Claude Sonnet 5.5 vs Kimi K2.7 Code
Pricing, context window and real answers (September 2026)
Claude Sonnet 5.5 (Anthropic) and Kimi K2.7 Code (Moonshot), compared as you can actually call them on FastMetal. Both are served from the same OpenAI-compatible endpoint and API key; switching is a change to the model string.
Specs and pricing
 Claude Sonnet 5.5 |  Kimi K2.7 Code | |
|---|---|---|
| Provider | Anthropic | Moonshot |
| Input (per 1M tokens) | ¥357.4 | ¥55 |
| Output (per 1M tokens) | ¥1,787 | ¥530 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥1,251 | ¥320 |
| Context window | 1,000,000 tokens | 262,144 tokens |
| Release date | 9/28/2026 | 6/12/2026 |
| Input modalities | text, image, file | text, image |
| Throughput (p50) | — | 142 tokens/s (n=16) |
| Arena · overall | Unranked | Unranked |
| Arena · Japanese | Unranked | Unranked |
| Arena · coding | Unranked | Unranked |
Prices are FastMetal's yen rates before tax.
Rankings: LMArena leaderboard dataset (lmarena-ai/leaderboard-dataset), CC BY 4.0, snapshot 2026-09-25; category names mapped and ratings rounded by FastMetal.
Which should you pick?
- On price, Kimi K2.7 Code: ¥530 per 1M output tokens, 70% less than Claude Sonnet 5.5.
- For long documents, Claude Sonnet 5.5: a 1,000,000-token context window against 262,144 for Kimi K2.7 Code.
- If in doubt, try both on the same key. Switching is a change to the model string, and each is billed at its own rate.
Frequently asked questions
- Which is cheaper, Claude Sonnet 5.5 or Kimi K2.7 Code?
- Per 1M output tokens, Claude Sonnet 5.5 is ¥1,787 and Kimi K2.7 Code is ¥530 on FastMetal (yen, before tax), so Kimi K2.7 Code is cheaper.
- How do the context windows of Claude Sonnet 5.5 and Kimi K2.7 Code compare?
- Claude Sonnet 5.5 takes 1,000,000 tokens; Kimi K2.7 Code takes 262,144.
- Can I use Claude Sonnet 5.5 and Kimi K2.7 Code with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "anthropic-claude-sonnet-5-5" or "japan-kimi-k2.7-code" as the model. Each is billed at its own rate from the same prepaid balance.
Try both on one API key
Create an account and add credit to call Claude Sonnet 5.5 and Kimi K2.7 Code from the browser chat and the API. No monthly fee.