GPT-5.5 vs Grok4.5
Wins 4 of 8 areas
Reasoning · Facts · Math · Long documents
Wins 2 of 8 areas
Coding · Agents
GPT-5.5 wins more areas, narrowly.Grok4.5 is cheaper and better at coding.
Scores updated · 37 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 thinking41GPT-5.54 of 7 tests · 2 ties
- MathCompetition and research-level math30GPT-5.53 of 3 tests
- FactsGetting facts right instead of making them up21GPT-5.52 of 3 tests
- Long documentsFinding answers in very long texts10GPT-5.51 of 1 test
- CodingWriting and fixing software23Grok4.53 of 6 tests · 1 tie
- AgentsCarrying out multi-step tasks on its own12Grok4.52 of 3 tests
- Images and chartsUnderstanding pictures, charts and video00Even0 each · 2 ties
- 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.
Grok4.5 costs 77% 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
- Extremely hard research-level math problemsFrontierMath Tier 4+48.1points ahead
- Abstract visual puzzles that people can solveARC-AGI-2+32.4points ahead
- Unpublished advanced math problemsFrontierMath Tiers 1-3 (v2)+28.1points ahead
Where Grok4.5 pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+34.9points ahead
- Long, multi-file coding tasks in real codebasesSWE-bench Pro+6.1points ahead
- Customer-service tasks in a simulated bankτ-Bench V3 · Banking+3.1points ahead
Every test, side by side
All 37 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingGrok4.5
- LiveBench · CodingGPT-5.5 by 13.682.268.6+13.6
- SWE-bench ProGrok4.5 by 6.158.664.7+6.1
- LMArena · WebDevGrok4.5 by 40 rating points15131553+40 rating
- Terminal-Bench 2.1GPT-5.5 by 2.784.381.6+2.7
- LiveBench · Agentic CodingGrok4.5 by 2.55456.5+2.5
- SciCodetie55.855tie
AgentsGrok4.5
- Terminal-Bench 4.0GPT-5.5 by 414.610.6+4
- τ-Bench V3 · BankingGrok4.5 by 3.13942.1+3.1
- GDPValGrok4.5 by 1.842.744.5+1.8
ReasoningGPT-5.5
- ARC-AGI-2GPT-5.5 by 32.48552.6+32.4
- CritPtGPT-5.5 by 11.727.115.4+11.7
- Humanity's Last ExamGPT-5.5 by 3.145.842.7+3.1
- LiveBench · ReasoningGPT-5.5 by 2.589.787.2+2.5
- SimpleBenchGrok4.5 by 16970+1
- GPQA Diamondtie93.593.1tie
- ARC-AGI-3tie0.40.3tie
FactsGPT-5.5
- AA-Omniscience · Non-hallucinationGrok4.5 by 34.91145.9+34.9
- SimpleQA VerifiedGPT-5.5 by 14.76348.3+14.7
- AA-Omniscience · AccuracyGPT-5.5 by 6.45851.5+6.4
Images and chartsEven
- MMMU-Protie79.980.4tie
- LMArena · Visiontie12921288tie
MathGPT-5.5
- FrontierMath Tier 4GPT-5.5 by 48.172.524.4+48.1
- FrontierMath Tiers 1-3 (v2)GPT-5.5 by 28.185.357.2+28.1
- LiveBench · MathematicsGPT-5.5 by 5.195.990.8+5.1
Following instructionsEven
- LiveBench · Instruction Followingtie70.771.5tie
Other results11 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 177053+17
- SWE-MarathonGrok4.5 by 171229+17
- DeepSWE 1.1GPT-5.5 by 136754+13
- ARC-AGI-1GPT-5.5 by 9.39585.7+9.3
- livebench_data_analysisGPT-5.5 by 8.681.673+8.6
- AA Agentic IndexGrok4.5 by 4.837.342.1+4.8
- AA-OmniscienceGrok4.5 by 4.820.525.3+4.8
- livebench_languageGPT-5.5 by 4.687.482.8+4.6
- GDPval-AA v2 EloGrok4.5 by 44 rating points14911535+44 rating
- Artificial Analysis Coding IndexGPT-5.5 by 2.574.972.4+2.5
- AA Intelligencetie38.438.8tie
Questions people ask
Which is better, GPT-5.5 or Grok4.5?
GPT-5.5 wins four of the eight areas we test: reasoning, facts, math and long documents. Grok4.5 wins coding and agents, and costs 77% less. They are level on images and charts and following instructions.
Which is better for coding?
Grok4.5. It wins 3 of the 6 coding tests both models report; GPT-5.5 wins 2, and 1 is a tie.
Which is cheaper?
GPT-5.5 costs $5.00 per million input tokens and $30.00 per million output tokens; Grok4.5 costs $2.00 and $6.00. That makes Grok4.5 about 77% cheaper for the same work.
How do you compare the two?
We use the 37 benchmark tests both models have published scores on. The verdict counts the 26 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 11 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.