Batch Image Converter
How to Use
📖 Tool Introduction
Marketing wants twenty JPGs, development needs an ICO icon, and the print shop only accepts BMP. When the same batch of assets has to satisfy different channels, saving each file one at a time gets old fast. This tool converts a whole batch to a single format in one pass, optionally resizing and renaming along the way, then bundles the results into a ZIP.
Everything happens in the browser. Images are never uploaded, so company assets and unreleased product shots are safe to process. Pick the files, set the format and quality, press convert, and watch the progress bar and per-file status update.
Beyond format, it handles dimensions: cap the longest side or scale proportionally by width, which removes a step when preparing listing images or trimming upload size. Naming can keep original filenames, use plain sequence numbers, or combine a prefix with a sequence.
WEBP and JPEG are lossy, so the quality slider is your trade-off between size and detail. PNG and BMP are lossless and suit assets that will be edited again or sent to print.
✨ Features
- Handles up to 60 images per batch, with drag-and-drop instead of file-by-file picking.
- Exports PNG, JPEG, WEBP, BMP and ICO, covering web, print and icon use.
- Resize options: keep original, cap the longest side, or scale by width, always preserving aspect ratio.
- Quality slider for lossy formats to balance file size against detail.
- Three naming rules: keep original names, pure sequence, or prefix plus sequence.
- Bundle everything into a single ZIP, optionally without a subfolder.
- Per-file status in the list: pending, done or failed, with the failure reason shown.
- Live progress bar so large batches never feel like they have stalled.
- Preview pane shows the first result next to source and output dimensions and sizes.
- Fully client-side conversion; images never leave your machine.
- ICO output is capped at 256px to match the icon format limit.
- JPEG conversion fills white so transparent areas do not turn black.
🚀 How to Use
- Press choose images, or drag files into the dashed area; multiple files at once is fine.
- Pick a target format from the dropdown.
- Optionally adjust quality, resize mode and the naming rule.
- Press convert and wait for the progress bar; each file shows its own result.
- Press download results to save a ZIP, or untick the option to download individually.
⚠️ Notes
- JPEG has no alpha：Transparent areas become white when converting to JPEG. Choose PNG or WEBP if you need transparency.
- WEBP compatibility：Older browsers and systems may fail to open WEBP. Prefer PNG or JPEG for an audience you cannot predict.
- BMP files are huge：BMP is uncompressed and can be ten times larger than PNG. Only use it when print or a legacy system demands it.
- ICO is capped at 256px：Larger images are scaled down proportionally to fit the icon format ceiling.
- Very large images use memory：Processing several multi-thousand-pixel images at once may stall; cap the size first.
- Graceful fallback：If a browser cannot export WEBP the tool switches to PNG and tells you, rather than failing silently.
Output formats and quality
- Formats: PNG keeps transparency and is lossless, JPEG is smallest for photos, WebP offers a good balance, and AVIF gives the best compression where the browser supports encoding it.
- Quality slider: values near 90 are visually identical for most photos; below 70 banding may appear in skies and gradients.
Privacy and compatibility
- Nothing is uploaded: every pixel is decoded and re-encoded inside your browser, so private photos never travel over the network.
- Packaging: results are bundled into a single ZIP archive with sequential filenames, which keeps the original order intact.