About HEIC To Size

HEIC To Size started from one repeated annoyance: an iPhone photo that an upload form would not accept. The form wanted a JPEG under 100KB; the phone produced a 2–3 MB HEIC. The usual fix is to convert the photo somewhere, open it in an editor, lower the quality, export, check the size and repeat — or to upload a passport scan to a stranger's server. This site does the whole job in one step, on your own device.

Who is behind it

HEIC To Size is built and maintained by an independent developer, not a company. The first version was written in July 2026. The complete source code is public on GitHub under the AGPL-3.0 licence, so every claim on this site — including "your photo is not uploaded" — can be checked against the code that actually runs.

How it works

The compression engine is written in Rust and compiled to WebAssembly. It decodes HEIC with a pure-Rust HEVC decoder, then searches JPEG quality between 100 and a floor of 55 for the highest quality that fits your target. If the photo is still too large at the floor, it scales the image down with a Lanczos3 filter instead of dropping quality further. Colour profiles are preserved; EXIF metadata such as GPS location is not copied into the result. PNG output is lossless, so it reaches the target by adjusting dimensions only. The homepage explains each step and shows measured results.

Deliberate limits: one photo at a time, targets from 5KB to 5000KB, JPEG or PNG output. Lossy WebP is not offered because the only mature encoder is a C library, and the project keeps the engine pure Rust so that it builds reproducibly for the browser.

How it is tested

• Rust unit tests compress real HEIC files — iPhone photos, Android samples and reference files from the libheif project — to fixed targets and fail if any output is even one byte over its target or below the quality floor.
• Browser tests (Playwright, Chromium and WebKit) load the real site, compress a real HEIC, download the result and check its format and size, on desktop and mobile layouts.
• Both suites run in continuous integration on every change, and the browser suite is also run against the live production site.
• The measured results table on Reduce HEIC file size is generated by a test in the repository, so the numbers can be reproduced rather than taken on trust.

How the guides are written

Each guide on this site describes what the tool itself does at that size: which settings it chooses, what the trade-offs are and when a different target or format would serve you better. Guides are updated when the engine changes. If you find a statement that does not match what the tool does, please report it — it will be corrected.

How the site is funded

The tool is free and has no account or paid plan. The site may show a small number of clearly labelled advertisements on its article pages; ads are never placed inside the compression tool, and advertising code cannot access your photo. See the privacy policy for details.

Contact

Questions, bug reports and corrections: [email protected]. You can also open an issue on GitHub. Please do not email photos unless we ask for a sample to reproduce a bug.

heictosize · last reviewed September 2026