Online tools Australia
Compress Image Online
Large images slow web pages, fill inboxes and fail upload limits. This tool re-encodes your images at a lower quality and, if you want, a smaller size, and shows exactly how much smaller each file becomes. Your pictures stay on your device throughout. Built for Australian users, with nothing sent to a server.
Free, no signup Runs in your browser
70 to 80 is a good starting point for photos.
Images larger than this are scaled down. Leave 0 to keep the size.
Result
—Files
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Original size
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New size
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Saved
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Your files
How do I reduce the file size of an image?
Lower the quality, shrink the dimensions, or switch to a more efficient format. A phone photo of 4 to 5 MB typically falls to under 1 MB at 75 to 80% quality and 2,000 pixels wide, with no visible difference on screen. Choose WebP for the smallest files where it is supported and JPG for the widest compatibility.
What to set
For a web page or email, a longest side of 1,600 to 2,000 pixels and quality of 75 to 80% is a sensible default. For printing, keep more pixels: a photo printed at A4 needs about 3,500 pixels on the long side for a sharp result.
If you need a precise file size, such as under 200 KB for a form, lower the quality or the dimension a little at a time and watch the size shown.
PNG and transparency
PNG is lossless, so the quality slider does nothing to it. To shrink a PNG, convert it to WebP or reduce its pixel size. Converting to JPG removes transparency by filling it with white, which this tool does by default.
To change the format only, use the image converter.
How this is calculated
The rule, step by step, so you can check any figure by hand.
each image is drawn onto a canvas, scaled so its longest side is no more than the limit you setthe canvas is encoded at your chosen quality as JPG or WebPif the result is not smaller than the original, the original is keptthe saving is the difference in file size
Most of the saving usually comes from the dimensions, not the quality slider. A 4,000-pixel photo displayed on a web page only ever needs about 1,600 pixels across, and reducing the pixels reduces the file in proportion. Quality settings between 70 and 85 give a large cut in size with little visible loss, while below about 60 compression artefacts begin to show.
A PNG screenshot compresses well to WebP or JPG, while a photo already saved at low quality has little left to remove, which is why the tool keeps the original if re-encoding would not shrink it.
A worked example
A 4.2 MB phone photo, 4,032 × 3,024 pixels, compressed at 75% quality to a 2,000 pixel maximum.
- Original4.2 MB, 4,032 × 3,024
- After scaling to 2,000 wide and 75% qualityabout 0.45 MB
- Savedroughly 89%
A file about a tenth of the size that still looks the same on screen.
Real savings vary by image.
Privacy for Australian users
The images never leave your device, so nothing is stored or shared. If you are preparing photos of customers or staff, working locally is consistent with the Privacy Act 1988, because no copy is made elsewhere.
What it leaves out
Metadata such as location and camera details is dropped. Colour profiles are not carried over, so very colour-critical work should use professional software.
What this calculator does not do
- JPG and WebP output only
- Lossy: keep your originals
- Large images depend on device memory
- Animated images lose their animation
Common questions
How much can I compress an image?
Photos commonly shrink by 70% to 90% with little visible change. Graphics shrink less.
Does compressing reduce quality?
Slightly, for JPG and WebP. Keep the original and compress a copy.
Is my image uploaded?
No. Everything runs in your browser.
What size should a web image be?
Usually no more than 1,600 to 2,000 pixels on the long side, and under 300 KB.
Why did the tool keep my original?
Re-encoding would not have made it smaller, so keeping the original gives the better file.
Where these numbers come from
- MDN — HTMLCanvasElement.toBlob How browsers encode canvas pixels to JPEG, PNG and WebP
- Google — WebP image format How WebP compares with JPEG and PNG
- Office of the Australian Information Commissioner Australia's privacy regulator, for the Privacy Act 1988
Method last reviewed 2026-10-28 This calculator uses fixed rules rather than rates that change, and its method is re-checked against the sources above at least once a year. Out of date? Tell us and we will fix it.
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