Image Compressor
Reduce image file sizes in your browser.
Drop your images here
Supports JPG, PNG, WebP, AVIF, and BMP. Animated GIF is not supported. Up to 30 images (max 30 MB each).
Compression settings
Reduce Image File Sizes with Adjustable Compression
Large digital photos and unoptimized graphic assets can contribute to slower website loads, larger email attachments, and higher data use. This compressor works in your browser, so selected images are not uploaded to a conversion server.
The tool accepts JPG, PNG, WebP, AVIF, and BMP files when the browser can decode them; animated GIF is not supported. The default output keeps JPEG, PNG, or WebP, while AVIF and BMP default to JPEG. You can also choose JPEG, PNG, or WebP output, adjust the browser encoder quality value, compare the preview, and download each result. Selected files may be saved in this browser for up to 7 days to support refresh recovery; Reset clears saved tool data.
Lossy vs. Lossless Compression: How It Works
Compression changes how pixels are encoded, but does not guarantee that the new file will be smaller or look the same. The browser decodes the source, may resize it if you choose a resolution cap, then encodes a new file:
Lossy output (JPEG & WebP)
JPEG and WebP can use lossy encoding. The selected quality value is passed to the browser encoder; appearance and file size depend on the source, dimensions, and browser implementation. Inspect the output.
Lossless Compression (PNG)
PNG encoding is lossless for the pixels passed to the encoder. If you selected a resolution cap, those pixels may already have been resampled. PNG output can be larger than the source, and the quality slider does not affect PNG encoding.
Compression Presets and Browser Quality Values
These preset numbers are browser encoder quality values. They do not describe a percentage of original detail retained or predict a byte-size reduction. Compare the actual preview and size before choosing a result:
| Preset | Encoder quality value | What to check |
|---|---|---|
| High Quality | 88% | Inspect image details and output size before use |
| Balanced | 75% | Compare preview at the size where it will be shown |
| Maximum Compression | 50% | Check for visible artifacts and confirm the output is smaller |
Why Output Size Varies by Image
Re-encoding the same image can make its file larger or smaller. PNG, JPEG, and WebP use different encoding methods, and the result also depends on dimensions, detail, transparency, and the browser's encoder.
Use the per-image size change and side-by-side preview to decide whether the new file meets your needs. PNG and WebP can retain transparency. JPEG cannot; this tool composites transparent areas onto white for JPEG output.
Browser Safety & Device Memory Guardrails
Image decoding, optional resizing, preview generation, and encoding run in your browser. The selected files are not sent to a conversion server; local processing still uses device memory and browser resources.
These limits bound the queue and each input file, but cannot guarantee that every device has enough memory for every image.
- Batch ceiling: Batches are capped at 30 files, with a 30 MB maximum per file. This does not guarantee that every device has enough memory for every accepted image.
- Resolution limit: Maximum image dimensions are checked at50 Megapixels. A 50 MP RGBA bitmap alone is about 200 MB before browser overhead.
- Bounded queue: At most two image jobs run at once; device memory use still varies with image dimensions, the browser, and other open tabs.
Local image processing
Frequently Asked Questions About Image Compression
What is the difference between lossy and lossless image compression?
Lossy formats such as JPEG and WebP trade some image data for potentially smaller files. PNG encoding is lossless for the pixels supplied to the encoder. Actual file-size changes depend on the input format, image content, dimensions, browser encoder, and settings.
Does compressing images locally cause noticeable blurriness or color degradation?
The preset numbers are values passed to the browser's image encoder. They are not percentages of detail retained or promises of file-size reduction. Compare the preview and output size for your own image, especially around fine text, edges, gradients, and skin tones.
Can converting to WebP change file size compared with JPEG or PNG?
WebP can produce a smaller or larger file depending on the image, browser encoder, dimensions, and quality setting. It can preserve transparency. Compare the actual output size and preview before using it.
What happens to selected files and saved tool data?
Image compression runs in your browser and selected images are not uploaded to a conversion server. To restore work after refresh, selected files may be saved in this browser for up to 7 days; Reset clears saved tool data. Normal page and asset requests still reach our host. If you allow analytics, FivoTools records limited tool-usage events, not image contents or filenames.
When should I choose "Balanced" versus "Maximum Compression"?
Balanced (75%) and Maximum Compression (50%) set different browser encoder quality values. Compare the preview and output size for your own image before choosing a setting; neither preset guarantees a specific file-size saving.
Related Image Optimization Tools
Explore our comprehensive suite of local browser media utilities in the Image Tools Hub:
- Bulk Image Resizer - Adjust pixel dimensions and aspect ratios across batches of images.
- HEIC → JPG Converter - Convert Apple iPhone photos to widely supported JPG files in batch.
- AVIF → JPG / PNG Converter - Convert next-gen AVIF images into standard web formats.
- JPG / PNG → PDF Converter - Compile multiple compressed photos into a clean PDF document.
Technical References
- ITU-T Recommendation T.81 (ISO/IEC 10918-1): The official specification for JPEG lossy continuous-tone still image compression.
- Google for Developers WebP Container Specification: Documents WebP lossy and lossless coding, transparency, and file structure.Read the specification.
- W3C PNG Specification, Third Edition (2025): Defines the PNG format, including lossless raster image storage and optional alpha transparency.Read the specification.
- MDN canvas export reference: Describes canvas image export, browser-supported output formats, and the quality argument for lossy encoders.Read the reference.