CalculatorImage tool
Compress, resize and convert images in your browser.
Three image jobs need three different choices
A large image does not always need very low quality. Decide the use, pixel dimensions and transparency first, then choose JPG or PNG.
A phone photo for a webpage
- Input
- Original 4000 × 3000; maximum width 1600; output JPG
- Result
- Output about 1600 × 1200; actual file size depends on detail and quality setting
- What it means
- Web display rarely needs the camera’s full dimensions. Resize pixels first, then adjust quality gently.
A logo with transparency
- Input
- Transparent PNG; maximum width 1200; keep PNG output
- Result
- Transparency is retained and pixel dimensions scale proportionally
- What it means
- Do not switch to JPG merely for size because transparency is lost; flat graphics can also stay sharper as PNG.
An 800px-wide screenshot
- Input
- Original width 800; maximum width 1600; output PNG
- Result
- It is not enlarged and remains 800px wide; file size is not guaranteed to fall
- What it means
- Upscaling cannot create detail, and re-encoding unsuitable content or format can even produce a larger file.
How should you use the calculated result?
Processing stays in the current browser; the image is not uploaded to this site. Maximum width only reduces larger images. Pixel count, format, transparency and visual complexity all affect output size.
When should you not use this result directly?
- The tool cannot guarantee a target KB size, recreate missing detail or repair a badly blurred original.
- Very large images consume device memory; unsupported formats, damaged files or files above the page limit may fail.
- Current export focuses on JPG and PNG. Use specialist software for WebP, batches, colour management or full metadata retention.
Continue with the image format and compression guide
The guide starts with photos, transparent logos and screenshots, then explains when to resize first, how to choose JPG or PNG, and why output can grow.
Open the image guide
Technical reference: MDN File API
Rules last checked: 7 Sep 2026. See the Sources page.