Resize images for an upload limit: dimensions, format and quality
An upload form can limit both pixels and file size. Treat those as separate requirements: choose the shape and dimensions first, then adjust the format and compression while inspecting the result.
Start with the required dimensions
Check whether the destination asks for exact dimensions, a maximum edge length, or a particular aspect ratio. In the Image Resizer & Converter, keep proportions enabled to avoid stretching. When both width and height are entered with proportions enabled, width takes priority.
Example: a 4:3 photograph
A 4000 × 3000 image resized to 1200 pixels wide becomes 1200 × 900. If the destination requires a square, proportional resizing alone cannot create that shape. Use a deliberate crop or padding workflow instead.
The Aspect Ratio & Resize Calculator can plan fit padding and centered crop geometry before you change a file. Use Image Crop & Rotate when the subject needs a particular crop rather than an automatic centered one.
Choose JPG, PNG or WebP for the content
- JPG: a useful option for photographs. It does not preserve transparent areas; choose the background color that should fill them.
- PNG: preserves transparency without lossy quality changes. It can be suitable for graphics, but converting a compressed photo to PNG may increase its size.
- WebP: offers transparency and adjustable quality in this converter. Check that the destination accepts it.
See the MDN image format guide for format characteristics. The correct choice depends on the content and the application receiving it.
For HEIC or HEIF photographs, choose JPG, PNG or WebP. The converter exports the primary still image; it does not preserve Live Photo motion, depth data or the original camera metadata.
Use a size target with realistic bounds
- Set the dimensions and output format.
- Enter the destination’s file-size target, such as 100 KB.
- For JPG or WebP, set a quality ceiling and a minimum quality.
- Enable smaller dimensions only when that tradeoff is acceptable.
- Process the image and read its actual size, dimensions and target badge.
In this tool, 1 KB means 1,024 bytes. The destination may label units differently, so allow room below a strict limit. PNG does not use the JPG/WebP quality slider; smaller dimensions are the available size-reduction method here. An unmet target is labeled rather than hidden.
Compare the output before downloading
Look at edges, fine text, skin tones and transparent areas. If the result has distracting artifacts, raise the minimum quality or choose smaller dimensions rather than accepting a poor full-size version.
Download one result first and test it in the receiving application. Once it works, prepare the remaining images with consistent settings. Keep originals when you need camera metadata or future edits. Resizing or converting a GIF produces a still frame; use the GIF tools for animation.
Questions & answers
Why did I miss the file-size target?
Your minimum quality or dimensions may leave too little room to reduce size. Try a suitable format, lower the minimum quality, or permit smaller dimensions, then inspect the result.
Does resizing to a square stretch my photo?
Forcing a different aspect ratio can stretch it. Keep proportions and crop or pad deliberately when the required shape differs from the original.
Why did PNG make my photo larger?
PNG uses a different compression approach and may need more bytes for photographic detail than an already compressed JPG. Compare measured outputs.
Will conversion keep my camera metadata?
Canvas conversions do not preserve original camera metadata. The unchanged-original path retains the source file; keep your originals when metadata matters.
Ready to try it?
Start with Image Resizer & Converter, or choose another practical guide.