Compress JPEG
Process images in your browser — your files never leave your device.
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What is the Compress JPEG?
This tool compresses JPEG photos by re-encoding them with a smaller discrete cosine transform (DCT) quantization step — the same lossy technique every JPEG encoder uses, just with a quality number you control. Drop in one or more .jpg files, move the quality slider, and download files that are typically 60–85% smaller with no visible change at normal viewing size. It runs entirely in your browser through the Canvas API and the browser-image-compression library, so a 5,000-photo folder never has to leave your machine. It is built for people who need JPEGs specifically — photographers exporting for web, sellers uploading product shots, anyone attaching photos to email.
You can also set a max dimension or a target file size in MB instead of, or alongside, the quality slider. Setting a max dimension shrinks the pixel grid before compression runs, which cuts file size far more aggressively than quality alone — useful when a photo is both oversized and needs to hit a hard limit like a 2 MB upload cap.
Why use a free compress jpeg?
Built for one format, not three
Output is locked to JPEG, so there is no format dropdown to get wrong. Every control on the page — quality, max dimension, target size — does one job on one format.
60–85% smaller at quality 70–80
A typical photo compresses to a fifth or less of its original size in that range with no visible artefacts at normal screen size. The exact number depends on how much fine detail the photo has.
Batch processing with one ZIP download
Drop in as many JPEGs as you want, compress them all with the same settings, and download everything as a single ZIP instead of saving files one at a time.
Target size mode
Enter a size in MB and the tool works backward from it, resizing and re-encoding until the output fits — useful for platforms with a hard upload limit rather than a quality target.
Nothing leaves your browser
Compression runs on-device via the Canvas API and a WebWorker. Your original files are never sent to a server, which matters for unpublished photos or client work under NDA.
How do you use the Compress JPEG?
- 1
Add your JPEG files
Drag and drop one or more .jpg/.jpeg files, or click to browse. Each file gets its own row with a live thumbnail.
- 2
Set quality, max dimension or target size
Quality (10–100%) controls how aggressively the DCT quantization discards data. Max dimension caps the longest side in pixels. Target size in MB tells the tool to hit a specific file size — all three are optional and can be combined.
- 3
Compress
Click Compress. Each file processes locally; a progress bar tracks each one individually for large batches.
- 4
Check the before/after size
Each row shows original size, compressed size and the percentage saved. Zoom in on a couple of files to confirm quality is still acceptable before downloading the rest.
- 5
Download one file or the whole ZIP
Download files individually, or use "Download all as ZIP" once more than one file is done.
How is compress jpeg calculated?
Reduction % = (original size − compressed size) ÷ original size × 100Where:
- original size
- Size of the source JPEG in bytes
- compressed size
- Size of the re-encoded JPEG at the chosen quality
- quality (10–100)
- Passed to the encoder as initialQuality — controls the DCT quantization step size used when re-encoding each 8×8 pixel block
The simple version
JPEG splits an image into 8×8 pixel blocks, transforms each block into frequency data, then throws away the frequencies the human eye notices least — fine detail and colour variation, mostly. The quality number controls how much gets thrown away. High quality keeps almost everything and the file stays large; low quality throws away more and the file shrinks, but you start to see square-shaped blocking where detail used to be.
What does it look like in practice?
Phone photo at a sensible default
Input
4.2 MB JPEG, 4032×3024, quality 80
Result
~520 KB, same dimensions, no visible change
This is the typical outcome for a well-exposed photo with natural texture like skin, fabric or foliage — detail that hides DCT blocking well.
Hitting an email attachment limit
Input
18 MB of nine JPEGs, target size set to 1.5 MB each
Result
Nine files, each ≤1.5 MB, ZIP downloaded as one file
Target size mode adjusts quality (and dimension, if needed) per file until each one lands under the cap — faster than tuning quality by hand nine times.
Aggressive compression for a thumbnail
Input
Same 4.2 MB JPEG, quality 30, max dimension 800px
Result
~45 KB, resized to 800×600
Combining a lower quality with a smaller max dimension compounds the savings — most of the reduction here comes from the dimension cap, not the quality drop alone.
How accurate is it?
Compression runs through the same Canvas-based JPEG encoder your browser uses everywhere else, wrapped by browser-image-compression for the quality/size-targeting logic. The size shown after compression is the exact size of the file you download.
- Compression ratio depends on image content, not just the quality number — a busy, high-detail photo compresses less at the same setting than a smooth, low-detail one.
- Below roughly quality 40–50, blocking artefacts become visible in flat areas (skies, shadows, gradients) even at normal viewing size.
- Target size mode is not exact to the byte — it converges close to your target but may land a little above or below it depending on the image.
- JPEG has no alpha channel. If a source file somehow carries transparency data, it is discarded — JPEGs are always fully opaque.
What should you know before using it?
How JPEG compression compares to PNG and WebP:
| Format | Compression mechanism |
|---|---|
| JPEG | Lossy DCT with adjustable quantization. No transparency. Best for photos and continuous-tone images. |
| PNG | Lossless DEFLATE. No quality slider that does much — see Compress PNG for why. |
| WebP | Hybrid — lossy VP8-based compression at adjustable quality, or a lossless mode. Usually beats JPEG at equal visual quality. |
Which tools relate to the compress jpeg?
The compress jpeg is one of 31 image tools on this site. These are the ones most often used alongside it — either because they handle the next step in the same job, or because they answer a question this tool raises.
Compress PNG
The lossless counterpart — for screenshots, logos and anything with transparency, where JPEG is the wrong format regardless of size savings.
Compress WebP
Convert to WebP first if your target platform accepts it — a WebP at equivalent visual quality is usually smaller than a compressed JPEG.
Image Resizer
Reducing pixel dimensions before compressing shrinks a file far more than quality adjustment alone, especially for images displayed smaller than their source resolution.
Image Compressor
The all-format version of this tool — use it when your batch mixes JPEG, PNG and WebP files and you want one workflow for all of them.
When should you use a compress jpeg?
Because the compress jpeg runs entirely in your browser, it suits work you would not want to hand to a third-party server — client files, unpublished drafts, anything under an NDA. These are the situations people reach for it in most often.
Product photography for online stores
Marketplaces and storefronts often cap upload size or recompress oversized images themselves, losing more quality in the process. Compressing to a sensible size before upload keeps you in control of the result.
Web performance
Uncompressed camera JPEGs are the most common cause of slow page loads. Compressing hero images and photo galleries directly improves load time and Core Web Vitals.
Email and messaging attachments
Most providers cap attachment size around 20–25 MB. Batch-compressing a folder of event or product photos gets a whole shoot under that limit in one pass.
HEIC photo workflows
iPhones save photos as HEIC by default. Convert to JPEG first with the HEIC to JPG converter, then compress here for a smaller, universally compatible file.
Open the HEIC photo workflowsFrequently asked questions
What quality setting should I use to compress a JPEG?
How much can I compress a JPEG without losing visible quality?
Does compressing a JPEG multiple times make it worse?
Can I compress a JPEG to a specific file size?
Is compressing JPEGs here safe for private photos?
Why does my compressed JPEG still look blurry, not blocky?
What's the difference between this and the general Image Compressor?
Is the compress jpeg safe to use?
This tool runs entirely inside your browser. Your text, files and settings are processed on your own device and are never uploaded to our servers — there is nothing for us to store, log or leak. You can confirm it yourself: open your browser DevTools, switch to the Network tab, and use the tool. You will not see an upload request. It also means the tool keeps working if your connection drops mid-task.
Where do these figures come from?
Every method, threshold and standard this page relies on, with a link to the document that defines it. Check them — a tool that will not show its sources is asking you to take its word for it.
- 1Information technology — Digital compression and coding of continuous-tone still images: Requirements and guidelines
ITU-T Recommendation T.81 / ISO/IEC 10918-1 · 1992
Supports: The DCT-based, 8×8 block quantization compression method described as the basis of JPEG encoding.
- 2Image file type and format guide
MDN Web Docs
Supports: The comparison of JPEG against PNG and WebP as a lossy format with no alpha-channel support.
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