Claude Sonnet 4.5
Claude Sonnet 4.5 is served by 3 providers that kRouter can route to, with a 200K-token context window and pricing from $3.00 per 1M input tokens. Because more than one provider offers it, the price you pay depends on which one you route to — the same request, the same model, different bills.
Where to get Claude Sonnet 4.5
| Provider | Route as |
|---|---|
| GitHub Copilot | gh/claude-sonnet-4.5 |
| Kiro AI | kr/claude-sonnet-4.5 |
| Blackbox AI | blackbox/claude-sonnet-4.5 |
What Claude Sonnet 4.5 is suited for
A 200K window comfortably holds a long file plus its surrounding context, which covers most day-to-day coding turns without compaction. It supports extended reasoning, which helps on debugging and multi-step planning but spends output tokens on thinking before the answer appears — worth knowing when you set max_tokens. Tool and function calling are supported, so it can drive an agent loop. It accepts images, so screenshots and diagrams can go straight into the prompt. Cached input is billed at $0.30 against $3.00 fresh, which is the difference that matters most for agent work — the same context is resent on every turn.
Specs
- Context window
- 200K
- Max output
- 64K
- Input / 1M
- $3.00
- Output / 1M
- $15.00
- Extended reasoning
- Image input
- Tool / function calling
Cheaper alternatives to Claude Sonnet 4.5
Comparable capabilities at a lower rate. With a kRouter combo you can send routine turns to one of these and reserve Claude Sonnet 4.5 for the work that actually needs it.
- GPT 5.4$3.00 in · $12.00 out per 1M
- GPT 5.4 Mini$3.00 in · $12.00 out per 1M
- GPT-5$3.00 in · $12.00 out per 1M
- GPT-5 Nano$3.00 in · $12.00 out per 1M
Claude Sonnet 4.5 FAQ
How much does Claude Sonnet 4.5 cost?
Claude Sonnet 4.5 is $3.00 per 1M input tokens and $15.00 per 1M output tokens. Cached input is $0.30, which matters a lot for agent work that resends the same context each turn.
Which providers serve Claude Sonnet 4.5?
3 providers: GitHub Copilot, Kiro AI, Blackbox AI. Through kRouter you can switch between them by changing the route prefix, without changing your tool.
What is Claude Sonnet 4.5's context window?
200K tokens, with up to 64K tokens of output. kRouter publishes this on /v1/models as context_length, so clients read the real number instead of guessing from the model name.
Is there a cheaper alternative to Claude Sonnet 4.5?
Yes — GPT 5.4 ($3.00/1M in), GPT 5.4 Mini ($3.00/1M in), GPT-5 ($3.00/1M in), GPT-5 Nano ($3.00/1M in) are cheaper with comparable capabilities. A kRouter combo can send routine turns to one of those and keep Claude Sonnet 4.5 for the work that needs it.
Route to Claude Sonnet 4.5 from any tool
kRouter runs locally and gives Claude Code, Cursor, Codex and the rest one endpoint that reaches every provider above — with automatic failover. Free and MIT-licensed.
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