Neither wins outright: Anthropic: Claude Sonnet 5.5 is the pick when cost matters at scale, MoonshotAI: Kimi K3 (batch) when you need seed (reproducible sampling).
| Spec | Anthropic: Claude Sonnet 5.5 | MoonshotAI: Kimi K3 (batch) |
|---|---|---|
| Provider | Anthropic | Moonshotai |
| Input price (per 1M tokens) | $2.00 | $2.28 |
| Output price (per 1M tokens) | $10.00 | $11.40 |
| Blended price (3:1 input/output) | $4.00 | $4.56 |
| Cheaper than … of all models we track | 15% | 12% |
| Context window | 1M tokens (~1,500 pages) | 1.0M tokens (~1,573 pages) |
| Larger context than … of all models | 69% | 81% |
| Max output per response | 128K tokens (~96,000 words) | 16K tokens (~12,300 words) |
| Input types | text, image, file | text, image, video |
| Output types | text | text |
| Free variant | No | No |
| Listed since | 2026-09-28 | 2026-07-16 |
Monthly cost at list price for five common workloads. Token counts per unit are stated so you can scale them to your own traffic. A workload that does not fit a model's context window is marked rather than priced.
| Workload (per month) | Anthropic: Claude Sonnet 5.5 | MoonshotAI: Kimi K3 (batch) | Difference |
|---|---|---|---|
| Customer-support chatbot 50,000 conversations — each a 6-turn conversation (1,500 in / 400 out tokens) | $350 | $399 | Anthropic: Claude Sonnet 5.5 saves $49.00 |
| RAG search over documents 20,000 questions — each a question answered from ~8 retrieved passages (6,000 in / 500 out tokens) | $340 | $388 | Anthropic: Claude Sonnet 5.5 saves $47.60 |
| Coding / tool-using agent 2,000 tasks — each a multi-step task with tool calls and file context (60,000 in / 6,000 out tokens) | $360 | $410 | Anthropic: Claude Sonnet 5.5 saves $50.40 |
| Batch summarisation 10,000 documents — each a 6,000-word report summarised to a page (8,000 in / 600 out tokens) | $220 | $251 | Anthropic: Claude Sonnet 5.5 saves $30.80 |
| Long-document analysis 500 documents — each a 150-page contract or codebase read in one pass (100,000 in / 2,000 out tokens) | $110 | $125 | Anthropic: Claude Sonnet 5.5 saves $15.40 |
| Capability | Anthropic: Claude Sonnet 5.5 | MoonshotAI: Kimi K3 (batch) | What it lets you do |
|---|---|---|---|
| Tool / function calling | ✓ Yes | ✓ Yes | call your APIs and run agent loops |
| Structured output (JSON schema) | ✓ Yes | ✓ Yes | return JSON that validates against your schema |
| Reasoning / thinking mode | ✓ Yes | ✓ Yes | spend extra tokens thinking before answering hard problems |
| Image input | ✓ Yes | ✓ Yes | read screenshots, charts and scanned pages |
| Audio input | — | — | take speech or audio directly |
| File / PDF input | ✓ Yes | — | accept documents without your own parsing step |
| Image output | — | — | generate images, not just text |
| Built-in web search | ✓ Yes | — | answer from live web results |
| Seed (reproducible sampling) | — | ✓ Yes | repeat a generation for tests and evals |
| Log-probabilities | — | — | read token confidence for classification and scoring |
From each model's published parameters and input/output types. “—” means not advertised, not proven absent.
| Date | Model | Input / 1M | Output / 1M |
|---|---|---|---|
| 2026-09-23 | MoonshotAI: Kimi K3 (batch) | $2.28 | $11.40 |
Neither wins outright: Anthropic: Claude Sonnet 5.5 is the pick when cost matters at scale, MoonshotAI: Kimi K3 (batch) when you need seed (reproducible sampling). In short: Anthropic: Claude Sonnet 5.5 when cost matters at scale, you need file / PDF input, you need built-in web search, you generate long outputs in one go; MoonshotAI: Kimi K3 (batch) when you need seed (reproducible sampling).
Anthropic: Claude Sonnet 5.5 is cheaper: $4.00 vs $4.56 per 1M tokens at a typical 3:1 input/output mix, 12% less. For 50,000 support conversations a month that is $350 against $399.
Anthropic: Claude Sonnet 5.5 costs $2.00 per 1M input tokens and $10.00 per 1M output tokens; MoonshotAI: Kimi K3 (batch) costs $2.28 input and $11.40 output. Output tokens are billed separately, so long answers shift the gap.
MoonshotAI: Kimi K3 (batch): 1.0M tokens, about 1,573 pages, against 1M (about 1,500 pages) for Anthropic: Claude Sonnet 5.5.
Tool calling — Anthropic: Claude Sonnet 5.5: yes, MoonshotAI: Kimi K3 (batch): yes. JSON-schema structured output — Anthropic: Claude Sonnet 5.5: yes, MoonshotAI: Kimi K3 (batch): yes.
Yes, both accept image input.
No free variant is listed for either; both are pay-per-token.
Anthropic: Claude Sonnet 5.5 can write up to 128K tokens (about 96,000 words) per response; MoonshotAI: Kimi K3 (batch) up to 16K (about 12,300 words).
Anthropic: Claude Sonnet 5.5 was listed on 2026-09-28; MoonshotAI: Kimi K3 (batch) on 2026-07-16.
Anthropic: Claude Sonnet 5.5: price unchanged since we started tracking it on 2026-09-29. MoonshotAI: Kimi K3 (batch): input price cut 24% ($3.00 → $2.28/1M), output price cut 24% ($15.00 → $11.40/1M) on 2026-09-23.
Claude Sonnet 5.5 is Anthropic's Sonnet-class model for well-scoped everyday work, succeeding Claude Sonnet 5 as a direct upgrade. It is especially strong at building features, fixing bugs, and producing...
Full Anthropic: Claude Sonnet 5.5 specs →Kimi K3 is a 2.8T parameter open-weight multimodal reasoning model from Moonshot AI. It is suited for complex coding, knowledge work, and long-horizon agentic workflows, and is particularly strong at...
Full MoonshotAI: Kimi K3 (batch) specs →