Optimise JPEG images with precision controls — quality slider, progressive encoding and chroma subsampling. Achieve maximum compression with minimum visible quality loss. 100% browser-based.
Drag and drop a JPEG or JPG file onto the tool. The original file size and dimensions are displayed immediately. The tool accepts JPEG files up to 20 MB and processes them entirely in your browser without any server upload.
Use the quality slider (1–100) to control compression. Toggle Progressive JPEG to create files that load from blurry-to-sharp in browsers — better perceived performance for large images on slow connections. Adjust chroma subsampling for additional size savings on photographic content.
The before/after size comparison updates in real time. Use the comparison slider to visually inspect quality differences between the original and compressed versions at your chosen settings. When satisfied, click Download Optimised JPEG to save the file.
JPEG quality is a scale from 1 to 100 that controls how aggressively the lossy compression algorithm discards image data. At quality 100, minimal data is discarded and the file is large but nearly identical to the original. At quality 1, maximum data is discarded and the file is tiny but heavily artefacted. Most professional applications use quality 75–85 for web delivery and 90–95 for print.
A progressive JPEG loads in multiple passes — it first displays a low-resolution, blurry version of the full image, then progressively renders higher-quality detail with each subsequent pass. This gives the impression of faster loading because users see the whole image immediately (just blurry) rather than seeing it render top-to-bottom. Progressive JPEGs are typically 5–10% smaller than baseline JPEGs at the same quality.
Chroma subsampling exploits the human visual system's lower sensitivity to colour detail than brightness detail. It reduces the resolution of the colour (chroma) channels while keeping the luminance (brightness) channel at full resolution. The most common setting (4:2:0) reduces colour data to 25% of full resolution, achieving significant size savings with minimal perceptible quality loss in photographs.
For most website images, quality 75–80 provides the best balance of file size and visual quality — typically 60–75% smaller than the original while appearing virtually identical to casual viewers. Product images and hero banners where detail matters can use 80–85. Thumbnails and background images can safely use 65–70.
WebP achieves 25–35% smaller file sizes than JPEG at equivalent visual quality and is now supported by all modern browsers. If your audience is on modern browsers (Chrome, Firefox, Edge, Safari 14+), WebP is the better choice for web delivery. JPEG remains the universal fallback and is best for compatibility with older systems, email clients and software that doesn't support WebP.
Yes — each time a JPEG is re-saved with lossy compression, some additional data is discarded and artefacts accumulate. However, if you are reducing quality significantly (e.g., from quality 95 to quality 80), the result will be much smaller even if the source was already compressed. For minimal generation loss, always start from the highest-quality version available.
At low quality settings, JPEG introduces visible artefacts including: blocking (visible 8×8 pixel grid patterns), ringing (halos around sharp edges), colour bleed (colours bleeding across edges), and mosquito noise (buzzing around text and fine details). The comparison slider in this tool makes these artefacts easy to identify before downloading.
Highly complex images with fine textures (fabric, grass, foliage, crowds) and images with significant noise (grainy low-light photos) compress less efficiently than smooth, clean images. Additionally, if the source JPEG was already compressed at a moderate quality setting, there is less redundant data to remove. Starting from a raw or high-quality source always gives the best compression results.
Baseline JPEG loads from top to bottom — the image renders progressively from the first row of pixels to the last. Progressive JPEG loads in multiple passes over the entire image, starting blurry and sharpening with each pass. Progressive is generally preferred for web delivery due to better perceived performance. Both achieve similar final quality and file sizes, with progressive often being slightly smaller.
The JPEG Optimizer is specifically designed for JPEG files and its controls (chroma subsampling, baseline vs progressive) are JPEG-specific. For PNG compression, use our general Image Compressor tool. For maximum PNG compression, converting the image to JPEG first will typically yield much smaller files if the image is a photograph rather than a graphic with transparency or flat colours.
