Question 1

How is voice AI pricing calculated?

Accepted Answer

Most TTS providers charge per character of input text. OpenAI charges $15 per 1M characters, ElevenLabs charges $30 per 1M characters.

Question 2

What is the cheapest voice AI API?

Accepted Answer

Deepgram Aura at $12 per 1M characters is the cheapest production option. Gemini TTS is free during preview.

Question 3

How many characters is a typical conversation?

Accepted Answer

A typical customer service interaction is 500-2,000 characters per response. A 5-minute conversation generates roughly 5,000-10,000 characters total.

Question 4

Should I use per-character or per-minute pricing?

Accepted Answer

Most TTS APIs use per-character pricing because it is predictable. For budgeting, assume ~150 words per minute of speech, which is ~750-900 characters.

Question 5

What about STT (speech-to-text) costs?

Accepted Answer

STT pricing is separate and typically cheaper. Deepgram charges $0.0043/min, Google charges $0.016/min, Azure charges $0.01/min. A full voice agent needs both STT and TTS.

Voice AI Pricing Comparison (2026)