Voice Agent Cost Calculator

A voice agent cost calculator estimates the total per-call and monthly infrastructure cost of running an AI-powered voice agent. Unlike simple API cost calculators, a voice agent involves a complete pipeline of four billable components: Speech-to-Text (STT) transcription, LLM inference for response generation, Text-to-Speech (TTS) synthesis, and telephony or WebRTC transport for the audio connection. Some deployments add a fifth layer — a voice agent platform like Vapi, Retell, or Bland AI — which charges a per-minute markup on top of component costs. Our voice agent cost calculator models all five layers with real provider pricing, giving you an accurate cost-per-call and monthly total. All calculations run locally in your browser with no data sent to any server.

1. Select a Use Case Preset: Choose from Customer Support, Sales Outbound, Appointment Booking, or Voice Assistant to load realistic provider combinations and call parameters. Or select Custom to configure every input manually.
2. Configure Your Voice Stack: Choose your STT provider (Deepgram, AssemblyAI, OpenAI Whisper, Google, AWS), LLM (GPT-4o Mini, Claude, Gemini, Groq, DeepSeek), TTS (ElevenLabs, Cartesia, Play.ht, OpenAI, AWS Polly), telephony carrier (Twilio, Telnyx, Daily.co, LiveKit), and optional orchestration platform.
3. Set Call Parameters: Enter your average call duration, daily call volume, LLM tokens per turn, conversation turns per call, and average TTS characters per response. The calculator automatically computes all cost components from these inputs.
4. Read Cost + Latency Results: Get per-call cost, per-minute cost, daily cost, monthly cost, and a full cost breakdown by layer with percentage contribution — plus a pipeline latency analyzer showing whether your stack meets the ≤500ms target for natural conversation.

• STT is billed per audio minute: Rates range from $0.002/min (AssemblyAI Nano) to $0.024/min (AWS Transcribe). For a 4-minute call at $0.004/min, STT costs $0.016/call — a relatively small share. Streaming (real-time) STT is required for low-latency voice agents; batch transcription is too slow for interactive use.
• LLM cost scales with turns and token length: Each conversational turn calls the LLM with the full conversation history in the prompt. At 8 turns × 800 input tokens × $0.15/M tokens = $0.00096 input cost per call. Output tokens are pricier but shorter in voice (typically 50–200 tokens). For high-quality models (GPT-4o, Claude Sonnet), LLM becomes the dominant cost.
• TTS is billed per character synthesized: ElevenLabs Flash charges $30/M chars. A 150-char agent response × 8 turns = 1,200 chars/call = $0.036/M × 1,200 = $0.000036/call — negligible. TTS cost only becomes significant at very high call volumes or with very verbose agents.
• Telephony and platform markups dominate at scale: Twilio at $0.0085/min for a 4-minute call = $0.034/call. Vapi adds $0.05/min = $0.20/call extra. At 500 calls/day, platform + telephony can exceed $100/day. Switching from Twilio to Telnyx ($0.002/min) or using a WebRTC transport saves significant money at volume.

Voice agents require a total pipeline latency of ≤500ms from end-of-speech detection to first audio byte reaching the caller. This consists of: STT latency (~150–400ms for streaming), LLM time-to-first-token (~150–600ms depending on model and provider), and TTS first-audio-byte latency (~75–400ms). The fastest stack available today — Deepgram Nova-3 + Groq Llama 3.1 + ElevenLabs Flash — achieves approximately 400–500ms total, enabling genuinely natural conversation. For less latency-sensitive use cases (appointment bots, IVR replacement), a 600–800ms pipeline is acceptable. Use this voice agent cost calculator to find the cheapest provider combination that still hits your latency target. All inputs process 100% locally — your data never leaves your device.