Deepgram Voice Agent API $0.075 a minute vs AssemblyAI $4.50 an hour

Two all-in voice agent APIs list the same price: Deepgram's standard Voice Agent tier is $0.075 per minute on pay as you go, and AssemblyAI's Voice Agent API is $4.50 an hour, which is also $0.075 a minute. Deepgram's advanced tier is $0.163 a minute. Neither includes anything Sume sells as a live product, because Sume has no live agent; its text-to-speech is about $0.036 to $0.038 per minute of speech and its speech-to-text is $0.01 a minute, both as file jobs.

Numbers are from Deepgram's pricing page and AssemblyAI's pricing page, both read on 2026-10-03. AssemblyAI's page lists what its rate covers; I did not see a comparable description of what Deepgram's tiers include beyond the label, so treat the comparison as price only.

The prices side by side

Per-hour figures are the per-minute price times 60.

What the pages say about the bundle

AssemblyAI describes its price as all-inclusive of STT, LLM reasoning, TTS, turn detection, interruption handling and tool calling. Deepgram lists the two tiers under Voice Agent API on the pay-as-you-go plan, and a separate Growth plan starting at $4K a year with pre-paid credits offering savings of up to 20 percent against pay-as-you-go rates. So the same $750 for 10,000 minutes could be lower on Deepgram at Growth volumes, by up to $150, if the 20 percent applies to this product; the page does not say which products the saving covers.

Setting Sume's lines beside them

Sume text to speech is $0.0475 per 1,000 characters, each quote rounded up to whole cents, up to 20,000 characters or 1,200 seconds of audio per request. Speech to text is $0.01 per minute of audio, up to 600 seconds per job.

Per-minute speech figures assume 750 to 800 characters a minute, the range Cartesia publishes for its voices; a script's real length varies with pace.

A minute of caller audio transcribed plus a minute of agent speech synthesized is $0.01 plus about $0.036 to $0.038, which is $0.046 to $0.048. That sits below the $0.075 bundle, but it leaves out the language model, turn-taking and any phone line, and it is delivered as a file, not a stream.

A support line

Take 2,000 calls a month averaging 4 minutes, 8,000 minutes. Deepgram standard and AssemblyAI both come to $600, and Deepgram advanced to $1,304. Transcribing every call afterwards on Sume STT, each under the 10-minute cap and so one job, is 2,000 x $0.04 = $80. That is a 13 percent addition on the $600 and gives you word-timed transcripts to search or caption, if the bundled product does not already provide a transcript you can use.

What Sume does and does not do

Sume does not hold a live conversation or stream audio in either direction. Use it for the assets and records around an agent.

• Render fixed greetings, hold messages and legal notices once. See pre-rendered greetings.
• Transcribe recordings after the call at $0.01 a minute, in 10-minute jobs.
• Compare stack costs with the voice agent cost breakdown.