OpenLuxClaude Sonnet 4.5 vs Claude Fable 5.1
Claude Sonnet 4.5 and Claude Fable 5.1 both run on OpenLux behind one OpenAI-compatible endpoint. Claude Sonnet 4.5 is metered at $0.2647 per 1M tokens (-91% vs official rates); Claude Fable 5.1 at $1.765 per 1M tokens (-82% vs official rates). Claude Sonnet 4.5 is the lower-cost option per unit — about 85% cheaper on the same OpenLux endpoint. This page compares their rates, strengths and best-fit workloads so you can route each request to the right model.
The short version
In practice the two models are complements, not substitutes: Claude Sonnet 4.5 suits workloads that need agents and apps that call tools or functions, prompts that include images, charts or screenshots. Claude Fable 5.1 is the better fit when you need agents and apps that call tools or functions, prompts that include images, charts or screenshots. Both are called with the same OpenLux key, so switching between them is a one-field change to the model name.
Choose Claude Sonnet 4.5 when
- You need agents and apps that call tools or functions.
- You need prompts that include images, charts or screenshots.
- Unit cost is the deciding factor for this workload.
Choose Claude Fable 5.1 when
- You need agents and apps that call tools or functions.
- You need prompts that include images, charts or screenshots.
Rates on OpenLux
| Model | Provider | Rate | Discount |
|---|---|---|---|
| Claude Sonnet 4.5 | Anthropic | $0.2647 per 1M tokens | -91% |
| Claude Fable 5.1 | Anthropic | $1.765 per 1M tokens | -82% |
Rates follow official provider pricing and are billed in USD. See the full catalogue and pricing plans for credit allowances.
One snippet, two models
Claude Sonnet 4.5 and Claude Fable 5.1 share the same OpenAI-compatible request shape. Run the same code against both and compare the answers on your own workload.
from openai import OpenAI
client = OpenAI(
api_key="sk-openlux-...",
base_url="https://openlux.lol/v1",
)
for model in ["claude-sonnet-4-5-20250929", "claude-fable-5-1"]:
resp = client.chat.completions.create(
model=model,
messages=[{"role": "user", "content": "Summarise this release note for me."}],
)
print(model, "->", resp.choices[0].message.content)Any OpenAI SDK works the same way — see the docs for streaming, tools and error codes.
Claude Sonnet 4.5 vs Claude Fable 5.1 questions
How much do Claude Sonnet 4.5 and Claude Fable 5.1 cost on OpenLux?
Claude Sonnet 4.5 is metered pay as you go at $0.2647 per 1M tokens, a -91% discount on official list pricing. Claude Fable 5.1 is metered at $1.765 per 1M tokens, a -82% discount. There is no subscription requirement: usage is billed in USD and every request is visible in the console.
Can I call Claude Sonnet 4.5 and Claude Fable 5.1 with the same API key?
Yes. Both models sit behind the same OpenAI-compatible endpoint at https://openlux.lol/v1. Keep the same key and change only the "model" field to switch between claude-sonnet-4-5-20250929 and claude-fable-5-1 — request and response shapes stay identical.
Which is cheaper, Claude Sonnet 4.5 or Claude Fable 5.1?
Claude Sonnet 4.5 costs less per unit: $0.2647 per 1M tokens versus $1.765 per 1M tokens, about 85% lower for the same volume. Over a month of production traffic the difference compounds, and the console shows cost per request in real time.
When should I pick Claude Sonnet 4.5 over Claude Fable 5.1?
In practice the two models are complements, not substitutes: Claude Sonnet 4.5 suits workloads that need agents and apps that call tools or functions, prompts that include images, charts or screenshots. Claude Fable 5.1 is the better fit when you need agents and apps that call tools or functions, prompts that include images, charts or screenshots. Both are called with the same OpenLux key, so switching between them is a one-field change to the model name.
Keep comparing
More head-to-head pages that pair well with this one.
GPT-6 Astra vs Claude Sonnet 4.5
Rates, strengths and which model to pick.
GPT-5.6 Sol vs Claude Sonnet 4.5
Rates, strengths and which model to pick.
Gemini 3.8 Flash vs Claude Sonnet 4.5
Rates, strengths and which model to pick.
Gemini 3 Flash (preview) vs Claude Sonnet 4.5
Rates, strengths and which model to pick.
Claude Sonnet 4.5 vs Claude Opus 5
Rates, strengths and which model to pick.
Claude Sonnet 4.5 vs Gemini 3.1 Pro (preview)
Rates, strengths and which model to pick.
Explore by use case
Tool calling & agents
Every Tools-capable model, ready for function calling and agent loops.
Cheapest text models
The lowest per-token rates for volume chat and automation.
Biggest discounts
The largest gaps between official list prices and OpenLux rates.
Chinese-optimized models
DeepSeek, Qwen and Doubao for Chinese-language products.
Route every request to the right model
OpenLux keeps Claude Sonnet 4.5, Claude Fable 5.1 and every other model behind one key, one endpoint and one bill. Start with free trial credit and switch models without touching your code.