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Claude Fable 5 vs GPT OSS 120B

Claude Fable 5 grades higher overall (90.7 against 46.1). GPT OSS 120B costs 100% less for the same work.

Claude Fable 5

by Anthropic · #3 of 67 overall

Coming soon · price at launch
Context
1M
Input / 1M
$10.00
Output / 1M
$50.00

GPT OSS 120B

by OpenAI · #53 of 67 overall

Coming soon · price at launch
Context
128K
Input / 1M
$0.037
Output / 1M
$0.17

Better overall

Claude Fable 5

Grade 90.7 vs 46.1

Cheaper

GPT OSS 120B

100% less, $0.070 vs $20.00 blended

Larger context

Claude Fable 5

1M vs 128K tokens

SWE-bench Verified

Claude Fable 5

95% vs 62.4%

Head to head

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

LMArena TextElo-style rating · LMArena (CC BY 4.0) · Oct 28, 2026
LMArena WebDevElo-style rating · LMArena (CC BY 4.0) · Oct 13, 2026
Claude Fable 5Claude Fable 5: 1,624
GPT OSS 120BGPT OSS 120B: —
LMArena CodingElo-style rating · LMArena (CC BY 4.0) · Oct 28, 2026
Aider Polyglot% of exercises solved · Aider (aider.chat) · Aug 6, 2025
Claude Fable 5Claude Fable 5: —
SWE-bench Verified% of issues resolved · SWE-bench · Jun 9, 2026 · reference
SWE-Bench Pro% of tasks resolved · Scale AI SWE-Bench Pro · Jun 9, 2026 · reference
Claude Fable 5Claude Fable 5: 80%v
GPT OSS 120BGPT OSS 120B: —
Terminal-Bench 2.1% of tasks passed · Terminal-Bench · Jun 9, 2026 · reference
GPT OSS 120BGPT OSS 120B: —

Claude Fable 5GPT OSS 120Bv = 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 Fable 5$4,000 /month
GPT OSS 120B$14.20 /month

GPT OSS 120B saves you $3,986 a month at this usage, $47,830 a year.

At a glance

AttributeClaude Fable 5GPT OSS 120B
Made byAnthropicOpenAI
AvailabilityComing soonComing soon
Overall gradeExcellent · 90.7Good · 46.1
Overall rank#3 of 67#53 of 67
Input price$10.00 per 1M$0.037 per 1M
Output price$50.00 per 1M$0.17 per 1M
Context window1,000,000 tokens131,072 tokens
Reasoning levelsYesYes
Reads imagesYesNo
Model IDclaude-fable-5gpt-oss-120b

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-fable-5", "messages": [...]}'

# …then swap one word
  -d '{"model": "gpt-oss-120b", "messages": [...]}'

Questions

Is Claude Fable 5 or GPT OSS 120B better?

Claude Fable 5 grades 90.7 against 46.1 for GPT OSS 120B, from public benchmarks.

Which is cheaper, Claude Fable 5 or GPT OSS 120B?

GPT OSS 120B: $0.037 in and $0.17 out per million tokens, against $10.00 and $50.00 through FullsendAI.

Which has the larger context window?

Claude Fable 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, and model makers’ published results where marked v. Prices are FullsendAI’s, per million tokens. Data as of Oct 28, 2026.