A target file size is a goal, not a guaranteed output
Two images with identical pixel dimensions can compress to very different sizes. Texture, detail, transparency, image format, encoder behavior, and quality settings all affect the result. Reaching exactly 100 KB or 200 KB may not be possible without a noticeable quality or dimension trade-off.
Check whether the destination means decimal kilobytes or kibibytes, and confirm its current upload limit. Do not assume that a size target accepted by one website or email provider is accepted by another.
Choose what you are willing to change
If the image is larger than its display needs, reducing pixel dimensions can reduce file size. For photographs, a lossy format such as JPEG or WebP may be smaller, while diagrams or transparent artwork may need a format that preserves crisp edges or alpha transparency.
Lower lossy quality can reduce size but may introduce visible artifacts. Keep a copy of the original and check the result at the size it will actually be viewed.
Work toward the target with Pixuna
The Format Optimizer lets you choose JPEG, WebP, or AVIF and set a quality value. Its Auto mode selects a format and quality based on the image and browser; images wider or taller than 2,000 pixels are scaled down. It does not accept a target file size, and browser support for an output format can vary.
The Image Compressor has no quality or target-size control: it scales images wider than 1,200 pixels and exports JPEG at a fixed quality. The Image Resizer can change dimensions while preserving the aspect ratio when that option is enabled.
Use a measured, repeatable workflow
Start with the original image and a reasonable output format. Export once, inspect the resulting file size and visual quality, then adjust the format, quality, or dimensions and export again from the original. Re-encoding the latest lossy output repeatedly can compound quality loss.
If the result is still above the target, decide whether smaller dimensions or lower quality are acceptable. If either would harm the image, keep a larger file or choose another delivery method rather than promising an exact 100 KB or 200 KB output.
For email and upload forms
Email providers and upload forms set their own attachment or file-size limits, and some apply limits to the total message rather than one image. Check the limit shown by the service you are sending to, then leave room for any other attachments. This guide and Pixuna tools cannot guarantee acceptance by a third-party service.
Pixuna processes these image operations in your browser.