Kimi K3 vs Claude Opus 5.5: API price, context and cost per task
Moonshot AI's open-weight Kimi K3 against Anthropic's flagship - a low-priced challenger versus the premium default for agents.
On output, Kimi K3 is 1.3x cheaper ($16 vs $20 per million tokens). On input, Kimi K3 is 21x cheaper ($0.192 vs $4 per million tokens). Kimi K3 reads more per request: 1,048,576 tokens against 1,000,000.
Data updated 2026-11-11 - source: public OpenRouter model list, refreshed daily. Prices in USD, excluding VAT.
Specs and prices side by side
| Kimi K3 | Claude Opus 5.5 | |
|---|---|---|
| Vendor | Moonshot AI | Anthropic |
| Input, per 1M tokens | $0.192 | $4 |
| Output, per 1M tokens | $16 | $20 |
| Cached input, per 1M | $0.182 | $0.2 |
| Batch (input / output) | $2.28 / $11.4 | $2 / $10 |
| Context window | 1,048,576 | 1,000,000 |
| Max output | 943,718 | 128,000 |
| Input types | text, images, video | text, images, files |
| Reasoning | Yes | Yes |
| Tool calling | Yes | Yes |
| On OpenRouter since | 16 Jul 2026 | 22 Sep 2026 |
Highlighted: the cheaper price or the larger limit. "Not published" means the figure is not in the public model listing yet.
What a month of work costs
Four typical workloads at today's list prices. Reasoning models also bill their thinking as output tokens, so treat output-heavy numbers as a floor.
| Workload | Kimi K3 | Claude Opus 5.5 | Difference |
|---|---|---|---|
| Support chatbot10,000 conversations a month, about 1,500 input and 400 output tokens each | $66.88 | $140 | Kimi K3 2.1x cheaper |
| Coding agent300 tasks a month, about 80,000 input tokens (code context re-read across steps) and 8,000 output tokens each | $43.01 | $144 | Kimi K3 3.3x cheaper |
| Coding agent with caching70% of input served from the prompt cache | $42.84 | $80.16 | |
| Long-document analysis1,000 documents a month, about 50,000 tokens in and a 1,500-token summary out | $33.60 | $230 | Kimi K3 6.8x cheaper |
| Content drafting600 articles a month, about 3,000 tokens of brief in and 2,500 tokens of draft out | $24.35 | $37.20 | Kimi K3 1.5x cheaper |
Price stability over the last 30 days
- Kimi K3: 15 price changes since 12 Oct 2026. Input ranged $0.159 - $0.8, output $10 - $20 per million tokens. Volatile: the listed price follows whichever provider OpenRouter currently routes to, so budget with the upper end of the range.
- Claude Opus 5.5: no change in the last 30 days.
Kimi K3: price log
| Date | Input | Output |
|---|---|---|
| 2026-11-05 | $0.192 | $16 |
| 2026-11-04 | $0.2 | $16 |
| 2026-10-30 | $0.192 | $15 |
| 2026-10-29 | $0.192 | $20 |
| 2026-10-28 | $0.159 | $20 |
| 2026-10-27 | $0.2 | $20 |
| 2026-10-26 | $0.18 | $16 |
| 2026-10-24 | $0.239 | $10.8 |
What the vendors and benchmarks say
Kimi K3
"Kimi K3 is a 2.8T parameter open-weight multimodal reasoning model from Moonshot AI."model card on OpenRouter
- Open weights: you can run it on your own hardware instead of paying per token. Source: Moonshot AI
- First place in Frontend Code Arena (1679 points) in summer 2026 voting. Source: arena.ai
- 50.9% on the AA-Omniscience hallucination test (lower is better). Source: Artificial Analysis
Claude Opus 5.5
"Claude Opus 5.5 is Anthropic's flagship model for demanding reasoning, coding, and long-horizon agentic work, succeeding Claude Opus 5."model card on OpenRouter
- Released on 22 September 2026 as the first model of the Claude 5.5 family. Source: Anthropic
- Anthropic says a typical task at default settings costs 40% less than on Opus 5, because the model uses fewer tokens, and that generation is over 30% faster. Source: Anthropic
- Thinking is always on and cannot be switched off; the default effort level is medium (Opus 5 defaulted to high). Source: Anthropic model documentation
- Terminal-Bench 4.0: 66.4%; GDPval-AA v2.1: 1846 Elo. In Anthropic's test, 16 of 18 reports written from incomplete sources contained no invented figure. Source: Anthropic
- Fast mode costs $8 / $40 and batch mode $2 / $10 per million tokens; knowledge cutoff June 2026. Source: Anthropic
Which one to pick
Kimi K3 is much cheaper and its weights are open; in summer 2026 it was first in Frontend Code Arena. Its weak spot is factual reliability (50.9% on the AA-Omniscience hallucination test), while Anthropic reports that Opus 5.5 kept invented figures out of 16 of 18 source-based reports. Use K3 for frontend and bulk generation, Opus 5.5 where mistakes are expensive.
Cheaper models with a similar context window
Models from our comparison set that cost less than both on a blended basis and support tool calling. They are not equivalent in quality - test before switching.
- Qwen3.8 Max (Alibaba (Qwen)): $2 / $6 per million tokens, 1M context
- Gemini 3.8 Flash (Google): $0.825 / $4.13 per million tokens, 1.05M context
- DeepSeek V4 Pro (DeepSeek): $0.955 / $1.91 per million tokens, 1.05M context
Related reading
- Kimi K3: input unchanged, output +3%. New rate: 0.30 / 11.94 dollars per million tokens
- Kimi K3: input -20%, output unchanged. New rate: 0.24 / 11.94 dollars per million tokens
- Kimi K3 API price cut: input tokens now $0.45 per million
- Claude Fable 5.2 vs Opus 5.5: Price, Benchmarks, Which to Pick
- Claude Opus 5.5 vs GPT-6 Astra: Plan or API?
- Claude Pro vs. Max vs. API: Opus 5.5 costs compared
How we calculate
Prices are the public per-token list rates from OpenRouter's model list, which match the vendors' own API prices for first-party models and show the current routed price for open-weight models served by several hosts. Monthly costs multiply those rates by the token volumes in each workload; caching assumes the stated share of input is billed at the cached-input rate. Benchmarks and claims are quoted from the named sources, mostly the vendors themselves - treat them as a guide and test on your own tasks. See also the AI cost calculator and all tracked model prices.
Frequently asked questions
Which is cheaper, Kimi K3 or Claude Opus 5.5?
As of 11 Nov 2026, Kimi K3 costs $0.192 per million input tokens and $16 per million output tokens; Claude Opus 5.5 costs $4 and $20. Kimi K3 is cheaper in 4 of the 4 monthly workloads we price on this page. The real bill also depends on how many reasoning tokens each model writes.
Which has the larger context window?
Kimi K3 reads up to 1,048,576 tokens and can write up to 943,718; Claude Opus 5.5 reads up to 1,000,000 and writes up to 128,000.
How much does a support chatbot cost on each model?
For 10,000 conversations a month (about 15 million input and 4 million output tokens) you would pay about $66.88 on Kimi K3 and $140 on Claude Opus 5.5 at list prices, before any caching or batch discounts.
Do they offer prompt caching or batch discounts?
Kimi K3 lists cached input at $0.182 per million and a batch rate of $2.28 / $11.4. Claude Opus 5.5 lists cached input at $0.2 per million and a batch rate of $2 / $10. Caching matters most for agents and chatbots that resend the same context on every turn.
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