Convert an image from MB to KB
A camera photo is measured in megabytes and an upload form in kilobytes. Type the KB limit, add the photo, and get a copy that fits under it.
- Runs in your browser
- Nothing is uploaded
- No sign-up
- Batch up to 20 images
Drag & drop your image here
or tap to browse · you can also paste from the clipboard
JPG · PNG · WebP · GIF · BMP · AVIF · SVG · up to 50 MB each · up to 20 files
Choose imagesBefore
After
Processed image will appear here.
How to use the MB to KB image converter
Type the size you need in KB and add your photo. The page searches for the highest quality that fits under that limit and scales the picture down only if it must. A megabyte is 1,000 KB, so a 3 MB photo has to lose most of its bytes to meet a limit such as 500 KB.
- Add your photoAny size up to 50 MB. Several at once is fine.
- Type the limit in KB500 is preset. Enter the figure your form or site gives.
- Download the smaller fileIt is just under the limit, with the quality and scale shown.
About this tool
A megabyte is a thousand kilobytes, so a 3 MB photo is 3,000 KB: thirty times over a 100 KB limit. No setting hidden in the file changes that. The only way from MB to KB is to store the picture in fewer bytes, by compressing it harder, giving it fewer pixels, or both.
This page is the Image File Size Reducer set up for that jump. You type the limit in KB and it searches for the highest quality that fits, scaling the picture down only when quality alone cannot get there. The table further down shows what common megabyte sizes are in kilobytes, and how large a photo each one holds.
What you get
- Brings a multi-megabyte photo under any KB limit
- Searches for the highest quality that fits
- Scales the picture down only when it has to
- Keeps the format, or converts to JPG, WebP or PNG
- Batch up to 20 photos and download a ZIP
When to use the MB to KB image converter
A phone photo for a form with a KB limit
Cameras produce files of 3 to 8 MB, and forms commonly cap uploads at 100, 200 or 500 KB.
Attachments that keep bouncing
Mail systems and help desks with small attachment limits accept a photo once it is a few hundred kilobytes.
Pictures for a listing or a profile
Marketplaces and directories show images small, so a file in kilobytes loads faster and looks no different on the page.
Saving space in a shared folder
A set of photos kept for reference, not for printing, takes a fraction of the room at 300 to 500 KB each.
MB to KB conversion, and what each size holds
| Size in MB | In KB (1 MB = 1,000 KB) | Shown by Windows as | A photo that fits at high quality |
|---|---|---|---|
| 0.5 MB | 500 KB | 488 KB | About 1560 × 1170 pixels |
| 1 MB | 1,000 KB | 977 KB | About 2200 × 1650 pixels |
| 2 MB | 2,000 KB | 1,953 KB | About 3090 × 2310 pixels |
| 5 MB | 5,000 KB | 4,883 KB | A 12-megapixel phone photo, with room to spare |
| 10 MB | 10,000 KB | 9,766 KB | A 24-megapixel camera photo, with room to spare |
How it works
The two units differ only by a factor: 1 MB is 1,000 KB in decimal units, or 1,024 KB in the binary units Windows shows. Converting the number is trivial, and converting the file is not. A JPG's size is set by how many pixels it has and how much detail is kept for each one. To bring a file from megabytes down to kilobytes the tool lowers the quality setting first, testing up to eight settings to find the highest that fits.
Quality has a floor below which a picture falls apart, so when even the lowest setting is too big the image is scaled down and the search starts again, for up to four rounds. A 12-megapixel photo aimed at 200 KB comes out both scaled down and at a low quality setting for that reason, and resizing it first gives a cleaner result. The limit you type is treated as 1,000 bytes per kilobyte. A result made for 500 KB is therefore no more than 500,000 bytes, which Windows displays as about 488 KB.
Common problems and how to fix them
- The result looks blocky
- The limit is small for the number of pixels in the photo, so quality was pushed very low. Resize the photo first with the Image Resizer, to about 1600 pixels wide for 500 KB or 1000 for 200 KB, then run it here again.
- Windows shows fewer KB than I typed
- Windows divides by 1,024 and this page counts 1,000 bytes to the kilobyte, so a file made for 500 KB shows as about 488 KB. It is under the limit by either count.
- The file did not get under the limit
- Scaling is switched off, or the limit is too small for the image at any quality. Turn on "Scale the image down if needed", or choose WebP as the output format if the site accepts it.
- I need the size in MB, not KB
- Switch the unit to MB beside the size box. To make a small file larger instead, use the KB to MB Converter.
Frequently asked questions
How many KB is 1 MB?
1,000 KB by the decimal definition used for storage and by macOS, and 1,024 KB by the binary definition that Windows uses. The difference is 2.4%. This page counts 1 KB as 1,000 bytes when it checks a limit, the stricter of the two, so the result passes whichever one your form uses.
How do I convert a photo from MB to KB?
Add it above and type the size you need in KB. The photo is compressed, and scaled down if necessary, until it fits. A file cannot be relabelled from MB to KB; it has to be made smaller.
Can I reduce a 5 MB photo to 100 KB?
Yes, but not at its full size. A 5 MB phone photo has about 12 million pixels, and 100 KB holds roughly 700 × 520 of them at good quality. The tool lowers the quality as far as it can before it scales the picture down, so a photo this large comes out soft. For a cleaner result, resize it to about 800 pixels wide with the Image Resizer first, then bring it under 100 KB here.
Will the photo lose quality?
Some, because that is where the saving comes from. Going from a few megabytes to 500 KB or more is hard to notice. Below about 200 KB a large photo is visibly softer. Compare the before and after previews before you download.
How do I reduce a 2 MB image to 500 KB?
Add it above; 500 KB is already the preset. A 2 MB photo usually reaches 500 KB by quality alone and keeps its pixel dimensions.
Is KB bigger than MB?
No. A megabyte is a thousand times a kilobyte, so 1 MB is larger than 999 KB. When a form says "maximum 500 KB", a 2 MB file is four times too big.
Does the converter change the image format?
Not by default. The format you add is the format you get back. You can choose JPG, WebP or PNG as the output if the site you are uploading to prefers one.