Cartesia vs OpenAI TTS
Discover key differences between Cartesia and ElevenLabs voice AI models.
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Compare Cartesia and OpenAI TTS Voice Models
Explore the differences between Cartesia and OpenAI TTS voice models. Discover features, pricing, and performance metrics.
Updated at:
Feb 14, 2025
Features
Cartesia
90 ms + network time
Consistently rated as more natural, expressive, and realistic in blinded human evaluations
Infinite request length
Requires 5-10 seconds of audio
IPA Support, strong contextual understanding
Slider control for speed and emotion + synthetic voice mixing and design
8kHz audio, telephony optimized voices
Real-time generation on-device
15 languages with extensive dialect coverage
Up to 15 on highest self serve tier, custom for enterprise
OpenAI Speech to Text
200 ms + network time, slower response times
Lower quality ratings in human evaluations, and limited emotional control
Limited character count for longer texts
Requires 15 seconds of audio
Requires 60 minutes of audio
Less contextual awareness in pronunciation
Basic controls for speed, emotion and similarity
Standard audio quality without optimization
No on-device generation available
57
3-200 per mins
Latency
We measure latency using the Time to First Audio (TTFA) metric and calculate the 90th percentile score from 100 TTFA measurements for each provider. With a TTFA of 199 ms, Cartesia's Sonic model is significantly faster than ElevenLabs' 832 ms at the self-serve tier (with ElevenLabs reserving slightly lower latency for enterprise customers). Cartesia’s Sonic model is built on a radically more efficient architecture, known as State Space Models (SSMs), which allows for far greater latency optimization than the traditional transformer architecture used by ElevenLabs and other providers. For a side by side comparison, watch the latency demonstration in this video on X.
Pronunciation Accuracy
Using the Time to First Audio (TTFA) metric, Cartesia's Sonic model achieves a TTFA of 199 ms, significantly faster than ElevenLabs' 832 ms. This efficiency is due to Cartesia's advanced State Space Models (SSMs), optimizing latency beyond traditional architectures.
Voice Cloning
Cartesia provides unlimited instant voice cloning. In contrast, ElevenLabs restricts cloning capabilities with tiered plans allowing for 10, 30, 160, or 660 custom voices. Additionally, Cartesia utilizes advanced embedding technology to deliver consistent, high-quality voice clones. Cartesia preserves accents and voice quality even if the original audio clip is noisy. Cartesia's voice mixing and design capabilities also open up a more comprehensive set of diverse voices. In the following samples of Engelbart's clones, it's apparent that Cartesia produces a significantly less noisy and higher quality clone than ElevenLabs.
Voice Design Controllability
Cartesia stands out as the only provider offering emotion and speed modulation features, enabling refined voice adjustments while preserving a natural and seamless auditory experience. Cartesia also allows you to localize the voice to match different accents — you can start with an American voice and have it speak in a French accent, for instance. In comparison, ElevenLabs only offers controls for stability, similarity, and style exaggeration, all of which do not offer clear control for the voice. In the following example where the speaker is addressing a customer complaint, we compare the dial effects from ElevenLabs and Cartesia to find that the ElevenLabs voice sounds similar with the various dials applied while Cartesia's emotion and speed dials convey very noticeable changes.
Cartesia - Advanced AI Voice Capabilities
Cartesia AI offers the fastest voice model with hallucination-free, ultra-realistic voice generation and cloning.
Voice Clone
Cartesia's voice cloning delivers lifelike, accurate voice replication with unmatched fidelity.
Ultra-Realistic Voices
With a time-to-first-audio of just 90ms, Sonic provides the fastest and most realistic voice generation available.
No Hallucinations
Cartesia's AI text to speech eliminates errors, ensuring authentic and clear audio output every time.
Pricing Plans for Cartesia and ElevenLabs
Cartesia
Free - $0/mo. per month with 10k free credits
Pro - $5/mo. per month with 100k credits
Startup - $49/mo. per month with 1.25M credits
Scale - $299/mo. per month with 8M credits
Enterprise - trusted by Fortune 500 companies
OpenAI Speech to Text
TTS - $15 per 1M characters
TTS HD - $30 per 1M characters
What Cartesia customers say
Join the growing list of companies opting for Sonic.
"This partnership represents a transformative moment in enterprise AI adoption," said Melissa Gordon, CEO of Rasa. "By combining Rasa’s strengths in enterprise conversational AI with Cartesia's innovative voice technology, we're fundamentally changing how enterprises can deploy and scale AI assistants across their organizations."
"We're thrilled to partner with Cartesia - their technology has dramatically improved the accuracy and reliability of our call center agents. Beyond just providing best-in-class voice AI, the Cartesia team has been a true partner in helping us transform 24/7 patient support for over 215,000 patients. Their support has been instrumental in making exceptional care accessible anytime, anywhere."
Jeffrey Liu, Founder and co-CEO, Assort Health
"Together AI's mission has always been to provide developers with the most powerful and efficient tools for building AI applications," says Vipul Ved Prakash, Together AI's CEO. "Cartesia is leading the charge of building efficient, multimodal models from first principles, starting with their Sonic TTS model. By integrating Sonic into our platform, we're enabling developers to create sophisticated multi-modal applications that leverage the most advanced and lowest latency voice model available today, all while maintaining the simplicity and reliability our users expect."
