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Claude Opus 5.5 vs Kimi K2.6

Claude Opus 5.5 grades higher overall (99.5 against 75.6). Kimi K2.6 costs 82% less for the same work.

Claude Opus 5.5

by Anthropic · #1 of 67 overall

Coming soon · price at launch
Context
1M
Input / 1M
$4.00
Output / 1M
$20.00

Kimi K2.6

by Moonshot AI · #23 of 67 overall

Coming soon · price at launch
Context
256K
Input / 1M
$0.75
Output / 1M
$3.50

Better overall

Claude Opus 5.5

Grade 99.5 vs 75.6

Cheaper

Kimi K2.6

82% less, $1.44 vs $8.00 blended

Larger context

Claude Opus 5.5

1M vs 256K tokens

SWE-Bench Pro

Claude Opus 5.5

89.9% vs 58.6%

Head to head

Public benchmarks. Longer is better; each value links to its source.

LMArena TextElo-style rating · LMArena (CC BY 4.0) · Oct 15, 2026
LMArena WebDevElo-style rating · LMArena (CC BY 4.0) · Oct 13, 2026
LMArena CodingElo-style rating · LMArena (CC BY 4.0) · Oct 15, 2026
SWE-bench Verified% of issues resolved · SWE-bench · Apr 14, 2026 · reference
Claude Opus 5.5Claude Opus 5.5: —
SWE-Bench Pro% of tasks resolved · Scale AI SWE-Bench Pro · Sep 22, 2026 · reference
Terminal-Bench 4.0% of tasks passed · Terminal-Bench · Sep 22, 2026 · reference
Kimi K2.6Kimi K2.6: —
Terminal-Bench 2.0% of tasks passed · Terminal-Bench · Apr 14, 2026 · reference
Claude Opus 5.5Claude Opus 5.5: —
LiveCodeBenchpass@1, % · LiveCodeBench · Apr 14, 2026 · reference
Claude Opus 5.5Claude Opus 5.5: —

Claude Opus 5.5Kimi K2.6v = reported by the model’s maker. — = no public score yet. Arena bars span the range across every model we grade.

What it costs you

Drag to match your monthly usage.

Claude Opus 5.5$1,600 /month
Kimi K2.6$290 /month

Kimi K2.6 saves you $1,310 a month at this usage, $15,720 a year.

At a glance

AttributeClaude Opus 5.5Kimi K2.6
Made byAnthropicMoonshot AI
AvailabilityComing soonComing soon
Overall gradeExcellent · 99.5Excellent · 75.6
Overall rank#1 of 67#23 of 67
Input price$4.00 per 1M$0.75 per 1M
Output price$20.00 per 1M$3.50 per 1M
Context window1,000,000 tokens262,144 tokens
Reasoning levelsYesNo
Reads imagesYesYes
Model IDclaude-opus-5-5kimi-k2.6

Try both with one key

Same endpoint, same key, both hosted in the USA. Change one word to switch models, in Claude Code, Cursor, Cline or your own code.

Get your API key
# Ask either model the same thing
curl https://fullsendai.com/v1/chat/completions \
  -H "Authorization: Bearer $FULLSEND_API_KEY" \
  -d '{"model": "claude-opus-5-5", "messages": [...]}'

# …then swap one word
  -d '{"model": "kimi-k2.6", "messages": [...]}'

Questions

Is Claude Opus 5.5 or Kimi K2.6 better?

Claude Opus 5.5 grades 99.5 against 75.6 for Kimi K2.6, from public benchmarks.

Which is cheaper, Claude Opus 5.5 or Kimi K2.6?

Kimi K2.6: $0.75 in and $3.50 out per million tokens, against $4.00 and $20.00 through FullsendAI.

Which has the larger context window?

Claude Opus 5.5, with 1,000,000 tokens.

Can I use both with one API key?

Yes, once they launch: both are coming soon, at the prices shown, and both will use the same FullsendAI key.

Model rankingsAll benchmarksCompare other models

Scores: LMArena (CC BY 4.0), SWE-bench, Scale AI SWE-Bench Pro, Terminal-Bench, LiveCodeBench, and model makers’ published results where marked v. Prices are FullsendAI’s, per million tokens. Data as of Oct 28, 2026.