution. Use the Convert Image tool to convert PNG to JPG, then compress to your target size.

Checking the result before submitting

Once you have the compressed file, verify the file size before uploading to the portal. On Windows, right-click the file and choose Properties — the size is shown in both bytes and KB. On Mac, select the file and press Cmd+I — the size appears under "Size." Make sure the figure shown is below the portal's limit, bearing in mind that some portals use 1 KB = 1000 bytes while others use 1 KB = 1024 bytes. The difference matters at tight limits like 100KB — a 102,000-byte file is under 100KB at 1000 bytes/KB but over at 1024 bytes/KB. To be safe, aim for about 5% under the stated limit.