Voice AI Cost Calculator
Estimate your voice AI infrastructure costs. Compare orchestration (STT → LLM → TTS) vs. speech-to-speech workflows across providers.
Last updated: June 13, 2026
Usage
Total inbound + outbound calls
Typical: 0.5 (receptionist) to 15 (interview)
Default 5,000. Includes instructions, persona, tools.
Providers
All LLM Options Compared
Using AssemblyAI Streaming (STT) + Speechify API (TTS). LLM cost includes 50% tool-calling overhead.
| Model | LLM Cost | Total/mo | Per Call |
|---|---|---|---|
| Gemini 2.0 FlashCheapest | $1.69 | $101.69 | $0.10 |
| Gemini 2.5 Flash-Lite | $1.69 | $101.69 | $0.10 |
| OpenAI GPT-4.1 nano | $3.38 | $103.38 | $0.10 |
| OpenAI GPT-5.4 nano | $4.22 | $104.22 | $0.10 |
| OpenAI GPT-4o mini | $5.06 | $105.06 | $0.11 |
| Gemini 3.1 Flash-Lite | $5.16 | $105.16 | $0.11 |
| Gemini 2.5 Flash | $7.50 | $107.50 | $0.11 |
| Gemini 3 Flash | $10.31 | $110.31 | $0.11 |
| OpenAI GPT-4.1 mini | $13.50 | $113.50 | $0.11 |
| Claude Haiku 3.5 | $15.00 | $115.00 | $0.12 |
| OpenAI GPT-5.4 mini | $15.47 | $115.47 | $0.12 |
| Claude Haiku 4.5 | $18.75 | $118.75 | $0.12 |
| Gemini 3.1 Pro | $41.25 | $141.25 | $0.14 |
| OpenAI GPT-4.1 | $50.63 | $150.63 | $0.15 |
| OpenAI GPT-5.4 | $51.56 | $151.56 | $0.15 |
| Claude Sonnet 4.6 | $56.25 | $156.25 | $0.16 |
| OpenAI GPT-4o | $63.28 | $163.28 | $0.16 |
| Claude Opus 4.6 | $93.75 | $193.75 | $0.19 |
| Claude Opus 4.8 | $93.75 | $193.75 | $0.19 |
| Claude Fable 5 | $187.50 | $287.50 | $0.29 |
Monthly Cost Estimate
Assumptions: 250 tokens/min conversation rate, 1:1 speaker split, 50% tool-calling overhead on LLM, system prompt sent once per call. Actual costs vary by conversation complexity.
Quick scenarios
Frequently Asked Questions
How much does a voice AI agent cost per call?
It depends on call duration, workflow (orchestration vs. speech-to-speech), and provider choices. The main cost drivers are STT minutes, LLM tokens, and TTS minutes; a short call on budget providers costs a few cents, while a long call with a premium voice costs considerably more. The calculator computes per-call and per-1,000-call costs from current provider rates for your call profile.
What is the difference between orchestration and speech-to-speech?
Orchestration (STT → LLM → TTS) uses separate providers for speech recognition, language model processing, and voice synthesis. This gives you flexibility to mix providers and optimize costs. Speech-to-speech uses a single realtime model (like OpenAI Realtime or Gemini Flash Live) that handles audio natively: simpler to build, but currently more expensive per token.
Which TTS provider is cheapest for voice AI?
As of the calculator's last-verified pricing, Speechify API is the cheapest TTS it tracks at $0.0075 per minute, with OpenAI tts-1 and Deepgram Aura-1 at $0.011/min. Voice quality varies significantly: Cartesia Sonic ($0.029/min) and ElevenLabs ($0.135/min) offer more natural-sounding voices at a higher price. With premium voices, TTS is often the largest line item in a voice AI stack.
How are tokens calculated for voice AI?
For each call, the system prompt is sent once (typically 2,000-5,000 tokens), and the conversation then generates roughly 250 tokens per minute, split between input (caller speech transcribed) and output (agent response). At scale, a 10-minute call with a 5,000-token prompt works out to about 6.25M input tokens and 1.25M output tokens per 1,000 calls.