PNG or JPG from your HEICs?
PNG when the photo faces editing, compositing, or print prep — the encode is lossless, so you lose nothing before your work begins. Files are large (photos don't compress well losslessly). JPG when the photo is headed for sharing, forms, or storage — visually identical, 5-10× smaller. Both run entirely in your browser with the current-generation HEIC decoder (many converter sites still run a 2021 decoder that chokes on iOS 18 photos).
FAQ
Why are the PNGs so big?
Lossless photo encoding is inherently large — a 24MP photo can be 30-60 MB as PNG. That's the price of "zero loss"; if size matters, JPG at high quality is visually indistinguishable.
HDR HEIC photos?
You get the standard-look SDR image every app displays correctly. Washed-out photo problems live at the un-HDR fixer.