Large images slow down pages, get bounced by upload limits, and eat storage. Four things change the file size: the format you pick, the pixel dimensions, the quality setting, and the metadata riding along. They are not close to equal, so the order you pull them matters.
Where these numbers come from
Every figure below was produced by encoding one deterministic 900×600 test photograph through the Canvas toBlob API in Chromium 151.0.7922.34 on 2026-09-02 — the same encode path the Image Converter runs in your browser. Absolute numbers depend on the image; the format comparison guide explains the method in full and lets you download the source files.
1Choose the format first
This is the largest single lever for photographs, and it costs you nothing visible. The test photo is 941 KB as a PNG because PNG is lossless and has to record every grain of sensor noise exactly. The same image at quality 0.8 is 64 KB as JPG and 62 KB as WebP.
| Format | Size | Saved vs PNG |
|---|---|---|
| PNG | 941 KB | — |
| JPG, quality 0.8 | 64 KB | 93% |
| WebP, quality 0.8 | 62 KB | 93% |
If the image needs transparency you cannot use JPG at all, but WebP keeps the alpha channel and is still far smaller than PNG. The one case where PNG is the right answer is flat graphics and screenshots, where lossless is both smaller and cleaner than a lossy format would be.
2Reduce the dimensions — this beats the rule of thumb
The common advice is that file size falls in proportion to pixel count: half the width and half the height means a quarter of the pixels, so expect roughly a quarter of the bytes. The measurements say you do better than that.
| Scale | Dimensions | Pixels remaining | JPG bytes remaining | WebP bytes remaining |
|---|---|---|---|---|
| 100% | 900×600 | 100% | 64 KB (100%) | 62 KB (100%) |
| 75% | 675×450 | 56% | 28 KB (44%) | 15 KB (25%) |
| 50% | 450×300 | 25% | 11 KB (18%) | 5 KB (8%) |
| 25% | 225×150 | 6% | 3 KB (5%) | 2 KB (3%) |
At 75% scale the image keeps 56% of its pixels but only 44% of its JPG bytes. At 50% it keeps a quarter of the pixels and under a fifth of the bytes.
The reason is that downscaling averages neighbouring pixels together, and that averaging destroys exactly the high-frequency noise that is most expensive to encode. You are not only sending fewer pixels — you are sending pixels that compress better. WebP gains even more from this than JPG.
3Lower the quality setting
Quality is the fine adjustment. It moves the file a lot at the top of the scale and much less at the bottom, which is the opposite of how people usually reach for it.
| Quality | JPG | WebP | Change from 0.95 |
|---|---|---|---|
| 0.4 | 16 KB | 9 KB | −92% |
| 0.6 | 31 KB | 23 KB | −85% |
| 0.8 | 64 KB | 62 KB | −68% |
| 0.95 | 202 KB | 175 KB | — |
Dropping from 0.95 to 0.8 removes 68% of the file for a difference most people cannot see. Going further to 0.6 removes 85% in total, and by 0.4 the encoder is visibly smoothing detail away. Around 0.8 is the usual sweet spot; below 0.6 you should be looking at the result rather than trusting the number.
4Drop embedded metadata
Camera and phone photos carry an EXIF block holding camera settings, timestamps, and sometimes GPS coordinates. It is worth removing — but be clear about why. A typical EXIF block is a few kilobytes against a photo measured in hundreds, so it will not rescue an oversized file. Converting through BravoConvert re-encodes pixels through Canvas and does not carry the source EXIF block into the output, which matters more for privacy than for size.
Stacking the levers
Applied together on the same source image, the first two levers alone account for almost the entire reduction:
941 KB down to 5 KB — a 99% reduction, without ever moving the quality slider below 0.8.
Recipes
WebP at quality 0.8, resized to the width the page actually renders. Sending a 4000px-wide photo into a 800px slot wastes most of the file.
Resize first, then lower quality only if you are still over. Resizing preserves apparent sharpness better than heavy compression at full size does.
WebP if the destination accepts it, PNG otherwise. Never JPG — it cannot store transparent pixels and will fill them with a solid colour.
JPG at 0.8 resized to around 1600px on the long edge. Universally readable and comfortably under typical attachment limits.
Start with the Image Converter for format and quality, or the Image Editor to resize first. Both run entirely in your browser, so the file never leaves your device.