GPT-5.1 vs gpt-oss-20b
Wins 6 of 6 areas
Coding · Agents · Reasoning · Facts · Long documents · Following instructions
Wins 0 of 6 areas
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GPT-5.1 is the stronger all-rounder.gpt-oss-20b is cheaper.
Scores updated · 29 tests both models report · How we compare
Where each one wins
Tests won in each of the six areas where both have results. Each piece is one test, so a longer bar means more evidence; grey means the two scored within a point of each other.
- CodingWriting and fixing software50GPT-5.15 of 5 tests
- AgentsCarrying out multi-step tasks on its own30GPT-5.13 of 3 tests
- ReasoningHard problems that need careful thinking30GPT-5.13 of 3 tests
- FactsGetting facts right instead of making them up20GPT-5.12 of 2 tests
- Long documentsFinding answers in very long texts10GPT-5.11 of 1 test
- Following instructionsDoing exactly what it is asked10GPT-5.11 of 1 test
Long documents and following instructions rest on a single test each.
What it costs
Prices per million tokens, roughly 750,000 words. The bars show the cost of a million tokens read plus a million written.
gpt-oss-20b costs 98% less for the same work.
The biggest differences
The tests each model wins by the widest margin, up to three each. Scores are out of 100.
Where GPT-5.1 pulls ahead
- Reasons across sets of long documentsAA-LCR+45.3points ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+42.2points ahead
- Command-line tasks in a real terminalTerminal-Bench 2.1+38.5points ahead
Where gpt-oss-20b pulls ahead
No clear win on a test scored out of 100.
Every test, side by side
All 29 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingGPT-5.1
- Terminal-Bench 2.1GPT-5.1 by 38.552.413.9+38.5
- Terminal-Bench HardGPT-5.1 by 34.945.510.6+34.9
- LiveCodeBench v6GPT-5.1 by 268761+26
- SWE-bench VerifiedGPT-5.1 by 23.976.352.4+23.9
- SciCodeGPT-5.1 by 4.443.338.9+4.4
AgentsGPT-5.1
- BrowseCompGPT-5.1 by 22.550.828.3+22.5
- GDPValGPT-5.1 by 16.516.50+16.5
- τ-Bench V3 · BankingGPT-5.1 by 8.915.97+8.9
ReasoningGPT-5.1
- GPQA DiamondGPT-5.1 by 18.587.368.8+18.5
- Humanity's Last ExamGPT-5.1 by 17.528.511+17.5
- CritPtGPT-5.1 by 3.54.91.4+3.5
FactsGPT-5.1
- AA-Omniscience · Non-hallucinationGPT-5.1 by 42.248.15.9+42.2
- AA-Omniscience · AccuracyGPT-5.1 by 21.737.716+21.7
Other results14 tests, not counted
Tests outside the eight areas. They are not counted above: several are summary scores built from other tests, or the same test under another name.
- AA-OmniscienceGPT-5.1 by 68.45.4-63+68.4
- τ²-BenchGPT-5.1 by 3582.747.7+35
- Artificial Analysis Coding IndexGPT-5.1 by 28.749.420.7+28.7
- τ²-Bench Telecom (AA run)GPT-5.1 by 21.781.960.2+21.7
- HMMT Feb. 2025GPT-5.1 by 19.696.376.7+19.6
- AA IntelligenceGPT-5.1 by 15.724.79+15.7
- XSTestGPT-5.1 by 1198.287.2+11
- MMLU-ProGPT-5.1 by 10.68776.4+10.6
- bbqgpt-oss-20b by 888.796.7+8
- AIME 2025GPT-5.1 by 4.89489.2+4.8
- HarmBenchgpt-oss-20b by 1.197.698.7+1.1
- AIR-Bench 2024tie86.286tie
- anthropic_red_teamtie99.599.7tie
- simple_safety_teststie99.8100tie
Questions people ask
Which is better, GPT-5.1 or gpt-oss-20b?
GPT-5.1 wins all six areas where both have results: coding, agents, reasoning, facts, long documents and following instructions. gpt-oss-20b wins none, but costs 98% less.
Which is better for coding?
GPT-5.1. It wins 5 of the 5 coding tests both models report; gpt-oss-20b wins none.
Which is cheaper?
GPT-5.1 costs $1.25 per million input tokens and $10.00 per million output tokens; gpt-oss-20b costs $0.07 and $0.18. That makes gpt-oss-20b about 98% cheaper for the same work.
How do you compare the two?
We use the 29 benchmark tests both models have published scores on. The verdict counts the 15 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 14 are listed but not counted, because several are summary scores or repeat a test. Each score is the one shown on the model's own page.