Apple Silicon has made local AI transcription practical. OpenAI's Whisper, which once required powerful GPUs, now runs smoothly on MacBooks and Mac minis. But how fast is it really? And which Whisper model should you use with your specific chip?
We benchmarked Whisper across the Apple Silicon lineup to give you real-world performance data.
Understanding Whisper Model Sizes
Whisper comes in several sizes. Larger models are more accurate but require more processing power:
| Model | Parameters | RAM Required | Relative Accuracy |
|---|---|---|---|
| Tiny | 39M | ~1 GB | Good for drafts |
| Base | 74M | ~1 GB | Decent accuracy |
| Small | 244M | ~2 GB | Good accuracy |
| Medium | 769M | ~5 GB | Very good accuracy |
| Large | 1.5B | ~10 GB | Best accuracy |
Recommendation: For most users, the Medium model offers the best balance of accuracy and speed on Apple Silicon. It's what Voicci uses by default.
Real-World Benchmarks
We transcribed a 10-minute audio file (clear speech, single speaker) using the Medium model across different Macs. Speed is measured as "real-time factor" (RTF) — lower is faster.
| Mac | Chip | RAM | Time (10 min audio) | RTF |
|---|---|---|---|---|
| MacBook Air | M1 | 8 GB | ~3 min | 0.3x |
| MacBook Pro 14" | M1 Pro | 16 GB | ~2 min | 0.2x |
| MacBook Air | M2 | 8 GB | ~2.5 min | 0.25x |
| MacBook Pro 14" | M3 Pro | 18 GB | ~1.5 min | 0.15x |
| MacBook Pro 16" | M3 Max | 36 GB | ~1 min | 0.1x |
| Mac mini | M4 | 16 GB | ~1.2 min | 0.12x |
| MacBook Pro 14" | M4 Pro | 24 GB | ~50 sec | 0.08x |
What This Means For You
M1 / M2 (Base Chips)
Absolutely usable for transcription. A 10-minute audio file takes about 2-3 minutes. For real-time dictation, expect slight delays between speaking and seeing text.
Recommended model: Medium (or Small if you have only 8 GB RAM and need speed)
M1 Pro / M2 Pro / M3
Sweet spot for most users. Transcription feels snappy, and real-time dictation works smoothly with minimal delay.
Recommended model: Medium (or Large if you prioritize accuracy)
M3 Pro / M3 Max / M4 / M4 Pro
Transcription is essentially instant. You can run the Large model comfortably for maximum accuracy, and real-time dictation has no perceptible delay.
Recommended model: Large for maximum accuracy
RAM Matters
Whisper model size affects RAM usage significantly:
- 8 GB Mac: Tiny, Base, Small models work well. Medium is tight but usable.
- 16 GB Mac: All models up to Large work comfortably.
- 24+ GB Mac: Run Large model while multitasking without slowdown.
If you're on an 8 GB Mac and experience slowdowns with Medium, drop to Small. The accuracy difference is modest, and the speed improvement is significant.
Real-Time Dictation vs. File Transcription
The benchmarks above are for transcribing audio files. Real-time dictation (speaking and seeing text appear) has different requirements:
- File transcription: Can be slower than real-time and still feel "instant"
- Real-time dictation: Needs RTF below ~0.3x to feel responsive
Every Apple Silicon Mac handles real-time dictation adequately. The difference is in how much delay you experience between speaking and seeing text.
Bottom Line
Any Apple Silicon Mac can run Whisper effectively. M1 is the floor — it works well. M3/M4 chips are overkill for transcription (but you'll enjoy the speed). The Medium model is the sweet spot for accuracy vs. performance on most setups.
Optimizing Performance
A few tips to get the best transcription speed:
- Close memory-hungry apps: Whisper benefits from available RAM
- Use the right model size: Bigger isn't always better for your hardware
- Keep macOS updated: Apple continually optimizes Metal performance
- Use an app optimized for Apple Silicon: Native apps like Voicci leverage the Neural Engine properly
Experience Fast, Private Voice-to-Text
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