Speech-to-Text API Cost Ranking
Every provider ranked by cost for a typical workload: 300 minutes/day, async batch processing.
Top Picks by Volume
Small Project (under $15/month)
Deepgram Nova-2$38.70/mo
OpenAI Whisper$54.00/mo
AssemblyAI Async$76.50/mo
Business ($50-200/month)
Deepgram Nova-2$258/mo (1K min/day)
OpenAI Whisper$360/mo
AssemblyAI Async$510/mo
Enterprise Volume ($500+/month)
Deepgram Nova-2$1,296/mo (5K min/day)
OpenAI Whisper$1,800/mo
Google Cloud STT$2,880/mo
Strategy: Async + Realtime Hybrid
Use a hybrid approach — async processing for recorded content, real-time for live applications.
Smart STT Pipeline (500 min/day)
70% recordings → Deepgram async ($0.0043/min)$45.15/mo
30% live calls → Deepgram realtime ($0.0077/min)$34.65/mo
Total with hybrid$79.80/mo (vs $135 using realtime for everything)
The hybrid approach saves 41% compared to using real-time processing for all audio. Most recorded content can be processed asynchronously at lower cost.
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Open Savings Calculator →Key Factors When Choosing an STT API
- Per-minute pricing: STT APIs charge per minute of audio processed. Async (batch) is 40-60% cheaper than real-time streaming. If you don't need instant results, always use async.
- Accuracy matters more than price: A 1% accuracy improvement can save hours of manual correction. Deepgram Nova-2 and OpenAI Whisper lead in accuracy benchmarks. The cheapest option isn't always the best value if accuracy is poor.
- Speaker diarization: For meetings and multi-speaker content, speaker diarization (who said what) is essential. Deepgram, AssemblyAI, and Google all offer this. It may cost extra ($0.01-0.02/min additional).
- Language support: OpenAI Whisper supports 100+ languages. Deepgram focuses on English and major European/Asian languages. Google Cloud STT has the broadest language coverage. Choose based on your target languages.
- Custom vocabulary: For technical, medical, or industry-specific content, custom vocabulary support improves accuracy. AssemblyAI and Google have the best custom vocabulary options.
- File size limits: Some APIs limit audio file length (e.g., 25MB for OpenAI Whisper API). For long recordings, use chunked uploads or choose a provider with no file size limits (Deepgram, Google).
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