Claude Sonnet 4.5 — API Pricing & Benchmarks
Claude Sonnet 4.5 is Anthropic's previous-generation reasoning model, released in 2025-09. The API costs $3.00 per 1M input tokens and $15.0 per 1M output tokens ($6.00 blended at a 3:1 ratio), with cached input at $0.30. It supports a 200K-token context window.
Explore provider routes and additional benchmark sources for Claude Sonnet 4.5
| Provider | Anthropic |
| Input price / 1M tokens | $3.00 |
| Output price / 1M tokens | $15.0 |
| Cached input / 1M tokens | $0.30 |
| Blended price (3:1) | $6.00 |
| Context window | 200K |
| Max output tokens | 64K |
| Knowledge cutoff | — |
| License | proprietary |
| Input modalities | T+I |
| Output speed (tok/s) | — |
| Released | 2025-09 |
| LMArena Elo | 1438 |
Where Claude Sonnet 4.5 fits
On a blended 3:1 basis Claude Sonnet 4.5 costs $6.00 per 1M tokens, cheaper than 15% of the 80 priced models in this index. It is a previous-generation model: usually only worth choosing if you have an existing integration, negotiated pricing, or need its specific behavior, since newer siblings offer better price-performance. Cached input is priced at $0.30 (90% below standard input), which rewards prompt structures with long stable prefixes — see our caching guide.
Price history
| Period | Input $/1M | Output $/1M | Cached $/1M |
|---|---|---|---|
| 2026-08-25 → current | $3.00 | $15.0 | $0.30 |
No list-price changes recorded since tracking began. Full dataset: price-history.json (CC BY 4.0).
Alternatives at a similar price
- Claude Sonnet 4.6 (Anthropic) — $6.00/1M blended, AA Index 48.4
- Kimi K3 (Moonshot AI) — $6.00/1M blended, AA Index 59.7
- GPT-5.4 (OpenAI) — $5.63/1M blended, AA Index 53.1
- GPT-5.3 Codex (OpenAI) — $4.81/1M blended, AA Index 45.5
About Anthropic
Anthropic builds the Claude family, organized into Opus (flagship), Sonnet (mid-tier) and Haiku (small) tiers alongside the Fable line. Claude models currently lead the Artificial Analysis Intelligence Index and are particularly strong on agentic-coding benchmarks such as SWE-bench Verified.