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Claude Opus 5.5 vs Qwen3.8 Flash

Claude Opus 5.5 has the stronger public benchmark scores. Qwen3.8 Flash costs 98% less for the same work, and both read a 1M-token context.

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

Qwen3.8 Flash

by Qwen

Coming soon · price at launch
Context
1M
Input / 1M
$0.11
Output / 1M
$0.38

Better overall

Claude Opus 5.5

Grade 99.5 vs —

Cheaper

Qwen3.8 Flash

98% less, $0.18 vs $8.00 blended

Larger context

Same

1M vs 1M tokens

SWE-Bench Pro

Claude Opus 5.5

89.9% vs 62.5%

Head to head

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

LMArena TextElo-style rating · LMArena (CC BY 4.0) · Oct 13, 2026
Claude Opus 5.5Claude Opus 5.5: 1,508
Qwen3.8 FlashQwen3.8 Flash: —
LMArena WebDevElo-style rating · LMArena (CC BY 4.0) · Oct 13, 2026
Claude Opus 5.5Claude Opus 5.5: 1,811
Qwen3.8 FlashQwen3.8 Flash: —
LMArena CodingElo-style rating · LMArena (CC BY 4.0) · Oct 13, 2026
Claude Opus 5.5Claude Opus 5.5: 1,545
Qwen3.8 FlashQwen3.8 Flash: —
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
Qwen3.8 FlashQwen3.8 Flash: —

Claude Opus 5.5Qwen3.8 Flashv = 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
Qwen3.8 Flash$37.88 /month

Qwen3.8 Flash saves you $1,562 a month at this usage, $18,745 a year.

At a glance

AttributeClaude Opus 5.5Qwen3.8 Flash
Made byAnthropicQwen
AvailabilityComing soonComing soon
Overall gradeExcellent · 99.5Not rated
Overall rank#1 of 67Not ranked
Input price$4.00 per 1M$0.11 per 1M
Output price$20.00 per 1M$0.38 per 1M
Context window1,000,000 tokens1,000,000 tokens
Reasoning levelsYesYes
Reads imagesYesNo
Model IDclaude-opus-5-5qwen3.8-flash

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": "qwen3.8-flash", "messages": [...]}'

Questions

Is Claude Opus 5.5 or Qwen3.8 Flash better?

One of them doesn’t have enough public benchmark scores to be graded yet; compare the benchmarks both have above.

Which is cheaper, Claude Opus 5.5 or Qwen3.8 Flash?

Qwen3.8 Flash: $0.11 in and $0.38 out per million tokens, against $4.00 and $20.00 through FullsendAI.

Which has the larger context window?

Neither: both take 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), Scale AI SWE-Bench Pro, Terminal-Bench, and model makers’ published results where marked v. Prices are FullsendAI’s, per million tokens. Data as of Oct 28, 2026.