Make an image file smaller: resize or lower JPEG quality?
Choose the setting that solves your upload limit, compare small text and detail, and keep an original copy before reducing image size.
In brief
If an image is far wider than its intended display, reduce dimensions first. If the dimensions are needed but the file is too large, compare a modest quality change. The best order depends on whether you must preserve fine text, detail or a required width.
File size and pixel dimensions are different limits. A form that asks for a maximum width will not be satisfied just by lowering JPEG quality.
This guide uses the linked product documentation. Worked scenarios explain how to check your own result; they are not measurements of your device.
Read the actual requirement
A profile image, a product photo and a scanned receipt have different needs. Start with the destination’s width, height, format and file-size limits. Do not use one generic export setting for every image.
For a receipt, readable amounts and dates matter more than decorative texture. For a banner, its required proportions matter. Decide what information must remain visible before reducing the file.
Compare dimensions and compression separately
Create one copy with reduced dimensions and another with the needed dimensions but lower JPEG quality. Compare file size and visible detail. This helps show which control solves the problem without unnecessarily degrading the result.
Inspect text, edges and areas with fine detail. If a letter or number becomes unclear, use a better-quality export or a format better suited to text. A file that fits the limit but cannot be read has failed the task.
Make the last export from the original
Once you choose settings, export from the original rather than a chain of previous compressed versions. Open the final file and test the destination instead of relying only on a preview inside the converter.
Use the local image converter for supported exports, and verify the actual downloaded file size. A file extension or quality slider does not by itself guarantee a particular number of bytes.
Worked example: meet a 1200-pixel width limit
Suppose the original is 4000 × 3000 pixels and the form allows a maximum width of 1200 pixels. Keep the aspect ratio: 3000 × 1200 ÷ 4000 = 900, so export 1200 × 900. That leaves 9% of the original pixel count. It does not promise a 91% smaller file: format, detail and encoder settings still affect bytes.
In Image Resizer, set width to 1200 with the ratio preserved. If the downloaded copy passes the dimension check but exceeds the byte limit, open the original in Image Compressor and set the same maximum width before adjusting quality or a target size. Read the actual result. A target-size warning means the requested limit was not achieved; do not rename the file and assume it passed.
For an ID, receipt or coursework screenshot, inspect the smallest required text after downloading. If it is no longer readable at the required dimensions, obtain a clearer original or ask the recipient for an accepted alternative. More aggressive compression cannot recover missing detail.
| Form requirement | First adjustment | What proves success |
|---|---|---|
| Maximum width or height | Resize while keeping the ratio | Downloaded width and height meet the rule |
| Maximum file size only | Compare encoding quality at useful dimensions | Actual byte size and readable detail |
| Exact width and height | Crop to the ratio, then resize | Both dimensions match without stretching |
Documentation for these steps: MDN — canvas image export ↗
Tools for this task
Before you act
Lossy exports can remove detail permanently from that copy. Repeatedly saving a compressed result is not the same as making fresh exports from the original.
What to do next
- Read whether the destination limits file size, dimensions or both.
- Save the original and choose the smallest dimensions that still suit the task.
- Export a copy, then compare quality settings if the file remains too large.
- Check text and important detail at the actual viewing size before uploading.
