Claude Opus 5 vs Kimi K3
Claude Opus 5 wins on Overall, Coding, Multimodal. Every numeric field is compared below, with a worked monthly-cost example and a pick rule for each use case.
Verdict at a glance
Choose Claude Opus 5 if you…
- Dependable and stable
- Strong reasoning depth
- Strong long-document handling
- Best for: Deep reasoning, Long documents, Coding
Choose Kimi K3 if you…
- Best-in-class long text
- Open-source and self-hostable
- Strong codebase understanding
- Fair price
- Best for: Long-document reading, Codebase analysis, Chinese
Head-to-head aggregate scores
Scores are 0–100, aggregated from public benchmark information and independently weighted across three leaderboards. Rank is out of 22 tracked models.
Aggregated from public sources and independently weighted; methodology on the Terms page. Scores within 3 points are treated as statistically tied.
Specs & pricing — every field side by side
List API prices in USD per 1M tokens. The highlighted cell is the stronger value/capability on that row.
| Dimension | Claude Opus 5 | Kimi K3 | Verdict |
|---|---|---|---|
| Vendor | Anthropic (US) | Moonshot AI (CN) | Different vendors |
| Released | 2026.07 | 2026.06 | Claude Opus 5 is newer |
| Overall (rank) | 87 · #2 | 77 · #8 | Claude Opus 5 +10 |
| Coding | 97 · #2 | 71 · #11 | Claude Opus 5 +26 |
| Multimodal | 91 · #5 | 81 · #10 | Claude Opus 5 +10 |
| Context window | 1M | 256K | Claude Opus 5 larger |
| Max output | 128K | 64K | Kimi K3 longer |
| Effective-context | 97 | 99 | Kimi K3 more reliable |
| Input $/1M | $5 | $3 | Kimi K3 cheaper |
| Output $/1M | $25 | $15 | Kimi K3 cheaper |
| Cache discount | 90% off | custom | Claude Opus 5 deeper |
| Speed | ~45 tok/s | ~45 tok/s | Tie |
| TTFT | 0.9s | 0.7s | Kimi K3 snappier |
| Function calling | 90 | 80 | Claude Opus 5 ahead |
| Refusal rate | ~7% | ~6% | Kimi K3 less restrictive |
| English | 96 | 75 | Claude Opus 5 |
| Chinese | 80 | 92 | Kimi K3 |
| Modalities | text, image | text, image | Same |
| Open weights | No | Yes | Kimi K3 is open |
| Fine-tuning | No | No | |
| Free tier | No free tier | Kimi App free; free quota on the open platform | |
| SOC2 / no-train | yes / yes | no / yes | |
| Private deployment | No | Yes | Kimi K3 |
Fields drawn from vendor public documentation and the Modelspectra 22-model dataset; speed varies with network, concurrency and prompt length. Verify current pricing before purchase.
Dimension-by-dimension analysis
Reasoning & overall intelligence
Claude Opus 5 leads the overall aggregate by 10 points (87 vs 77). That is a meaningful, not marginal, edge on hard, multi-step reasoning, while Kimi K3 remains a strong generalist that is not out of its depth on routine work.
Agentic coding
This is a decisive gap: Claude Opus 5 scores 97 against 71. On multi-file edits, SWE-style tickets and long-horizon agent loops Claude Opus 5 needs fewer correction turns; Kimi K3 is still competent for scripts and assisted completion but trails as task complexity rises.
Multimodal
Claude Opus 5 leads multimodal 91 vs 81. Neither emits native video, so the comparison is about parsing images and documents, not generation.
Speed & latency
Claude Opus 5 is faster in interactive use: ~45 tok/s with 0.9s TTFT versus ~45 tok/s with 0.7s TTFT (about 1.0× the throughput). For conversational UIs where perceived responsiveness drives retention, that edge is a real product factor even when raw reasoning is lower.
Context: window vs usable recall
Nominal windows are 1M for Claude Opus 5 and 256K for Kimi K3. Crucially, the larger nominal window does not win on usable recall: Claude Opus 5 advertises 1M but Kimi K3 scores higher on effective-context (99 vs 97), i.e. it actually retains more of what it was given.
Price & total cost
Kimi K3 is the cheaper API at $3/$15 versus Claude Opus 5 at $5/$25 per 1M input/output tokens — list input is about 1.7× lower. Cache discounts (Claude Opus 5 90%) shift the effective bill, worked out below.
Chinese vs English
English: Claude Opus 5 96 vs Kimi K3 75. Chinese: 80 vs 92. For Chinese-language production, Kimi K3 is the stronger pick. Note that non-Chinese models generally require overseas network access for their APIs.
Tool use & ecosystem
Function-calling score: Claude Opus 5 90 vs Kimi K3 80, so Claude Opus 5 has the edge on structured tool use. Neither offers standard fine-tuning. Factor in existing SDK/plugin familiarity — switching cost often outweighs a few-point tool-use gap.
Cost worked example — same workload, real token math
Assume a production workload of 100M input + 30M output tokens per month, with 90% of input tokens served from cache. Figures use public list prices.
| Scenario · per month | Claude Opus 5 | Kimi K3 | Gap |
|---|---|---|---|
| List priceno cache applied | $1,250100M in × $5 + 30M out × $25 | $750100M in × $3 + 30M out × $15 | 1.67×gap |
| With caching90% of inputs cache-hit | $84590M cached in × $0.5 + 10M in × $5 + 30M out × $25 | $750no published cache discount | 1.13×gap |
Illustrative model; your input/output mix and cache-hit ratio change the result. Prices are list rates before any enterprise agreement.