F5-TTS vs Cartesia Sonic: Which AI Model Should You Choose?
Pricing, context windows, latency, capabilities, and a one-line code switch — everything you need to pick the right model.
F5-TTS and Cartesia Sonic are closely matched on pricing and context. The right choice depends on your specific workload — see the table below for the full breakdown.
Side-by-side specs
| Spec | F5-TTS | Cartesia Sonic |
|---|---|---|
| Provider | Replicate | xAI |
| Category | Text-to-Speech | Text-to-Speech |
| Input cost / 1M tokens | Free | €0.030 |
| Output cost / 1M tokens | Free | Free |
| Context window | — | — |
| Max output tokens | — | — |
| Avg. latency | — | — |
| Featured | — | — |
| New | — | — |
| Capabilities | text audio | text |
Pricing example
A typical chat workload of 100,000 input tokens plus 50,000 output tokens.
100K in × Free + 50K out × Free
100K in × €0.030 + 50K out × Free
For this workload, F5-TTS is cheaper than Cartesia Sonic by €0.0030 per request.
Switch in one line
Both models live behind Railwail's OpenAI-compatible endpoint. Replace the model string and you are done.
import OpenAI from "openai";
const client = new OpenAI({
apiKey: process.env.RAILWAIL_API_KEY,
baseURL: "https://railwail.com/v1",
});
// Before — using F5-TTS
let r = await client.chat.completions.create({
model: "SWivid/F5-TTS",
messages: [{ role: "user", content: "Hello" }],
});
// After — switched to Cartesia Sonic
r = await client.chat.completions.create({
model: "sonic",
messages: [{ role: "user", content: "Hello" }],
});from openai import OpenAI
client = OpenAI(
api_key=os.environ["RAILWAIL_API_KEY"],
base_url="https://railwail.com/v1",
)
# Before — using F5-TTS
r = client.chat.completions.create(
model="SWivid/F5-TTS",
messages=[{"role": "user", "content": "Hello"}],
)
# After — switched to Cartesia Sonic
r = client.chat.completions.create(
model="sonic",
messages=[{"role": "user", "content": "Hello"}],
)# Before — using F5-TTS
curl https://railwail.com/v1/chat/completions \
-H "Authorization: Bearer $RAILWAIL_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "SWivid/F5-TTS",
"messages": [{"role": "user", "content": "Hello"}]
}'
# After — switched to Cartesia Sonic
curl https://railwail.com/v1/chat/completions \
-H "Authorization: Bearer $RAILWAIL_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "sonic",
"messages": [{"role": "user", "content": "Hello"}]
}'Which one wins for...
Quick verdicts derived from public specs. Always validate on your own workload.
Higher coding category match or larger context wins.
Bigger context window helps maintain long-form coherence.
The larger context window is the deciding factor.
Multimodal/vision support is required for image inputs.
Lower average latency wins for interactive UX.
The model with the lower input-token price wins.
Frequently asked questions
Try F5-TTS and Cartesia Sonic side by side
One API key, one endpoint, both models. Start free — no credit card required.