Measured on our servers

Conversion Speed & Quality Index

Real, measured numbers — conversion speed, how much the file grows or shrinks, and the quality trade — for 91 of the most popular conversions. No estimates: every figure comes off our own engine, with the method stated below.

conversions measured

Video conversions

Conversion	Speed	Output size change
3GP to MP4	Fast	~50% smaller	Convert
AVI to MP3	Instant	~97% smaller	Convert
AVI to MP4	Fast	varies	Convert
FLV to MP4	Fast	varies	Convert
GIF to JPG	Instant	varies	Convert
GIF to MP4	Instant	~62% smaller	Convert
GIF to PNG	Instant	~98% smaller	Convert
GIF to WebP	Fast	~18% smaller	Convert
M4V to MP4	Instant	unchanged	Convert
MKV to AVI	Fast	grows	Convert
MKV to MP3	Instant	~94% smaller	Convert
MKV to MP4	Instant	unchanged	Convert
MOV to AVI	Fast	grows	Convert
MOV to GIF	Fast	grows	Convert
MOV to MP3	Instant	~94% smaller	Convert
MOV to MP4	Instant	unchanged	Convert
MP4 to AVI	Fast	varies	Convert
MP4 to GIF	Fast	grows	Convert
MP4 to MOV	Instant	unchanged	Convert
MP4 to MP3	Instant	~95% smaller	Convert
MP4 to WAV	Fast	grows	Convert
MP4 to WebM	Heavier	varies	Convert
MPEG to MP4	Fast	varies	Convert
MTS to MP4	Instant	unchanged	Convert
OGV to MP4	Heavier	~22% smaller	Convert
TS to MP4	Instant	unchanged	Convert
VOB to MP4	Fast	~86% smaller	Convert
WebM to GIF	Instant	~64% smaller	Convert
WebM to MP3	Instant	~80% smaller	Convert
WebM to MP4	Fast	grows	Convert
WMV to MP4	Fast	grows	Convert

Audio conversions

Conversion	Speed	Output size change
AAC to MP3	Instant	varies	Convert
AC3 to MP3	Fast	unchanged	Convert
AMR to MP3	Instant	~37% smaller	Convert
FLAC to MP3	Heavier	~62% smaller	Convert
FLAC to WAV	Instant	grows	Convert
M4A to MP3	Instant	varies	Convert
MP3 to MP4	Heavier	~30% smaller	Convert
MP3 to OGG	Fast	~93% smaller	Convert
MP3 to WAV	Instant	grows	Convert
OGG to MP3	Instant	grows	Convert
Opus to MP3	Instant	grows	Convert
WAV to MP3	Instant	varies	Convert
WMA to MP3	Instant	varies	Convert

Image conversions

Conversion	Speed	Output size change
AVIF to JPG	Instant	grows	Convert
AVIF to PNG	Heavier	grows	Convert
BMP to JPG	Instant	~91% smaller	Convert
BMP to PNG	Instant	~86% smaller	Convert
EPS to JPG	Fast	~96% smaller	Convert
EPS to PNG	Heavier	~79% smaller	Convert
HEIC to JPG	Instant	grows	Convert
HEIC to PNG	Heavier	grows	Convert
JPG to PDF	Instant	varies	Convert
JPG to PNG	Instant	grows	Convert
JPG to SVG	Instant	~87% smaller	Convert
JPG to WebP	Instant	~60% smaller	Convert
PNG to ICO	Instant	varies	Convert
PNG to JPG	Instant	~65% smaller	Convert
PNG to PDF	Instant	~42% smaller	Convert
PNG to SVG	Instant	~99% smaller	Convert
PNG to WebP	Instant	~93% smaller	Convert
PSD to JPG	Instant	~98% smaller	Convert
PSD to PNG	Fast	~60% smaller	Convert
SVG to JPG	Instant	grows	Convert
SVG to PNG	Instant	grows	Convert
TGA to PNG	Fast	~64% smaller	Convert
TIFF to JPG	Instant	~95% smaller	Convert
TIFF to PDF	Instant	~41% smaller	Convert
TIFF to PNG	Fast	~24% smaller	Convert
WebP to GIF	Fast	grows	Convert
WebP to JPG	Instant	grows	Convert
WebP to PDF	Instant	grows	Convert
WebP to PNG	Fast	grows	Convert

spreadsheet conversions

Conversion	Speed	Output size change
CSV to XLSX	Instant	grows	Convert
XLSX to CSV	Instant	~79% smaller	Convert
XLSX to PDF	Instant	grows	Convert

Document conversions

Conversion	Speed	Output size change
DOC to DOCX	Fast	~78% smaller	Convert
DOC to PDF	Instant	grows	Convert
DOCX to PDF	Instant	grows	Convert
HTML to PDF	Fast	grows	Convert
ODT to DOCX	Instant	~16% smaller	Convert
ODT to PDF	Fast	grows	Convert
PDF to DOCX	Fast	~77% smaller	Convert
PDF to JPG	Instant	grows	Convert
PDF to PNG	Instant	grows	Convert
PDF to PPTX	Instant	~80% smaller	Convert
PDF to TXT	Instant	~93% smaller	Convert
RTF to PDF	Instant	grows	Convert

eBook conversions

Conversion	Speed	Output size change
EPUB to MOBI	Fast	grows	Convert
MOBI to EPUB	Fast	~18% smaller	Convert

presentation conversions

Conversion	Speed	Output size change
PPTX to PDF	Instant	unchanged	Convert

How we measured this

Each conversion was run on our production worker (the same engine that powers the live tools) in June 2026. Speed is wall-clock time on a representative source file — a 10-second 1280×720 clip for video, a 3-minute track for audio, a 1920×1080 image, or a short document. Output-size change is the converted file versus the source. Figures are indicative: real timing and size depend on your file's length, resolution and source bitrate.

Looking for compression specifically? See our File Compression Benchmark 2026.