How to Reduce a Photo's Size in KB for Online Application Forms

An exam, job or scholarship portal asks for a photo "under 50 KB", and the photo on your phone is 3 MB. The upload button just shows an error. This guide shows how to bring the file down to size in two short steps, and how to do it without making the face blotchy.

The quick answer: resize first, then compress

1. Read the form's instructions and note three things: the file format (usually JPG or JPEG), the allowed size in KB, and the width and height in pixels if they are given.
2. Open the Image Resizer and make the photo smaller in pixels. Enter the width and height from the notice, or about 600 pixels for the longer side if the notice gives none. Choose JPG as the output format, press Resize images and download the result.
3. Open the Image Compressor and add the resized photo. Leave Quality at 80% and press Compress images.
4. Read the new size in the list. If it is still above the limit, lower the quality by 10 and press Compress images again. When it fits, download it.

Both tools run inside your browser. The photo is not uploaded anywhere, which matters for ID photos and certificates.

Why a phone photo is so many KB

The size of a JPG depends mainly on two things: how many pixels it has, and how much fine detail is kept in each part of the picture.

A typical phone photo of 4000 × 3000 pixels holds 12 million pixels. A passport-size photo printed at 35 × 45 mm needs only 413 × 531 pixels at 300 DPI, which is about 220,000 pixels. That is more than fifty times fewer. A portal that shows your photo in a small box on an admit card has no use for the rest.

The Quality slider controls the second thing. Lower quality removes detail that is hard to see, which is where JPG saves most of its space. But on a full-size phone photo it is a weak lever: to squeeze 12 million pixels into 50 KB, the compressor would have to throw away so much that faces turn patchy. The compressor also keeps the width and height of your image as they are (only very large images are scaled down on some phones, with a note). That is why the pixels have to come down first, in the resizer.

A worked example

Say a recruitment form asks for a JPG photo between 20 KB and 50 KB, with no pixel size given. Your photo is 3000 × 4000 pixels (a portrait) and 3.2 MB.

1. In the Image Resizer, choose Pixels, type 600 in Height and leave Width empty. The width is worked out from the photo's own shape, so the result is 450 × 600. That is about 2% of the original pixels.
2. In the Image Compressor, add the 450 × 600 file and compress it at 80%. The list shows the old size, the new size and how much smaller it got.
3. If the new size is above 50 KB, try 70%, then 60%. If it is still too big, go back to the resizer and use 500 instead of 600. Taking away pixels usually looks better than pushing quality very low.
4. If the file is now below the 20 KB minimum, you went too far. Raise the quality, or start again from the original photo with a larger height such as 800.

Your own numbers will differ, because a photo with a busy background (leaves, patterned clothes) needs more bytes than one against a plain wall.

Choosing the quality

• 80%, the default, is a good place to start. Between 70% and 85%, a compressed photo is usually indistinguishable from the original at normal viewing sizes.
• Lower settings save more, but look closely at the face before you upload. As quality drops, smooth areas such as cheeks and a plain background show blocky patches, and edges such as hair and spectacle frames get faint halos.
• Very low settings are rarely worth it for a form photo. If 60% is not enough, reduce the pixels again instead.

After downloading, open the file and zoom in. If it looks fine to you at full size, it will look fine in the portal's small box.

Use JPG for photos, not PNG

Many portals accept only JPG or JPEG files, and a photo saved as PNG is usually several times larger than the same photo as JPG. If your photo is a PNG, set Output format to JPG in the compressor, and it is converted while it is compressed.

PNG compression in this tool works differently: it reduces the number of colours. That works well for screenshots, logos and scanned forms with flat colours, which often shrink by 50 to 80%, but it is the wrong choice for a photo of a face.

Photos from an iPhone are often saved as HEIC, which the compressor cannot open. Convert them to JPG with the Image Converter first (this works in Safari 17 or later), or set your iPhone to Settings › Camera › Formats › Most Compatible so new photos are saved as JPG.

Mistakes to avoid

Compressing the same file again and again. Every JPG save throws away a little more detail. If a result is still too big, go back to the original photo and compress it once at a lower setting.

Stretching the photo to an exact pixel size. If the form asks for, say, 200 × 230 pixels and your photo has a different shape, crop it to that shape first. With Keep aspect ratio switched on, the resizer will not stretch it.

Aiming exactly at the limit. Some websites count a kilobyte as 1,000 bytes and others as 1,024 bytes, so a file your phone shows as "50 KB" can be slightly over on the portal. Stay a few KB below the maximum and above the minimum.

Keeping details you do not need. By default the compressor removes EXIF data, including the GPS location saved by many phones. Only switch on Keep EXIF data if someone has asked for it.

Frequently asked questions

Why did my photo get only a little smaller?

It was probably compressed well already, for example a photo received on WhatsApp. When the result would not be smaller than your file, the tool marks it Original kept and gives you the original back. Reduce the pixels in the resizer instead.

Can I do the same for my signature?

Yes, the same two steps apply, and signature limits are often even smaller. Start with a clean image: the Image Signature Maker turns a photo of your signature on paper into a tidy picture of just the ink.

Will the portal accept the file once it is under the limit?

The size is only one check. The format, the pixel size and what the photo must show are set by the organisation, and they change from one notice to the next. Read the current instructions for your form before you upload.

Wrapping up

Getting a photo under a KB limit is a two-step job: first make it smaller in pixels, then save it as a JPG at a sensible quality. Resize in the Image Resizer, fine-tune the KB in the Image Compressor, and check the face at full size before you upload. Other tools for photos are in the image tools section.