Compare · ModelsLive · 2 picked · head to head
GPT-5 Chat vs gpt-oss-20b
Side by side · benchmarks, pricing, and signals you can act on.
Winner summary
GPT-5 Chat wins on 6/6 benchmarks
GPT-5 Chat wins 6 of 6 shared benchmarks. Leads in arena · knowledge · language.
Category leads
arena·GPT-5 Chatknowledge·GPT-5 Chatlanguage·GPT-5 Chatmath·GPT-5 Chatreasoning·GPT-5 Chat
Hype vs Reality
Attention vs performance
GPT-5 Chat
#1 by perf·#1 by attention
gpt-oss-20b
#22 by perf·no signal
Best value
gpt-oss-20b
54.5x better value than GPT-5 Chat
GPT-5 Chat
14.6 pts/$
$5.63/M
gpt-oss-20b
792.9 pts/$
$0.09/M
Vendor risk
Who is behind the model
OpenAI
$840.0B·Tier 1
OpenAI
$840.0B·Tier 1
Head to head
6 benchmarks · 2 models
GPT-5 Chatgpt-oss-20b
Chatbot Arena Elo · Overall
GPT-5 Chat leads by +108.3
GPT-5 Chat
1426.0
gpt-oss-20b
1317.7
HELM · GPQA
GPT-5 Chat leads by +19.7
GPT-5 Chat
79.1
gpt-oss-20b
59.4
HELM · IFEval
GPT-5 Chat leads by +14.3
GPT-5 Chat
87.5
gpt-oss-20b
73.2
HELM · MMLU-Pro
GPT-5 Chat leads by +12.3
GPT-5 Chat
86.3
gpt-oss-20b
74.0
HELM · Omni-MATH
GPT-5 Chat leads by +8.2
GPT-5 Chat
64.7
gpt-oss-20b
56.5
HELM · WildBench
GPT-5 Chat leads by +12.0
GPT-5 Chat
85.7
gpt-oss-20b
73.7
Full benchmark table
| Benchmark | GPT-5 Chat | gpt-oss-20b |
|---|---|---|
Chatbot Arena Elo · Overall | 1426.0 | 1317.7 |
HELM · GPQA | 79.1 | 59.4 |
HELM · IFEval | 87.5 | 73.2 |
HELM · MMLU-Pro | 86.3 | 74.0 |
HELM · Omni-MATH | 64.7 | 56.5 |
HELM · WildBench | 85.7 | 73.7 |
Pricing · per 1M tokens · projected $/mo at 10M tokens
| Model | Input | Output | Context | Projected $/mo |
|---|---|---|---|---|
| GPT-5 Chat | $1.25 | $10.00 | 128K tokens (~64 books) | $34.38 |
| gpt-oss-20b | $0.03 | $0.14 | 131K tokens (~66 books) | $0.57 |