Home / Compare / Claude Opus 5.5 vs GPT OSS 20B Claude Opus 5.5 vs GPT OSS 20B Claude Opus 5.5 grades higher overall (99.5 against 36.3). GPT OSS 20B costs 99% less for the same work.
Model AClaude Fable 5 Claude Haiku 4.5 Claude Opus 4.7 Claude Opus 4.8 Claude Opus 5 Claude Opus 5.5 Claude Sonnet 4.6 Claude Sonnet 5 Claude Sonnet 5.5 DeepSeek R1 0528 DeepSeek V3 DeepSeek V3.1 DeepSeek V3.2 DeepSeek V4 Flash DeepSeek V4 Flash 0731 DeepSeek V4 Pro 0813 DeepSeek V4.1 Flash Gemini 2.5 Flash Gemini 2.5 Pro Gemini 3.1 Flash Lite Gemini 3.1 Pro Gemini 3.5 Flash Gemini 3.7 Flash Gemma 3 12B IT Gemma 3 27B IT Gemma 3 4B IT Gemma 4 26B A4B IT Gemma 4 31B IT GLM 4.6 GLM 4.7 GLM 5.2 GLM 5.3 GLM 5.3 Flash GPT OSS 120B GPT OSS 20B Granite 4.2 8B Hy4 Preview Inkling Small Kimi K2.6 Kimi K3 Ling 3.1 Flash Llama 3.3 70B Instruct Turbo Llama 4 Scout 17B 16E Instruct Meta Llama 3.1 70B Instruct Turbo Meta Llama 3.1 8B Instruct Turbo MiMo V2.6 Flash MiMo V2.6 Pro MiniMax M3 Mistral Small 24B Instruct 2501 Mistral Small 3.2 24B Instruct 2506 Muse Glimmer 30B NVIDIA Nemotron 3 Super 120B A12B NVIDIA Nemotron 3 Ultra 550B A55B NVIDIA Nemotron 3.5 Lightning Phi 4 Qwen2.5 72B Instruct Qwen3 235B A22B Instruct 2507 Qwen3 30B A3B Qwen3 32B Qwen3 Coder 480B A35B Instruct Turbo Qwen3 Next 80B A3B Instruct Qwen3 VL 235B A22B Instruct Qwen3.5 27B Qwen3.5 35B A3B Qwen3.5 397B A17B Qwen3.5 9B Qwen3.6 27B Qwen3.6 35B A3B Qwen3.7 Max Qwen3.8 27B Qwen3.8 Flash Qwen3.8 Max Seed 2.0 Pro Step 5 Preview 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 Model BClaude Fable 5 Claude Haiku 4.5 Claude Opus 4.7 Claude Opus 4.8 Claude Opus 5 Claude Opus 5.5 Claude Sonnet 4.6 Claude Sonnet 5 Claude Sonnet 5.5 DeepSeek R1 0528 DeepSeek V3 DeepSeek V3.1 DeepSeek V3.2 DeepSeek V4 Flash DeepSeek V4 Flash 0731 DeepSeek V4 Pro 0813 DeepSeek V4.1 Flash Gemini 2.5 Flash Gemini 2.5 Pro Gemini 3.1 Flash Lite Gemini 3.1 Pro Gemini 3.5 Flash Gemini 3.7 Flash Gemma 3 12B IT Gemma 3 27B IT Gemma 3 4B IT Gemma 4 26B A4B IT Gemma 4 31B IT GLM 4.6 GLM 4.7 GLM 5.2 GLM 5.3 GLM 5.3 Flash GPT OSS 120B GPT OSS 20B Granite 4.2 8B Hy4 Preview Inkling Small Kimi K2.6 Kimi K3 Ling 3.1 Flash Llama 3.3 70B Instruct Turbo Llama 4 Scout 17B 16E Instruct Meta Llama 3.1 70B Instruct Turbo Meta Llama 3.1 8B Instruct Turbo MiMo V2.6 Flash MiMo V2.6 Pro MiniMax M3 Mistral Small 24B Instruct 2501 Mistral Small 3.2 24B Instruct 2506 Muse Glimmer 30B NVIDIA Nemotron 3 Super 120B A12B NVIDIA Nemotron 3 Ultra 550B A55B NVIDIA Nemotron 3.5 Lightning Phi 4 Qwen2.5 72B Instruct Qwen3 235B A22B Instruct 2507 Qwen3 30B A3B Qwen3 32B Qwen3 Coder 480B A35B Instruct Turbo Qwen3 Next 80B A3B Instruct Qwen3 VL 235B A22B Instruct Qwen3.5 27B Qwen3.5 35B A3B Qwen3.5 397B A17B Qwen3.5 9B Qwen3.6 27B Qwen3.6 35B A3B Qwen3.7 Max Qwen3.8 27B Qwen3.8 Flash Qwen3.8 Max Seed 2.0 Pro Step 5 Preview GPT OSS 20B
by OpenAI · #58 of 67 overall
Coming soon · price at launch
Context 128K
Input / 1M $0.030
Output / 1M $0.14 Better overall
Claude Opus 5.5
Grade 99.5 vs 36.3
Cheaper
GPT OSS 20B
99% less, $0.058 vs $8.00 blended
Larger context
Claude Opus 5.5
1M vs 128K tokens
Head to head Public benchmarks. Longer is better; each value links to its source.
LMArena Text Elo-style rating · LMArena (CC BY 4.0) · Oct 28, 2026 GPT OSS 20B GPT OSS 20B: —
Claude Opus 5.5 Claude Opus 5.5: —
SWE-Bench Pro % of tasks resolved · Scale AI SWE-Bench Pro · Sep 22, 2026 · reference GPT OSS 20B GPT OSS 20B: —
GPT OSS 20B GPT OSS 20B: —
Claude Opus 5.5 $1,600 /month
GPT OSS 20B $11.60 /month
GPT OSS 20B saves you $1,588 a month at this usage, $19,061 a year.
At a glance Attribute Claude Opus 5.5 GPT OSS 20B Made by Anthropic OpenAI Availability Coming soon Coming soon Overall grade Excellent · 99.5 Good · 36.3 Overall rank #1 of 67 #58 of 67 Input price $4.00 per 1M $0.030 per 1M Output price $20.00 per 1M $0.14 per 1M Context window 1,000,000 tokens 131,072 tokens Reasoning levels Yes Yes Reads images Yes No Model ID claude-opus-5-5 gpt-oss-20b
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": "gpt-oss-20b", "messages": [...]}' Questions Is Claude Opus 5.5 or GPT OSS 20B better? Claude Opus 5.5 grades 99.5 against 36.3 for GPT OSS 20B, from public benchmarks.
Which is cheaper, Claude Opus 5.5 or GPT OSS 20B? GPT OSS 20B: $0.030 in and $0.14 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.
Scores: LMArena (CC BY 4.0), 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.
