Compress Images Without Uploading Them
Shrink JPG, PNG and WebP files with a quality slider or an exact target size in KB. Compression runs in your browser, so photos are never uploaded.
Runs entirely in your browser — nothing is uploaded
PNG is compressed losslessly, so it shrinks far less than JPG or WebP. Convert photos to JPG or WebP for the biggest saving.
Two ways to compress
By quality gives you a slider. Higher keeps more detail, lower makes a smaller file, and the same setting applies to every image in the batch. This is the mode to use when you care how the result looks.
By target size works backwards from a number. You say 200 KB and the tool finds the highest quality that still fits. Use it when something else imposes the limit — an upload form that rejects anything over 2 MB, an email attachment cap, a job application that specifies a maximum.
What quality setting should I use?
For photographs, the honest answer is that 80 is right almost always. The range worth knowing:
- 90 to 100 — visually identical to the original, but the file barely shrinks. Mostly wasted.
- 75 to 85 — the useful range. Typically 60 to 80 percent smaller with no difference anyone notices on a screen.
- 60 to 75 — visible if you look closely at edges and skies. Fine for thumbnails and background images.
- Below 60 — obvious blockiness and smearing. Only for previews, or when a hard size limit leaves no choice.
Why quality does not map neatly to file size
Compression works by discarding detail the eye is bad at noticing, so how much a file shrinks depends entirely on what is in it. A photograph of a blank wall compresses enormously; a photograph of gravel or foliage barely compresses at all, because every pixel genuinely differs from its neighbours.
This is why the target size mode has to encode the image several times and measure the result. There is no formula to shortcut it — the tool narrows the range with each pass until it lands on the best quality that fits.
Resize first, compress second
The single biggest saving usually is not compression at all. A photo straight from a phone is around 4000 pixels wide. Displayed in a 600-pixel column, more than 90 percent of those pixels are thrown away by the browser after being downloaded.
Run the image through the resizer first, down to roughly twice the size it will actually be displayed at, and then compress. The combination routinely turns a 5 MB photo into 150 KB with no visible difference, which no amount of compression alone would achieve.
Compress from the original, every time
JPG and WebP are lossy: each pass permanently discards detail, and the damage accumulates. Compressing an already-compressed file twice does not halve it again — it just degrades it. Keep your originals and always start from them.
PNG is the exception, being lossless. That also means a PNG photograph will never shrink much no matter what you do, because the format is obliged to reproduce every pixel exactly. If it is a photograph, convert it to JPG or WebP.
Nothing is uploaded
Your images are decoded, redrawn and re-encoded by your own browser. No file is transmitted, no copy is stored, and there is no queue or daily limit to hit — the work happens on your processor, which is also why a large batch runs at the speed of your machine rather than your connection.
Frequently asked questions
How small can I make an image without it looking bad?
For photographs, quality 75 to 85 usually cuts the file by 60 to 80 percent with no difference most people can see. Below about 60 you start to notice smearing around edges and blotches in smooth areas such as skies. Screenshots and graphics with flat colour behave differently and are better served by PNG or a resize.
What does the target size option actually do?
It searches for the highest quality setting that still fits under the size you asked for. There is no formula linking quality to file size — it depends entirely on the image — so the tool encodes the picture several times and narrows in on the answer. If even the lowest quality overshoots, it tells you rather than pretending it succeeded.
Why did my PNG get bigger instead of smaller?
PNG uses lossless compression, so re-encoding a well-optimised PNG can add a little rather than remove it. PNG is also the wrong format for photographs. If the image is a photo, convert it to JPG or WebP and it will shrink dramatically.
Is quality lost every time I compress?
Yes, for JPG and WebP. Each pass throws away detail permanently, and the losses accumulate, so repeatedly compressing the same file visibly degrades it. Always compress from your original rather than from a file that has already been through the process.
Should I use JPG or WebP?
WebP files are typically 25 to 35 percent smaller than a JPG of matching quality, and every current browser supports it. Choose WebP for your own website. Choose JPG when the file is going to someone else, into an old system, or to a print shop, since compatibility is still broader.
Are my photos uploaded anywhere?
No. The image is decoded, redrawn and re-encoded by your own browser, and nothing is transmitted. You can confirm it by opening your browser network tab while compressing, or by disconnecting from the internet — the tool keeps working.