How to use the target file size compressor
- Choose or drop images. You can add several at once.
- Enter the target size as a number and a unit (KB or MB). Common values are in the list. Also set the output format and the quality floor.
- Press Compress to target, then save each result or save everything as a ZIP.
How it fits a target size
JPG and WebP are saved with a quality value, and lower quality gives a smaller file. But how many KB you get at a given quality differs for each photo, so matching a target by hand means saving many times. This free tool does that repetition for you. It saves at a middle quality, lowers the quality if the file is too big and raises it if the file is smaller, halving the range each time. This binary search finds the best quality under the target in about seven tries.
Some large photos cannot reach the target however low the quality goes. Pushing quality too low breaks the picture badly, so this tool sets a quality floor and does not go below it. It reduces the width and height instead. File size shrinks almost in proportion to the number of pixels, so the tool calculates a size from the ratio between the target and the current size and adjusts step by step.
Results are saved as JPG or WebP. A PNG original is converted the same way, and transparent areas become white in JPG. Files already under the target are left alone, because re-saving would only lower quality. The image is redrawn, so the original location and camera data do not stay in the result.
Ideas and limits
Online applications and document uploads often limit photos to something like 200 KB or attachments to 1 MB. Enter that number as the target and you get the sharpest photo that fits. Shrinking ahead of time saves you from rushing at the last minute.
It also helps with email attachment limits and upload limits on boards and second-hand apps. Adding many photos, shrinking them to the same target and saving a ZIP lets you handle dozens at once.
Images on a blog or shop load faster when they are small. Choosing WebP often gives a smaller file than JPG at the same quality. Some environments cannot open WebP, so check that the place you upload to supports it.
Screenshots with lots of text can look smeared around the letters when shrunk to JPG. For these, set the quality floor to High and turn on shrinking, so size is reduced instead of quality and the text stays sharper.
A target that is too small makes the photo visibly mushy. Trying to shrink a 5 MB original to 50 KB needs a big size reduction and ends up close to a tiny thumbnail. Check the reduced size in the result list and raise the target a bit if needed.
Even with the same quality value, browsers create JPG differently, so the result size can differ slightly. This tool only fits the file size and has no color correction or cropping. Use other tools together if you need to change the aspect ratio.
Tips for good results
- Set the target about 5 percent under the limit to avoid failures from unit differences.
- Use JPG or WebP for photos, and a High quality floor for text-heavy screenshots.
- With shrinking on, most files reach the target.
- Always check the reduced dimensions in the result list.
- Process many files at once and save a ZIP.
FAQ
Does it hit the target exactly?
It finds the best-looking result at or under the target. It narrows the quality value with a binary search of about seven steps, so it usually stops at 90 to 100 percent of the target. KB means 1,024 bytes, and operating systems display sizes slightly differently, so you may see a 1 to 2 percent difference.
What if lowering quality alone cannot reach the target?
If "also shrink the dimensions" is on, it reduces the width and height step by step until it fits. If it is off, the size stays and quality drops to the minimum, and if that still fails the row says "Could not reach target". Then raise the target or turn on shrinking.
Can I reduce PNG files too?
You can add them, but the result is saved as JPG or WebP. PNG cannot be tuned with a quality value, so conversion is used. A PNG with a transparent background gets a white background in JPG, so choose WebP if you need transparency.
I do not see the WebP option.
If your browser cannot save WebP, the option is hidden. Some Safari versions are like this. Choose JPG in that case.
What happens to the location data in the original photo?
The image is redrawn and saved, so the GPS location and camera data (EXIF) of the original are not in the result. It also helps when you want to remove location data before uploading a photo.
Notes & limitations
Images are processed only in the browser and are not sent to a server. Reducing file size always lowers quality, so keep your originals. Check the format and size conditions set by the place you submit to.