OpenAI vs AssemblyAI pricing
STT: OpenAI from $0.003 vs AssemblyAI from $0.0025.
Last updated · prices checked daily
Speech-to-text: OpenAI vs AssemblyAI
AssemblyAI has the lower listed STT price: $0.0025 per minute (Universal-Streaming (English)) vs $0.003 for OpenAI (gpt-4o-mini-transcribe (estimated)), about 17% less.
| Vendor | Product / tier | $/min |
|---|---|---|
| AssemblyAI Visit site ↗ | Universal-Streaming (English) | $0.0025 |
| AssemblyAI Visit site ↗ | Universal-2 (pre-recorded) | $0.0025 |
| OpenAI Visit site ↗ | gpt-4o-mini-transcribe (estimated) Token-billed; OpenAI's own per-minute estimate. | $0.003 |
| AssemblyAI Visit site ↗ | Universal-3.5 Pro (pre-recorded) | $0.0035 |
| OpenAI Visit site ↗ | gpt-transcribe (batch) | $0.0045 |
| OpenAI Visit site ↗ | gpt-live-transcribe (streaming) | $0.017 |
What it costs at volume (lowest listed rate)
| Minutes | OpenAI | AssemblyAI |
|---|---|---|
| 1,000 min | $3.00 | $2.50 |
| 10,000 min | $30.00 | $25.00 |
| 100,000 min | $300.00 | $250.00 |
Cost-per-call calculator
Estimate what one call really costs. Prices come from today's table; LLM and telephony presets are per-minute rates published by Retell and Vapi. Everything is editable.
Cartesia's pricing page puts one minute of speech at 750–800 characters; Rime says about 1,000. The talk share is your own guess at how much of each call the agent is speaking.
FAQ
Is OpenAI or AssemblyAI cheaper for speech-to-text?
AssemblyAI has the lower listed STT price: $0.0025 per minute (Universal-Streaming (English)) vs $0.003 for OpenAI (gpt-4o-mini-transcribe (estimated)), about 17% less. Prices checked Oct 28, 2026.
How often are these prices updated?
Every day. A script reads each vendor's public pricing page, extracts the listed rates and keeps a dated copy, so price changes show up in the history.