Image formats are a compatibility problem wearing a technology costume. HEIC is genuinely better compression than JPG — and the first thing most people need to do with a HEIC file is turn it into a JPG so something will open it. Knowing what each format is actually for turns the "which one?" question from guesswork into a thirty-second decision.
HEIC: better, and that's the problem
In 2017 Apple switched the iPhone camera to HEIC, which stores photos at roughly half the size of an equivalent JPG. On the phone, this is invisible and free. The trouble starts when a photo leaves: Windows needs a paid codec it does not ship, no web browser will display a HEIC, and plenty of upload forms reject it outright. HEIC is an excellent camera format and a poor exchange format.
The fix is a conversion at the moment of sharing. Our converter decodes HEIC in your browser — most tools that handle HEIC upload your photo to a server to do this, which for personal photos with embedded GPS positions is worth caring about.
JPG: the universal donor
JPG's compression is built around a fact about human eyes: we notice brightness far more than colour detail, and we barely notice small errors in smooth gradients. For photographs it produces small files whose flaws are hard to see. Point the same trick at hard edges — text, logos, screenshots — and it produces the familiar smudgy halo, because a sharp edge is exactly the thing its mathematics cannot represent cheaply.
Its other limitation is invisible until it bites: no transparency. Every pixel of a JPG must be a colour, so converting a transparent PNG means choosing a background — our tool fills white, matching what documents and most sites expect.
PNG: exact, at a price
PNG is lossless: what goes in comes out, pixel for pixel, however many times it is opened and re-saved. That makes it the right container for anything where edges are the content — screenshots, diagrams, logos, text — and for anything needing transparency. It also makes it the wrong container for photographs, where reproducing sensor noise exactly can cost five to ten times the file size of a JPG nobody could tell apart from it.
One caution: converting a JPG to PNG does not restore quality. The detail JPG discarded is gone; PNG just preserves the loss exactly.
WebP: the web's compromise
WebP does both jobs — lossy compression like JPG (typically 25–30% smaller at matching quality) and transparency like PNG — and every current browser supports it, which is why sites serve it and why files saved from the web keep arriving in it. Outside the browser its support is patchier: older photo editors, corporate systems and printers still reject it, which is how "webp to jpg" became one of the most-typed conversion searches on the internet.
What conversion actually does
Every conversion here decodes the image to raw pixels and re-encodes it in the target format. Two consequences are worth knowing. First, re-encoding into a lossy format discards a little information each time — one conversion at high quality is harmless for photos, but repeated save-edit-save cycles accumulate damage, so keep an original and convert from that. Second, the redraw carries only pixels: EXIF metadata — GPS coordinates, camera model, timestamps — does not survive it. For a photo headed to the public internet, that is usually exactly what you want.
FAQ
Why won't my iPhone photos open on Windows?
Since 2017, iPhones save photos as HEIC by default — a format that compresses roughly twice as well as JPG at the same quality. Windows does not ship the codec for it, and no web browser can display it, so the file arrives as an unopenable attachment. Converting it to JPG makes it universal; the conversion happens in your browser and the photo is never uploaded anywhere.
Does converting an image lose quality?
Converting into a lossy format — JPG or WebP — re-encodes the pixels and discards a little information each time, so repeated cycles of editing and re-saving gradually accumulate damage. One conversion at high quality is visually indistinguishable for photos. Converting into PNG never discards anything, but it also cannot recover detail the source format already threw away, and for photos the file gets dramatically larger.
When should I use PNG instead of JPG?
PNG for anything with hard edges or transparency: screenshots, logos, diagrams, text. JPG's compression is designed for the smooth gradients of photographs and produces visible ringing artefacts around sharp edges, while PNG reproduces them exactly. For an actual photograph the trade reverses — PNG files of photos are enormous for no visible benefit, and JPG at high quality is the right choice.
Why does a transparent PNG get a white background when converted to JPG?
JPG has no alpha channel — every pixel must be a colour, so the transparent areas have to become something. Our converter fills them with white, which is what most documents and websites expect. If you need the transparency preserved, convert to WebP or keep PNG; those formats carry an alpha channel and JPG simply cannot.
Related guides
- How to compress images without losing quality — once the format is right, this is how you make the file smaller.
- How to convert JPG to PDF — the next step when the photos are becoming a document.
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