Compress JPEG to an exact file size — without visible loss

Every other JPEG compressor hands you a quality slider and wishes you luck. Scalir asks a more useful question — how big is the file allowed to be? — and then binary-searches the encoder for the highest quality that fits: 1 MB, 500KB, whatever you set. The search runs on your own machine across all CPU cores, so a few hundred photos land under budget in the time a cloud tool spends uploading the first one.

Preconfigured for JPEG output — set your own size target below.

Drop images here

or

Choose files

JPG, PNG, WebP, AVIF, HEIC, GIF, TIFF, BMP · processed on your device, never uploaded

Max size (MB)

Target file size — we compress just enough to fit under this. Output format Auto keeps the original, switching to WebP only when it helps. Or force one format (AVIF is the smallest, but slower to encode).

JPEG quality numbers, decoded

What the 1–100 scale actually looks like in practice.

Quality	What you get
95	Archival — indistinguishable from the source, biggest files
85	The sweet spot — visually clean at a fraction of the size
75	Standard web quality — fine for photos in a page layout
60	Scalir's default floor — compact, still respectable
Below 60	Blocking and smearing start to show; used only if you allow it

Two levers, and which one to pull

File size responds to two things: pixel dimensions and encoder quality — and dimensions are by far the stronger lever. Halving the width quarters the pixel count before quality even enters the picture, which is why Scalir pairs your size target with a 2000px longest-side cap by default.

The quality search then does the fine-tuning: encode, measure, adjust, landing the best quality that fits your budget. If a file cannot fit above your quality floor, it is flagged instead of ruined — you decide whether to lower the cap and rerun.

Compress JPEGs to a target size

Queue up the photosDrag in files or a folder; hundreds at a time is normal use.
Name your budgetKeep the 1 MB default or type an exact figure. The quality floor guards against over-compression.
Verify and downloadOpen any result in the before/after compare view, then grab the batch as a ZIP or save to a folder.

Frequently asked questions

How do I compress a JPEG without losing quality?

Visually lossless compression means staying above the quality where artefacts appear. Scalir searches for the highest quality that fits your size target and never goes below your quality floor, so results stay clean — and the before/after preview lets you verify any file.

How does Scalir hit an exact JPEG file size?

It runs a binary search over encoder quality: encode, measure, adjust — landing the best quality that still fits under your target, rather than guessing with a fixed slider.

Can I compress many JPEGs at once?

Yes — that is the point. Drop in hundreds of photos or a whole folder and they are compressed in parallel across your CPU cores, then downloaded as a ZIP or saved to a folder.

Is it safe to compress JPEGs online?

With Scalir, yes — "online" only means it runs in your browser. Photos are compressed on your own device and never uploaded, and EXIF metadata including GPS location is stripped from the output.