Why is the resulting PNG often larger than the source WebP?

WebP (RFC 9649 Zern, Massimino & Alakuijala, Google LLC, November 2024) typically delivers 25–35% smaller files than equivalent lossless PNG (W3C Recommendation 10 November 2003 / ISO/IEC 15948:2004) thanks to VP8's prediction modes (lossy) or LZ77 + Huffman/prefix coding plus colour cache and four reversible transforms (lossless mode per RFC 9649 §3). PNG uses lossless DEFLATE (RFC 1951 Deutsch, May 1996, LZ77 + Huffman with 32 KB sliding window) which preserves every pixel exactly but compresses less aggressively for natural images. Converting WebP → PNG produces a PNG that's typically 30–50% larger than the source for photographs; the trade buys universal compatibility (every editor, OS, and CMS reads PNG) at the cost of file size.

Does the alpha channel transfer cleanly between WebP and PNG?

Yes, for both directions of the WebP↔PNG round-trip. PNG supports both palette transparency (1-bit, via tRNS chunk) and full 8-bit alpha (RGBA mode) per W3C 2nd Edition. WebP supports an 8-bit alpha channel both in lossless mode and as an extension in lossy mode (ALPH chunk per RFC 9649 §2.7.1.2). The Canvas 2D Context conversion path preserves alpha values exactly: decode WebP → ImageBitmap with alpha → drawImage → toBlob('image/png') retains every alpha byte. Unlike WebP→JPG conversions where alpha must be flattened against a background, WebP→PNG keeps every transparent pixel transparent.

Why convert WebP to PNG at all if the result is bigger?

Compatibility, not size. PNG is universally accepted: every desktop editor (Photoshop, GIMP, Affinity), every OS preview tool, every CMS, every print pipeline, every Office document accepts PNG. WebP support is broad in browsers (Chrome 32+ since 2014, Firefox 65+ since January 2019, Safari 14+ since 16 September 2020) but still patchy in legacy desktop tools and certain workflows (older Photoshop versions, some print services, specific archival systems). The conversion is the right choice when the destination cannot handle WebP, accepting the size penalty as the cost of portability.

WebP to PNG Converter Online — Modern WebP to Universal PNG

Q: If the source WebP was lossy, will the PNG quality match the original photograph?

No. WebP's lossy mode (VP8 keyframes per RFC 6386 Bankoski et al., November 2011) discards high-frequency DCT coefficients and applies in-loop filtering during encoding — those losses are baked into the decoded pixels. PNG is lossless from the decoded WebP onward, but cannot recover detail the original WebP encoder discarded. Lossless WebP sources (per RFC 9649 §3) produce PNGs that match the WebP exactly pixel-for-pixel. The PNG is a 'compatibility wrapper' for whatever pixels the WebP decode produced — not a fidelity restoration.

Q: Does Safari work the same as Chrome for this conversion?

Yes. WebP decoding (the input direction) is universally supported including Safari since version 14 (16 September 2020 / iOS 14). PNG output via Canvas toBlob('image/png') is also universally supported across all modern browsers including Safari. The Safari WebP limitation only applies to the inverse direction (toBlob('image/webp') for PNG → WebP encoding) which is not supported natively in Safari as of 2026 — a WebKit limitation tracked at bugs.webkit.org. WebP → PNG runs cleanly everywhere.

WebP converts to PNG for universal compatibility.PNG (1996) opens in every image viewer, editor, and legacy system. Trade-off: file size grows ~30% vs lossless WebP and you lose WebP's animation support — keep the original WebP for re-export if you ever need it back.

WebP vs PNG comparison

Format-by-format properties. Convert to PNG when you need broadest editor and viewer compatibility — every tool supports PNG.
Property	WebP	PNG
Compression	Lossless (VP8L) or lossy (VP8)	Lossless (DEFLATE)
Lossless file size	~150-370 KB	200-500 KB (~30% larger)
Alpha channel	Yes (RGBA)	Yes (RGBA)
Animation	Yes (native, since 2010)	No (use APNG)
Color depth	8 bits/channel	8 or 16 bits/channel
Year introduced	2010 (Google, RFC 6386)	1996 (RFC 2083)
Browser support	97% (Safari 14+, FF 65+)	Universal (~100%)
Best for	Modern web, smaller bandwidth	Universal compatibility
EXIF metadata	Supported (libwebp 0.5+)	Via tEXt / iTXt chunks
Max dimensions	16383 × 16383 px	2³¹−1 px each side
Patents	Royalty-free (Google grant)	Patent-free since 1996
Image-editor support	Modern (Photoshop 23+, GIMP 2.10+)	Universal (every editor)

WebP to PNG Converter — Lossless Compatibility for Alpha-Bearing Images

WebP (RFC 9649 Zern, Massimino & Alakuijala, Google LLC, November 2024) and PNG (W3C Recommendation 10 November 2003 / ISO/IEC 15948:2004) sit on opposite sides of the modern-vs-universal compression tradeoff. WebP delivers 25–35% smaller files thanks to VP8 prediction modes (lossy mode per RFC 6386 Bankoski et al., November 2011) or LZ77 + Huffman/prefix coding plus colour cache and four reversible transforms (lossless mode per RFC 9649 §3). PNG uses straightforward DEFLATE (RFC 1951 Deutsch, May 1996, LZ77 + Huffman over filtered scanlines) — less efficient but readable by every editor, OS, CMS, and print tool ever shipped. The conversion preserves alpha exactly: WebP's ALPH chunk (per RFC 9649 §2.7.1.2) decodes to canvas RGBA pixels, then PNG's tRNS chunk or RGBA mode preserves every transparent pixel. The trade is universal compatibility at the cost of file size — typically 30–50% larger than the source WebP for photographs.

How to convert WebP to PNG

Drop a .webp file onto the tool or click to browse — single file or batch.
The browser decodes the WebP bitstream (per RFC 9649) to an ImageBitmap and draws it to a Canvas at native dimensions, preserving alpha.
Canvas calls toBlob('image/png') which encodes the pixels via DEFLATE (RFC 1951) into a PNG (W3C 2nd Edition / ISO/IEC 15948:2004) — no quality slider needed since PNG is lossless.
Download the PNG. Alpha channel is preserved exactly. Original WebP file is not modified.

Common use cases

Opening a WebP download in a legacy desktop editor (older Photoshop versions, certain RAW workflows) that doesn't decode WebP natively.
Feeding a WebP into a CMS, design tool, or archival pipeline that strictly expects PNG input.
Archiving a WebP as PNG for long-term storage where decoder availability decades from now is uncertain.
Producing a lossless PNG master from a WebP source before re-exporting to a different format pipeline (TIFF, BMP, ICO).

Frequently asked questions

Why is the PNG often larger than the source WebP?

WebP (RFC 9649, Nov 2024) is 25–35% smaller than PNG at equivalent quality thanks to VP8 prediction (lossy) or LZ77 + Huffman + colour cache + reversible transforms (lossless §3). PNG uses lossless DEFLATE (RFC 1951 May 1996). Expect 30–50% growth for photos.

Does the alpha channel transfer cleanly?

Yes. PNG supports tRNS palette transparency + 8-bit RGBA (W3C 2nd Ed). WebP supports 8-bit alpha via ALPH chunk per RFC 9649 §2.7.1.2. Canvas conversion preserves alpha bytes exactly. Unlike WebP→JPG which flattens alpha, WebP→PNG keeps every transparent pixel transparent.

If the source WebP was lossy, will the PNG quality match the original?

No. WebP lossy (VP8 keyframes per RFC 6386 Bankoski et al., Nov 2011) discards detail at encode time — PNG cannot recover what was already discarded. PNG is lossless from the decoded WebP onward but inherits any baked-in WebP artefacts. Lossless WebP sources match pixel-for-pixel.

Why convert WebP to PNG if the result is bigger?

Compatibility, not size. Every desktop editor, OS preview, CMS, print pipeline, Office document accepts PNG. WebP support is broad in browsers (Chrome 32+ 2014, Firefox 65+ Jan 2019, Safari 14+ Sept 2020) but patchy in legacy desktop tools and archival systems.

Does Safari work the same as Chrome for this conversion?

Yes. WebP decoding is universally supported including Safari 14+ (16 Sept 2020 / iOS 14). PNG output via toBlob('image/png') is universally supported. Safari's WebP limitation only applies to the inverse direction (PNG → WebP encoding) which hits a WebKit limitation; WebP → PNG runs cleanly everywhere.

What WebP → PNG actually does — and why it's a compatibility move

The conversion is decode-the-WebP-to-pixels then re-encode-as-PNG via the WHATWG Canvas 2D Context + HTMLCanvasElement.toBlob('image/png') API. WebP decoding is universally supported across browsers including Safari since version 14 (16 September 2020 / iOS 14), so this conversion direction has no platform restrictions — the inverse PNG→WebP direction hits the well-known Safari limitation (no native toBlob('image/webp') output) but WebP→PNG runs cleanly everywhere. The pixel preservation is exact: every bit the WebP decoder emits is what PNG encodes. If the source WebP was lossy (VP8 keyframes), those artefacts (8×8 block boundaries, smoothing in the in-loop filter, chroma quantisation) get baked permanently into the PNG output — the conversion cannot un-quantise what the WebP encoder already discarded. Lossless WebP sources produce PNGs that match pixel-for-pixel. The PNG is essentially a 'compatibility wrapper' for whatever pixels the WebP decoded to — preserving the WebP's exact visual output at the cost of file size growth (typically 30–50% larger). Use this conversion when the destination genuinely cannot handle WebP (older Photoshop versions, certain print pipelines, archival systems with strict format whitelists); skip it when the destination already accepts WebP since the size penalty buys nothing useful in that case.

Source WebP decoded per RFC 9649 (lossy VP8 + lossless modes)
Output PNG per W3C 2nd Edition / ISO/IEC 15948:2004 with DEFLATE compression (RFC 1951)
Alpha channel preserved end-to-end (WebP ALPH chunk → PNG tRNS / RGBA, no flatten)
Lossless conversion from decoded WebP onward (no further quality loss)
Universal compatibility — every editor, OS, CMS, print pipeline reads PNG
Browser-side via WHATWG Canvas toBlob('image/png') — works in every modern browser including Safari

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Sources (5)

Zern, J., Massimino, P., & Alakuijala, J. (Google LLC) (2024). WebP Image Format. RFC 9649, IETF (November 2024, Informational) — source WebP container; lossy mode (VP8 keyframes), lossless mode (LZ77 + Huffman/prefix coding + colour cache); ALPH chunk for alpha (§2.7.1.2).
Bankoski, J., Koleszar, J., Quillio, L., Salonen, J., Wilkins, P., & Xu, Y. (Google Inc.) (2011). VP8 Data Format and Decoding Guide. RFC 6386, IETF (November 2011, Informational) — VP8 keyframe bitstream used by WebP lossy mode.
W3C (PNG Working Group) (2003). Portable Network Graphics (PNG) Specification (Second Edition). W3C Recommendation 10 November 2003 / ISO/IEC 15948:2004 — target lossless raster format with alpha channel preserved end-to-end from WebP source.
Deutsch, P. (1996). DEFLATE Compressed Data Format Specification version 1.3. RFC 1951, IETF (May 1996, Aladdin Enterprises — LZ77 + Huffman; PNG IDAT compression algorithm).
WHATWG (live). HTML Living Standard — Canvas 2D Context + HTMLCanvasElement.toBlob(). html.spec.whatwg.org/#2dcontext (browser conversion mechanism: decode WebP → toBlob('image/png'); WebP decoding is widely supported including Safari 14+ since 16 September 2020).

These are the W3C, ISO/IEC, ITU-T, and IETF specifications the tool implements or builds on. Locate them on w3.org, iso.org, itu.int, or datatracker.ietf.org.