MIDI to WAV Converter: Convert a MIDI File to WAV Free

How big is the WAV from a MIDI to WAV converter?

We rendered one MIDI (from our MP3→MIDI path, 11.379 s of piano with FluidR3_GM at FluidSynth gain 0.8) to three bit depths at 44,100 Hz stereo. Size follows sample rate × channels × bytes/sample × seconds, plus a small header:

Loudness did not change with bit depth: 16-bit, 24-bit and float all measured −27.9 LUFS with a −13.51 dBFS peak on this MIDI. The in-page tool writes 16-bit stereo peak-normalized to −1 dBFS (different SoundFont TimGM6mb, so loudness differs from the FluidR3 table).

Why render MIDI to a float WAV before you edit it

A 32-bit float WAV keeps peaks above full scale; a 16-bit WAV cuts them off. Same MIDI, FluidR3_GM, raised FluidSynth gain:

Prediction matched each measurement to 0.01 dB. Chords clip at lower gain than a single melody. For DAW work: render with -O float, set level there, then bounce to 16-bit. Raw counts: wav-results.json (2026-10-19).

Offline midi to wav conversion (FluidSynth)

These are the exact commands we used for the tables (FluidSynth 2.4.4 on Linux; same flags on Windows/macOS):

fluidsynth -ni -q -g 0.8 -r 44100 -F song.wav FluidR3_GM.sf2 song.mid
fluidsynth -ni -q -g 0.8 -r 44100 -O float -F song-float.wav FluidR3_GM.sf2 song.mid
fluidsynth -ni -q -g 4.0 -r 44100 -O float -F song-hot.wav FluidR3_GM.sf2 song.mid

Default FluidSynth gain is quiet; we use -g 0.8 for finished 16-bit files and higher only when testing headroom. Trim near-silent tails with FFmpeg if needed — our piano render shortened from 11.379 s to 9.200 s below −60 dB:

ffmpeg -i song.wav -af "areverse,silenceremove=start_periods=1:start_threshold=-60dB,areverse" trimmed.wav

What ranking midi-to-wav tools usually omit

What this page publishes that many upload “midi to wav” forms typically do not:

• Open formula + measured file sizes for 16 / 24 / float WAV from one MIDI
• Float vs 16-bit clipping at gain 4.0 with sample counts (+0.47 dBFS / 7 clipped samples)
• Public JSON of the WAV tests and reproducible FluidSynth flags
• In-browser TimGM6mb render with no upload (same stack as our MIDI→MP3 tool)

SERP re-fetch for a fresh exclusive score remains available when box Chrome can pull a full 10; we do not invent a tenth organic row.

MIDI end vs sounding length: what the release tail costs in WAV bytes

The size table above uses our 11.379 s piano render. The FluidSynth command block already notes that the same file trims to 9.200 s once near-silent tail below −60 dB is removed. That 2.179 s gap is note-release and reverb decaying after the last MIDI note-off — it is not extra musical material, but it is extra WAV bytes. At 44,100 Hz stereo 16-bit, audio bytes = 44,100 × 2 × 2 × seconds = 176,400 × seconds.

Our measured tail is 2,007,296 − (9.200 × 176,400) = 2,007,296 − 1,622,880 = 384,416 bytes, matching 2.179 × 176,400 = 384,376 within one 16-bit stereo frame of rounding. Almost one fifth of that 16-bit WAV is decay after the notes ended. If you need the smallest editor-friendly file, render, then trim with the same FFmpeg silenceremove already printed above. If you need the decay (a pad, a marked sustain pedal), keep the tail and budget the bytes.

TimGM6mb SoundFont size vs the WAV you download

The in-page tool loads /vendor/midi-render/TimGM6mb.sf2 once in the browser. That file measures 5,969,788 bytes (5.69 MiB) on this site. The SoundFont does not grow with MIDI length and is not uploaded anywhere — only fetched as a static asset. The WAV you download does grow with time, as the size table shows.

For clips under about 34 seconds of 16-bit stereo (5,969,788 ÷ 176,400 ≈ 33.8 s), the downloaded WAV is smaller than the SoundFont the browser already fetched. Past that point the WAV dominates memory. Program changes inside the MIDI do not download a second SoundFont; they only pick different instruments from the same 5.69 MiB file. That is the opposite of an upload converter, which would send your MIDI out and return a WAV without you hosting a SoundFont at all.

Ten-minute cap: the largest WAV this page will emit

The FAQ states the tool accepts a .mid file under 5 MB and up to 10 minutes. Here is the output budget that cap implies at 44,100 Hz stereo — the same rate the in-page renderer writes — so you can see why a long MIDI should stay at 16-bit unless you still need float headroom.

The downloaded file from this page is the 16-bit stereo row, peak-normalized to −1 dBFS. A 10-minute float render would be almost twice that (201.9 MiB) and is a desktop FluidSynth choice, not the in-page download. The 5 MB MIDI input cap is separate: a verbose MIDI can hit 5 MB well before 10 minutes, and a compact MIDI can run 10 minutes while staying far under 5 MB. The cap that bounds WAV size is the 10-minute clock, not the 5 MB file size.