GPT-5.5 vs Grok 4.3
Wins 6 of 8 areas
Coding · Agents · Reasoning · Images and charts · Math · Long documents
Wins 0 of 8 areas
—
GPT-5.5 is the stronger all-rounder.Grok 4.3 is cheaper.
Scores updated · 33 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.
- CodingWriting and fixing software60GPT-5.56 of 6 tests
- AgentsCarrying out multi-step tasks on its own50GPT-5.55 of 5 tests
- ReasoningHard problems that need careful thinking40GPT-5.54 of 4 tests
- Images and chartsUnderstanding pictures, charts and video20GPT-5.52 of 2 tests
- MathCompetition and research-level math10GPT-5.51 of 1 test
- Long documentsFinding answers in very long texts10GPT-5.51 of 1 test
- FactsGetting facts right instead of making them up11Even1 each
- Following instructionsDoing exactly what it is asked11Even1 each
Math and long documents 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.
Grok 4.3 costs 89% 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
- Command-line tasks in a real terminalTerminal-Bench 2.1+44.6points ahead
- Fixes real GitHub issues, working as an agentLiveBench · Agentic Coding+35.5points ahead
- Customer-service tasks in a simulated bankτ-Bench V3 · Banking+26.6points ahead
Where Grok 4.3 pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+63.2points ahead
- Follows unfamiliar, precisely checkable instructionsIFBench+5.4points ahead
Every test, side by side
All 33 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 44.684.339.7+44.6
- LiveBench · Agentic CodingGPT-5.5 by 35.55418.5+35.5
- Terminal-Bench HardGPT-5.5 by 22.760.637.9+22.7
- LMArena · WebDevGPT-5.5 by 156 rating points15131357+156 rating
- LiveBench · CodingGPT-5.5 by 12.382.269.9+12.3
- SciCodeGPT-5.5 by 7.555.848.3+7.5
AgentsGPT-5.5
- τ-Bench V3 · BankingGPT-5.5 by 26.63912.4+26.6
- AA ApexAgentsGPT-5.5 by 20.737.717+20.7
- GDPValGPT-5.5 by 20.742.722+20.7
- Terminal-Bench 4.0GPT-5.5 by 14.614.60+14.6
- AA IT-Bench SREGPT-5.5 by 13.145.832.7+13.1
ReasoningGPT-5.5
- CritPtGPT-5.5 by 19.127.18+19.1
- LiveBench · ReasoningGPT-5.5 by 18.989.770.8+18.9
- Humanity's Last ExamGPT-5.5 by 8.645.837.2+8.6
- GPQA DiamondGPT-5.5 by 3.493.590.1+3.4
FactsEven
- AA-Omniscience · Non-hallucinationGrok 4.3 by 63.21174.2+63.2
- AA-Omniscience · AccuracyGPT-5.5 by 23.25834.8+23.2
Images and chartsGPT-5.5
- LMArena · VisionGPT-5.5 by 63 rating points12921229+63 rating
- MMMU-ProGPT-5.5 by 1.879.978.1+1.8
Following instructionsEven
- LiveBench · Instruction FollowingGPT-5.5 by 7.970.762.8+7.9
- IFBenchGrok 4.3 by 5.475.981.3+5.4
Other results10 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.
- Artificial Analysis Coding IndexGPT-5.5 by 32.774.942.2+32.7
- livebench_data_analysisGPT-5.5 by 25.881.655.8+25.8
- AA Agentic IndexGPT-5.5 by 20.137.317.2+20.1
- Finance Agent v2GPT-5.5 by 14.151.837.7+14.1
- livebench_languageGPT-5.5 by 13.887.473.6+13.8
- AA IntelligenceGPT-5.5 by 13.538.424.9+13.5
- τ²-Bench Telecom (AA run)Grok 4.3 by 3.893.997.7+3.8
- ForecastBench with searchGPT-5.5 by 364.361.3+3
- AA-OmniscienceGPT-5.5 by 2.520.518+2.5
- Prophet Arenatie0.10.1tie
Questions people ask
Which is better, GPT-5.5 or Grok 4.3?
GPT-5.5 wins six of the eight areas we test: coding, agents, reasoning, images and charts, math and long documents. Grok 4.3 wins none, but costs 89% less. They are level on facts and following instructions.
Which is better for coding?
GPT-5.5. It wins 6 of the 6 coding tests both models report; Grok 4.3 wins none.
Which is cheaper?
GPT-5.5 costs $5.00 per million input tokens and $30.00 per million output tokens; Grok 4.3 costs $1.25 and $2.50. That makes Grok 4.3 about 89% cheaper for the same work.
How do you compare the two?
We use the 33 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 10 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.