OpenLuxClaude Sonnet 4.5 vs Claude Opus 5
Claude Sonnet 4.5 and Claude Opus 5 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 Opus 5 at $0.4412 per 1M tokens (-91% vs official rates). Claude Sonnet 4.5 is the lower-cost option per unit — about 40% 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 Opus 5 is the better fit when you need agents and apps that call tools or functions, production chat and assistant workloads. 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 Opus 5 when
- You need agents and apps that call tools or functions.
- You need production chat and assistant workloads.
Rates on OpenLux
| Model | Provider | Rate | Discount |
|---|---|---|---|
| Claude Sonnet 4.5 | Anthropic | $0.2647 per 1M tokens | -91% |
| Claude Opus 5 | Anthropic | $0.4412 per 1M tokens | -91% |
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 Opus 5 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-opus-5"]:
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 Opus 5 questions
How much do Claude Sonnet 4.5 and Claude Opus 5 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 Opus 5 is metered at $0.4412 per 1M tokens, a -91% 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 Opus 5 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-opus-5 — request and response shapes stay identical.
Which is cheaper, Claude Sonnet 4.5 or Claude Opus 5?
Claude Sonnet 4.5 costs less per unit: $0.2647 per 1M tokens versus $0.4412 per 1M tokens, about 40% 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 Opus 5?
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 Opus 5 is the better fit when you need agents and apps that call tools or functions, production chat and assistant workloads. Both are called with the same OpenLux key, so switching between them is a one-field change to the model name.
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Route every request to the right model
OpenLux keeps Claude Sonnet 4.5, Claude Opus 5 and every other model behind one key, one endpoint and one bill. Start with free trial credit and switch models without touching your code.