How to use the image compressor

Drag your photos onto the drop zone, or click Choose files. You can add JPEG, PNG, WebP, HEIC, GIF and BMP files, and as many of them as you like.
Set the quality slider. 80 is a good default; drop to 60–70 when file size matters more than fine detail.
Optionally pick an output format. “Keep original” leaves JPEGs as JPEGs, while WebP usually produces the smallest file of the three.
Tick Also resize larger images and enter a maximum width or height if the originals are bigger than they need to be.
Press Compress, then download files one at a time or use Download all.

Each row shows the original size, the new size, and the percentage saved, so you can tell at a glance whether the settings were worth it.

How image compression actually works

JPEG and WebP are lossy formats. Instead of storing every pixel, the encoder converts small blocks of the image into frequency components and rounds away the ones your eye is least likely to notice — fine texture, subtle gradients in shadow, and colour detail, which human vision resolves far more coarsely than brightness. The quality setting controls how aggressively that rounding happens.

Setting	Typical result on a photo	Good for
90–100	Almost no saving, very large files	Archiving, print masters
80–90	50–70% smaller, visually identical	Most web images
60–80	70–85% smaller, slight softening	Blog posts, product grids
Under 50	Blocking and colour banding visible	Thumbnails only

PNG works differently. It is lossless: it compresses by finding repeated patterns, so it never discards detail and never blurs edges. That makes it excellent for screenshots, logos and line art, and poor for photographs. Because the browser canvas can only write lossless PNG, the quality slider has no effect on PNG output — converting to WebP is the way to make a large PNG smaller.

Resizing is the other big lever, and usually the one people forget. A 4032 × 3024 phone photo has 12.2 million pixels. Scaled to 1920 × 1440 it has 2.8 million — roughly a quarter as much data before compression even starts. If an image will be displayed 800 pixels wide, storing it at 4000 pixels wide is pure waste.

Worked examples

A phone photo for a blog post. A 4.2 MB JPEG at 4032 × 3024, compressed at quality 80 with a 1920 px width limit, typically lands around 320–420 KB. That is roughly a 90% reduction, and at normal viewing size the two are indistinguishable.

A screenshot saved as PNG. A 1.8 MB PNG screenshot re-encoded as PNG stays about 1.8 MB, because nothing lossy happened. The same screenshot exported as WebP at quality 85 usually lands near 180–260 KB — around 85% smaller — while text stays crisp.

An already-optimised image. A 90 KB JPEG that a CMS already processed may come out at 95 KB. When that happens the tool keeps your original file and says so, because re-compressing would only add artefacts for no benefit.

Tips and common mistakes

Always compress from the original. Each lossy save bakes in the previous round’s artefacts. Compressing a compressed file twice at quality 80 looks worse than compressing the original once at quality 65.
Resize before you agonise over quality. Halving the dimensions saves more than dropping quality from 85 to 60, and it costs far less visible detail.
Match the format to the content. Photographs belong in JPEG or WebP. Screenshots, diagrams, logos and anything with sharp edges or flat colour belong in PNG or WebP.
Watch transparency. JPEG has no alpha channel, so transparent areas are filled with white when you convert a PNG to JPEG. Choose WebP if you need the transparency preserved.
Check the biggest offenders first. In most page-weight audits, two or three oversized hero images account for the bulk of the problem.
Very large files need patience. Anything over about 50 MB is decoded entirely in memory in this tab, which can be slow on a phone.

Privacy

Your images are never uploaded. The tool reads each file with the browser’s File API, decodes it into an offscreen canvas, and re-encodes it locally. There is no server component, no queue and no temporary storage: when you close or reload the page, every file and preview is discarded, and the preview URLs the tool created are revoked. That also means the tool works offline once the page has loaded.

Frequently asked questions

How much smaller will my images get?

A typical smartphone JPEG shrinks by 60–80% at quality 80 with no visible difference on screen. Photos that are already compressed, screenshots with flat colours, and small thumbnails save far less.

Does compressing an image reduce its resolution?

Not by itself. Quality only changes how much detail the encoder throws away. Pixel dimensions stay the same unless you turn on the resize option and set a maximum width or height.

Why doesn't the quality slider change my PNG file size?

PNG is a lossless format, and the browser canvas only writes lossless PNG. The slider is ignored for PNG output. Choose WebP instead, which supports lossy compression and usually cuts a PNG by half or more.

Can I compress HEIC photos from my iPhone?

Yes. HEIC and HEIF files are decoded in the browser first, then re-encoded as JPEG or WebP. The converted file keeps the same pixel dimensions.

Is image quality lost every time I compress?

Yes, for lossy formats. JPEG and WebP discard information permanently, and re-compressing an already compressed file degrades it further. Always start from the original rather than a compressed copy.

Are my photos uploaded anywhere?

No. The files are read with the browser's File API and re-encoded with canvas on your own device. No copy is sent to a server, and closing the tab discards everything.

Related tools

Last reviewed: September 21, 2026

Image Compressor

⚙️ Options