8 explainers at 3,000 characters: MAI-Voice-2.1 $0.53 vs Sume $1.20

Eight explainer voiceovers of 3,000 characters each add up to 24,000 characters. At Microsoft's listed $22 per million characters, MAI-Voice-2.1 costs $0.528 before any rounding. MAI-Voice-2.1-Flash at $15 per million costs $0.36. On Sume TTS, which is $0.0475 per 1,000 characters and rounds each job up to the cent, eight jobs of $0.1425 become $0.15 each, $1.20 in all.

Microsoft's prices are from its October 1 announcement and Sume's from the Sume API reference (both read 2026-10-06).

What is the math?

Characters times the per-million rate, divided by one million. For Sume, each job is priced per transcript character, with spaces and punctuation counted, and the result is rounded up to a cent.

What does the gap pay for?

The Microsoft rows are model prices per character from the vendor's page. They are not the cost of running a pipeline. Sume's price covers an async job with an API key, hosted output files, word timings, sentence slices and the same job lifecycle as the other models. Whether that is worth the difference depends on whether you also need the avatar and timeline steps that follow.

What should I check before choosing?

Check which voices and languages each option has for your script, the licensing terms on the output, and the rate limits. Microsoft's page describes MAI-Voice-2.1 and Flash as available through Foundry, the MAI Playground, Vercel, OpenRouter and Azure Voice Live. Sume does not offer these models.