Claude Opus 4.6 vs Kimi K2.5
AnthropicMoonshot AIboth via one key, provider price + 3%
Claude Opus 4.6 and Kimi K2.5 both launched within weeks of each other (Feb 4, 2026 and Jan 27, 2026) and both target agentic coding work, but they sit at opposite ends of the price spectrum. Opus 4.6 leads nearly every Design Arena coding category by a wide margin; Kimi K2.5 trades some of that ranking for a context window and a price that make it viable for large-scale or long-running agent pipelines. Both are available on OpenKey with one key and a flat 3% fee over provider list price.
Spec vs spec
| Spec | Claude Opus 4.6 | Kimi K2.5 |
|---|---|---|
| Context window | 1M | 262K |
| Max output | 128K | — |
| Input modalities | text, image, file | text, image |
| Output modalities | text | text |
| Released | Feb 4, 2026 | Jan 27, 2026 |
| Reasoning | optional | optional |
Pricing
Per 1M tokens. Provider price plus the flat 3% fee — the sum is what you pay.
anthropic/claude-opus-4.6
Input · 1M tokens
$5.00 + 3%$5.15
Output · 1M tokens
$25.00 + 3%$25.75
Cache read · 1M tokens
$0.500 + 3%$0.515
Cache write · 1M tokens
$6.25 + 3%$6.44
FEE — FLAT, EVERY MODEL3%
moonshotai/kimi-k2.5
Input · 1M tokens
$0.375 + 3%$0.386
Output · 1M tokens
$2.02 + 3%$2.09
FEE — FLAT, EVERY MODEL3%
One workload, priced on both
10M input + 2M output tokens at each model's price, flat 3% fee included.
anthropic/claude-opus-4.6
$103.00
$100.00 provider + 3%
moonshotai/kimi-k2.5Cheaper
$8.03
$7.80 provider + 3%
Benchmarks
Design Arena categories where both models have results. Higher Elo and lower rank win.
| Claude Opus 4.6 | Kimi K2.5 | |||
|---|---|---|---|---|
| Category | Elo | Rank | Elo | Rank |
| 3D | 1351 | #4 | 1286 | #22 |
| androidnative | 1216 | #11 | 1132 | #17 |
| ASCII art | 1307 | #6 | 1214 | #17 |
| Code | 1342 | #3 | 1286 | #20 |
| Data viz | 1322 | #5 | 1270 | #21 |
| Full-stack | 1288 | #4 | 1182 | #14 |
| Game dev | 1344 | #4 | 1272 | #23 |
| Mobile apps | 1261 | #3 | 1186 | #20 |
| SVG | 1288 | #4 | 1210 | #25 |
| UI components | 1350 | #3 | 1290 | #19 |
| Web apps | 1266 | #4 | 1194 | #15 |
| Websites | 1338 | #3 | 1291 | #16 |
Head-to-head preference voting. How we filter and rank
Pricing math on a real workload
Opus 4.6 provider pricing is $5.00/M input and $25.00/M output; on OpenKey that's $5.00 x 1.03 = $5.15/M input and $25.00 x 1.03 = $25.75/M output. Kimi K2.5 provider pricing is $0.375/M input and $2.025/M output, landing at $0.375 x 1.03 = $0.38625/M input and $2.025 x 1.03 = $2.08575/M output on OpenKey.
Run the same job — 10M input tokens, 2M output tokens — and Opus 4.6 costs $100.00 while Kimi K2.5 costs $7.80. That's a 13.33x gap on input price alone. If you're calling a model thousands of times a day for agent loops, that difference compounds fast. Opus 4.6 also charges for prompt caching ($0.50/M read, $6.25/M write); Kimi K2.5 doesn't expose cache pricing in this catalog.
Coding and agent benchmarks
On Design Arena's agents arena, Opus 4.6 ranks #4 in fullstack (elo 1288, 68.6% win rate), #3 in mobileapps (elo 1261, 60.5%), #4 in webapps (elo 1266, 60.9%), and #11 in androidnative (elo 1216, 68.8% win rate). Kimi K2.5 ranks #14 in fullstack (elo 1182, 54.2%), #20 in mobileapps (elo 1186, 49.3%), #15 in webapps (elo 1194, 50.3%), and #17 in androidnative (elo 1132, 57.8%). Kimi K2.5's one standout is godotgamedev, where it ranks #2 (elo 1254, 59.5% win rate) — a category Opus 4.6 doesn't appear in.
In the models arena (single-shot code/design tasks), Opus 4.6 takes #3 in codecategories (elo 1342, 63.9%) and #3 in uicomponent (elo 1350, 64.5%); Kimi K2.5 lands at #20 (elo 1286, 54.7%) and #19 (elo 1290, 54.2%) respectively. Opus 4.6 is ahead across every directly comparable category.
Context and long-document work
Opus 4.6 supports a 1,000,000-token context window with up to 128,000 max completion tokens. Kimi K2.5 supports 262,144 tokens context with no stated max completion cap in this catalog. That's a 3.81x context advantage for Opus 4.6 — relevant if you're feeding entire codebases, long transcripts, or multi-document RAG contexts in a single call. For most agent turns and file-level tasks, 262K tokens is still plenty; the gap matters mainly for repo-scale or book-length inputs.
Modality and tooling differences
Opus 4.6 accepts text, image, and file inputs and outputs text — the file input support matters for document-heavy agent workflows. Kimi K2.5 accepts text and image only. Opus 4.6 also exposes `verbosity` and `top_k` as tunable parameters alongside the standard set; Kimi K2.5 adds `logit_bias`, `logprobs`, `top_logprobs`, `seed`, and `min_p`, giving it finer sampling control for teams doing custom decoding strategies. Both support tool calling, structured outputs, and reasoning effort toggles, though Opus 4.6 exposes four reasoning effort levels (max/high/medium/low) while Kimi K2.5's reasoning is on by default with no effort tiers listed.
Which model for which job
| Use case | Pick | Why |
|---|---|---|
| Production coding agent with quality bar | Claude Opus 4.6 | Ranks #3-#4 across fullstack, codecategories, and uicomponent on Design Arena |
| High-volume agent swarm or batch jobs | Kimi K2.5 | $7.80 vs $100.00 for the same 10M-in/2M-out workload |
| Repo-scale or book-length document input | Claude Opus 4.6 | 1M token context vs 262,144 — a 3.81x gap |
| Godot/game-dev agent tasks | Kimi K2.5 | Ranks #2 in godotgamedev, a category Opus 4.6 has no entry in |
| Document-heavy workflows with file uploads | Claude Opus 4.6 | Supports file input modality; Kimi K2.5 only accepts text and image |
| Budget-constrained prototyping | Kimi K2.5 | Input price is $0.38625/M on OpenKey vs $5.15/M for Opus 4.6 |
Questions
- How much more expensive is Claude Opus 4.6 than Kimi K2.5?
- Input tokens cost 13.33x more on Opus 4.6 ($5.15/M vs $0.38625/M on OpenKey, both including the 3% fee). On a 10M-input/2M-output workload, that's $100.00 for Opus 4.6 versus $7.80 for Kimi K2.5.
- Which model has the bigger context window?
- Claude Opus 4.6 supports 1,000,000 tokens of context, 3.81x larger than Kimi K2.5's 262,144 tokens. Opus 4.6 also allows up to 128,000 tokens of output; Kimi K2.5 has no stated max completion cap.
- Is Kimi K2.5 competitive on coding benchmarks?
- Not against Opus 4.6 directly — Kimi K2.5 ranks #14-#20 in fullstack, mobileapps, and webapps on Design Arena's agents arena, while Opus 4.6 ranks #3-#4 in the same categories. Kimi K2.5's one win is godotgamedev at #2.
- Can I use both models through one API key?
- Yes. Both Claude Opus 4.6 and Kimi K2.5 are available on OpenKey with a single key and a flat 3% fee added to each provider's list price — no separate accounts or billing setup needed.