GLM-5.1 vs GPT-5.5
Wins 0 of 7 areas
—
Wins 6 of 7 areas
Coding · Agents · Reasoning · Facts · Math · Long documents
GPT-5.5 is the stronger all-rounder.GLM-5.1 is cheaper.
Scores updated · 42 tests both models report · How we compare
Where each one wins
Tests won in each of the seven 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.
- AgentsCarrying out multi-step tasks on its own06GPT-5.56 of 6 tests
- ReasoningHard problems that need careful thinking04GPT-5.54 of 4 tests
- CodingWriting and fixing software03GPT-5.53 of 5 tests · 2 ties
- MathCompetition and research-level math03GPT-5.53 of 3 tests
- FactsGetting facts right instead of making them up12GPT-5.52 of 3 tests
- Long documentsFinding answers in very long texts01GPT-5.51 of 1 test
- Following instructionsDoing exactly what it is asked00Even0 each · 1 tie
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.
GLM-5.1 costs 83% 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-5.5 pulls ahead
- Unpublished advanced math problemsFrontierMath Tiers 1-3 (v2)+48.5points ahead
- Answers hard knowledge questions correctlyAA-Omniscience · Accuracy+34.3points ahead
- Short factual questions, answered correctlySimpleQA Verified+29points ahead
Where GLM-5.1 pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+59.1points ahead
Every test, side by side
All 42 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingGPT-5.5
- Terminal-Bench 2.1GPT-5.5 by 22.561.884.3+22.5
- Terminal-Bench HardGPT-5.5 by 17.443.260.6+17.4
- SciCodeGPT-5.5 by 1144.855.8+11
- LMArena · WebDevtie15081513tie
- SWE-bench Protie58.458.6tie
AgentsGPT-5.5
- τ-Bench V3 · BankingGPT-5.5 by 25.413.639+25.4
- Terminal-Bench 4.0GPT-5.5 by 12.6214.6+12.6
- GDPValGPT-5.5 by 11.73142.7+11.7
- AA IT-Bench SREGPT-5.5 by 5.540.345.8+5.5
- BrowseCompGPT-5.5 by 5.179.384.4+5.1
- MCP AtlasGPT-5.5 by 3.571.875.3+3.5
ReasoningGPT-5.5
- CritPtGPT-5.5 by 22.54.627.1+22.5
- Humanity's Last ExamGPT-5.5 by 15.730.145.8+15.7
- SimpleBenchGPT-5.5 by 13.955.169+13.9
- GPQA DiamondGPT-5.5 by 6.786.893.5+6.7
FactsGPT-5.5
- AA-Omniscience · Non-hallucinationGLM-5.1 by 59.170.111+59.1
- AA-Omniscience · AccuracyGPT-5.5 by 34.323.758+34.3
- SimpleQA VerifiedGPT-5.5 by 293463+29
MathGPT-5.5
- FrontierMath Tiers 1-3 (v2)GPT-5.5 by 48.536.885.3+48.5
- HMMT Feb. 2026GPT-5.5 by 15.982.698.5+15.9
- AIME 2026GPT-5.5 by 4.795.3100+4.7
Other results19 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.
- DeepSWEGPT-5.5 by 521870+52
- GDPval-AA (Elo)GPT-5.5 by 234 rating points15351769+234 rating
- frontiermath_tier_4_v1GPT-5.5 by 22.912.535.4+22.9
- Program BenchGPT-5.5 by 19.950.970.8+19.9
- AA-OmniscienceGPT-5.5 by 19.60.820.5+19.6
- Artificial Analysis Coding IndexGPT-5.5 by 19.155.874.9+19.1
- Tool-DecathlonGPT-5.5 by 14.940.755.6+14.9
- ToolathlonGPT-5.5 by 14.940.755.6+14.9
- Terminal-Bench 2.0GPT-5.5 by 13.76982.7+13.7
- CyberGymGPT-5.5 by 13.168.781.8+13.1
- AA IntelligenceGPT-5.5 by 12.326.138.4+12.3
- AA Agentic IndexGPT-5.5 by 12.125.237.3+12.1
- LiveBenchGPT-5.5 by 10.570.280.7+10.5
- PostTrainBenchGPT-5.5 by 8.320.128.4+8.3
- NL2RepoGPT-5.5 by 842.750.7+8
- Finance Agent v2GPT-5.5 by 744.851.8+7
- τ²-Bench Telecom (AA run)GLM-5.1 by 3.897.793.9+3.8
- HMMT Nov. 2025GPT-5.5 by 2.59496.5+2.5
- HLE (with tools)tie52.352.2tie
Questions people ask
Which is better, GLM-5.1 or GPT-5.5?
GPT-5.5 wins six of the seven areas where both have results: coding, agents, reasoning, facts, math and long documents. GLM-5.1 wins none, but costs 83% less. They are level on following instructions.
Which is better for coding?
GPT-5.5. It wins 3 of the 5 coding tests both models report; GLM-5.1 wins none, and 2 are ties.
Which is cheaper?
GLM-5.1 costs $1.38 per million input tokens and $4.40 per million output tokens; GPT-5.5 costs $5.00 and $30.00. That makes GLM-5.1 about 83% cheaper for the same work.
How do you compare the two?
We use the 42 benchmark tests both models have published scores on. The verdict counts the 23 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 19 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.