GLM-5.3-Flash vs GPT-5.5
Wins 1 of 8 areas
Agents
Wins 5 of 8 areas
Reasoning · Facts · Math · Long documents · Following instructions
GPT-5.5 is the stronger all-rounder.GLM-5.3-Flash is cheaper and better at agents.
Scores updated · 40 tests both models report · How we compare
Where each one wins
Tests won in each of the eight areas we test. Each piece is one test, so a longer bar means more evidence; grey means the two scored within a point of each other.
- ReasoningHard problems that need careful thinking05GPT-5.55 of 5 tests
- 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 asked01GPT-5.51 of 1 test
- AgentsCarrying out multi-step tasks on its own42GLM-5.3-Flash4 of 6 tests
- CodingWriting and fixing software22Even2 each · 1 tie
- Images and chartsUnderstanding pictures, charts and video00Even0 each · 1 tie
Images and charts, 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-5.3-Flash costs 98% less for the same work.
The biggest differences
The three tests each model wins by the widest margin. Scores are out of 100.
Where GPT-5.5 pulls ahead
- Completes tasks by operating a computer desktopOSWorld-Verified+63.9points ahead
- Extremely hard research-level math problemsFrontierMath Tier 4+55.4points ahead
- Short factual questions, answered correctlySimpleQA Verified+31points ahead
Where GLM-5.3-Flash pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+61.4points ahead
- Complex command-line tasks across many fieldsTerminal-Bench 4.0+18.2points ahead
- Real work tasks from 44 professionsGDPVal+14.7points ahead
Every test, side by side
All 40 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingEven
- LMArena · WebDevGLM-5.3-Flash by 122 rating points16091487+122 rating
- SciCodeGPT-5.5 by 4.251.655.8+4.2
- LiveBench · CodingGPT-5.5 by 3.27982.2+3.2
- LiveBench · Agentic CodingGLM-5.3-Flash by 2.856.854+2.8
- Terminal-Bench 2.1tie84.384.3tie
AgentsGLM-5.3-Flash
- OSWorld-VerifiedGPT-5.5 by 63.914.878.7+63.9
- Terminal-Bench 4.0GLM-5.3-Flash by 18.232.814.6+18.2
- GDPValGLM-5.3-Flash by 14.757.242.5+14.7
- BrowseCompGPT-5.5 by 8.47684.4+8.4
- τ-Bench V3 · BankingGLM-5.3-Flash by 8.247.239+8.2
- AA IT-Bench SREGLM-5.3-Flash by 5.451.245.8+5.4
ReasoningGPT-5.5
- ARC-AGI-2GPT-5.5 by 19.265.885+19.2
- LiveBench · ReasoningGPT-5.5 by 12.177.689.7+12.1
- CritPtGPT-5.5 by 11.715.427.1+11.7
- Humanity's Last ExamGPT-5.5 by 5.939.945.8+5.9
- GPQA DiamondGPT-5.5 by 2.391.293.5+2.3
FactsGPT-5.5
- AA-Omniscience · Non-hallucinationGLM-5.3-Flash by 61.472.411+61.4
- SimpleQA VerifiedGPT-5.5 by 313263+31
- AA-Omniscience · AccuracyGPT-5.5 by 30.527.558+30.5
MathGPT-5.5
- FrontierMath Tier 4GPT-5.5 by 55.417.172.5+55.4
- FrontierMath Tiers 1-3 (v2)GPT-5.5 by 29.555.885.3+29.5
- LiveBench · MathematicsGPT-5.5 by 14.781.295.9+14.7
Following instructionsGPT-5.5
- LiveBench · Instruction FollowingGPT-5.5 by 17.952.870.7+17.9
Other results15 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.
- ToolathlonGLM-5.3-Flash by 22.878.455.6+22.8
- JobBenchGLM-5.3-Flash by 22.460.738.3+22.4
- AA Agentic IndexGLM-5.3-Flash by 13.951.237.3+13.9
- AA-OmniscienceGPT-5.5 by 137.520.5+13
- livebench_languageGPT-5.5 by 10.177.387.4+10.1
- GDP (Surge AI)GPT-5.5 by 9.515.424.9+9.5
- OfficeQA ProGLM-5.3-Flash by 8.362.454.1+8.3
- NL2RepoGLM-5.3-Flash by 5.656.350.7+5.6
- livebench_data_analysisGPT-5.5 by 5.276.481.6+5.2
- ARC-AGI-1GPT-5.5 by 49195+4
- DeepSWE 1.1GPT-5.5 by 3.663.467+3.6
- AA IntelligenceGLM-5.3-Flash by 3.441.838.4+3.4
- Artificial Analysis Coding IndexGPT-5.5 by 3.471.574.9+3.4
- BabyVisionGPT-5.5 by 2.553.455.9+2.5
- Agents' Last Examtie26.326.6tie
Questions people ask
Which is better, GLM-5.3-Flash or GPT-5.5?
GPT-5.5 wins five of the eight areas we test: reasoning, facts, math, long documents and following instructions. GLM-5.3-Flash wins agents, and costs 98% less. They are level on coding and images and charts.
Which is better for coding?
Neither. They win 2 coding tests each of the 5 both models report, and 1 is a tie.
Which is cheaper?
GLM-5.3-Flash costs $0.15 per million input tokens and $0.50 per million output tokens; GPT-5.5 costs $5.00 and $30.00. That makes GLM-5.3-Flash about 98% cheaper for the same work.
How do you compare the two?
We use the 40 benchmark tests both models have published scores on. The verdict counts the 25 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 15 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.