How to reduce photo size in KB.

A photo’s size in KB depends on three things: how many pixels it has, how hard it’s compressed, and its file format. To get a photo under a limit like 50 KB or 100 KB, save it as a JPG and lower the quality until it fits. If it still doesn’t fit at a quality that looks fine, make it fewer pixels wide and try again. Start with quality, because cutting pixels throws away more detail.

The image compressor does both steps for you. Type the size in KB you need, and it finds the highest quality that fits. It only shrinks the picture if even low quality is too big. It runs on your phone or computer, and the photo isn’t uploaded.

What decides a photo’s size in KB

Pixels. Google’s web.dev guide puts it plainly: the more pixels an image has, the larger its file. A 12-megapixel phone photo is about 4000 × 3000 pixels, or 12 million pixels. Halve the width and the height to 2000 × 1500 and you have 3 million, a quarter as many. Before compression, every pixel takes a few bytes, so pixel count sets the starting size.

Quality. JPG uses lossy compression: it throws away detail you’re unlikely to notice to make the file smaller. The quality setting, usually a number from 1 to 100, controls how much. Lower numbers mean smaller files and more visible blur and blockiness. Google’s guide gives no single right number. It says to try several quality levels and pick the best trade-off for that photo.

Format. For photos, web.dev recommends JPG (or the newer WebP and AVIF). PNG keeps every detail, but web.dev notes that it costs a much larger file. A screenshot or scanned document saved as PNG often shrinks a lot just by saving it as a JPG instead.

Change	What it does to the file	What you give up
Lower JPG quality	Smaller, often by a lot at first	Fine detail, then visible blocks at low settings
Fewer pixels	Smaller, roughly in step with the pixel count	Sharpness when the photo is zoomed or printed
PNG to JPG	Usually much smaller for photos and scans	Transparency (it turns solid), and lossless detail

How to reduce photo size in KB, step by step

1. Read the limit. Note the maximum (and any minimum) in KB, and any pixel size or format the form asks for.
2. Open the image compressor and choose the target-size mode.
3. Type the limit in KB. Leave a few KB of room, for example 95 for a 100 KB limit.
4. Add the photo. The tool tries JPG quality from 92 down to 40 at full size. If the photo still doesn’t fit at 40, it shrinks the width and height, keeping the shape, until it does.
5. Check the result. The tool shows the old and new size and the new pixel size. Open the file and zoom in on faces and text before you upload it.
6. Download the new file. Your original stays as it was.

For common limits there are one-step pages: resize an image to 20 KB, compress to 50 KB and compress to 100 KB. If the form gives exact pixels, such as 200 × 230, use resize image first, then compress. For a signature, resize signature handles the pixels and the KB together.

If your photo is HEIC, convert it with HEIC to JPG first.

Photo MB to KB: how much smaller can it get?

1 MB is 1,024 KB, so taking a 3 MB photo to 100 KB means making it about 30 times smaller. Quality alone rarely gets that far on a full-size phone photo while still looking good. Expect the pixel size to drop too.

That’s usually fine for a form. If the form lists a pixel size, that’s all the detail it needs. It’s not fine for something you’ll print or crop later, so keep the original.

Small targets like 20 KB almost always mean a small photo. If the form also sets a minimum pixel size, check that the result still meets it.

Resize a photo in Samsung Gallery

Galaxy phones can shrink a photo without another app. Samsung says the feature needs Android 10 or later and may not be on every model.

Before you start: Samsung warns that on Android 11, saving the edit overwrites the original photo instead of making a new one. Use Save copy in step 6 so the full-size original stays. Samsung says you can undo a saved edit by reverting it in the editor, but a copy is the safer route.

1. Open the Gallery app and select the photo.
2. Tap the Edit icon at the bottom of the screen.
3. Tap More options (the three vertical dots) at the top right.
4. Select Resize.
5. Choose a percentage under Resize image, then tap Done.
6. To keep the original, tap More options again and select Save copy. Otherwise, tap Save.

The new file size shows in the photo’s details. Samsung’s resize only goes by percentage and can’t make a photo larger than the original. It also doesn’t let you type a target in KB, so you may need a couple of tries to land under a limit.

Doesn’t compressing ruin the photo?

Some detail is always lost with JPG compression. Whether you can see it depends on how far you go and on the photo. Google’s guide encourages lowering the quality, and says to try a few levels to find the best trade-off. Faces, text and fine patterns show damage first, so zoom in on those.

Every time a JPG is saved again, it loses a little more. Always start from the original photo, not from a copy you’ve already compressed.

A photo can also carry hidden details, such as where it was taken, and not every app removes them when it shrinks the file. To check, open it in the EXIF viewer. To strip the location without lowering the quality, use remove photo metadata.

Questions

How do I reduce a photo’s size in KB on my phone?

Open the image compressor in your phone’s browser, choose the target-size mode, type the limit in KB and add the photo. On a Galaxy phone, you can also use Resize in the Gallery editor and save a copy.

Is 1 KB 1,000 or 1,024 bytes?

Both are in use. Most phones and forms don’t say which they mean. The compressor counts 1 KB as 1,024 bytes. Aim a few KB under the limit and you’re safe either way.

Why is my photo still too big after compressing?

It has too many pixels for the target. Lower the pixel size with resize image, or use the compressor’s target-size mode, which lowers it for you.

Should I change the pixels or the quality?

Quality first, down to where it still looks fine. Then pixels. If the form gives exact pixels, set those first.

Will reducing the size in KB change the photo’s dimensions?

Lowering the quality doesn’t change the dimensions. Hitting a small target like 20 KB usually does. The compressor shows the new width and height so you can check.

Can I make a photo bigger in KB?

Not with Samsung’s resize, which only makes photos smaller. If a form sets a minimum size in KB, resize signature lands the file between the minimum and maximum you type.