JPG to HEIC

Size, mostly. HEIC stores the same picture in roughly half the bytes of a JPG at comparable quality, which is why iPhones shoot it by default — a photo library moved to HEIC takes about half the space. It is also the format Apple devices handle most naturally, and it keeps transparency, which JPG cannot.

No, and no converter can. Whatever the JPG already lost is gone; re-encoding it as HEIC makes the file smaller, not sharper. Convert when you want the space back or need a HEIC file — not as a repair.

Yes. The file is a standard HEIF still image with HEVC-coded pixels — the same container Apple’s Camera writes — so Photos, Finder and Quick Look open it directly. On Windows 10/11 you may need the HEIF Image Extensions from the Microsoft Store; most Android phones open HEIC natively since Android 10.

No — and that is unusual for this conversion. HEIC encoding almost always runs on someone else’s server, because it needs a video-grade encoder. Here it runs inside your browser as WebAssembly: your photo is never uploaded, and the conversion still works with the network off.

A second or two for a typical photo, a few seconds for a 12–24 megapixel one — HEIC compression is genuinely heavier work than JPG. It runs in a background thread, so the editor stays usable while it encodes.

Yes. The download dialog has the same 0–100 quality slider for HEIC as for JPG, and the format menu shows what the file will weigh before you save it. Most online HEIC converters give you whatever their encoder defaults to; this one runs its own encoder in your browser, so the setting is yours. There is also an exact byte budget — "under 100 KB" — for HEIC as well as for JPG and WEBP: the "target file size" mode encodes the picture several times to find the quality that fits, and shows its progress because with HEIC that search takes a few seconds.

No. PIXLFLW runs entirely in your browser: images are opened, edited and exported locally on your device and are never uploaded, stored or seen by anyone.

Yes, completely free — no sign-up, no watermarks and no daily limits. The only practical limit is your browser memory for very large files (up to 20 MB per image).