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Claude Opus 5.5 vs DeepSeek V3

Claude Opus 5.5 grades higher overall (99.5 against 47.5). DeepSeek V3 costs 94% 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

DeepSeek V3

by DeepSeek · #51 of 67 overall

Coming soon · price at launch
Context
160K
Input / 1M
$0.32
Output / 1M
$0.89

Better overall

Claude Opus 5.5

Grade 99.5 vs 47.5

Cheaper

DeepSeek V3

94% less, $0.46 vs $8.00 blended

Larger context

Claude Opus 5.5

1M vs 160K tokens

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
Claude Opus 5.5Claude Opus 5.5: 1,811
DeepSeek V3DeepSeek V3: —
LMArena CodingElo-style rating · LMArena (CC BY 4.0) · Oct 15, 2026
Aider Polyglot% of exercises solved · Aider (aider.chat) · Dec 25, 2024
Claude Opus 5.5Claude Opus 5.5: —
SWE-bench Verified% of issues resolved · SWE-bench · Dec 25, 2024 · reference
Claude Opus 5.5Claude Opus 5.5: —
SWE-Bench Pro% of tasks resolved · Scale AI SWE-Bench Pro · Sep 22, 2026 · reference
DeepSeek V3DeepSeek V3: —
Terminal-Bench 4.0% of tasks passed · Terminal-Bench · Sep 22, 2026 · reference
DeepSeek V3DeepSeek V3: —
LiveCodeBenchpass@1, % · LiveCodeBench · Dec 25, 2024 · reference
Claude Opus 5.5Claude Opus 5.5: —

Claude Opus 5.5DeepSeek V3v = 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
DeepSeek V3$99.60 /month

DeepSeek V3 saves you $1,500 a month at this usage, $18,005 a year.

At a glance

AttributeClaude Opus 5.5DeepSeek V3
Made byAnthropicDeepSeek
AvailabilityComing soonComing soon
Overall gradeExcellent · 99.5Good · 47.5
Overall rank#1 of 67#51 of 67
Input price$4.00 per 1M$0.32 per 1M
Output price$20.00 per 1M$0.89 per 1M
Context window1,000,000 tokens163,840 tokens
Reasoning levelsYesNo
Reads imagesYesNo
Model IDclaude-opus-5-5deepseek-v3

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": "deepseek-v3", "messages": [...]}'

Questions

Is Claude Opus 5.5 or DeepSeek V3 better?

Claude Opus 5.5 grades 99.5 against 47.5 for DeepSeek V3, from public benchmarks.

Which is cheaper, Claude Opus 5.5 or DeepSeek V3?

DeepSeek V3: $0.32 in and $0.89 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), Aider (aider.chat), 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.