GPT-5.5 vs Grok 4.1 Fast
Wins 8 of 8 areas
Coding · Agents · Reasoning · Facts · Images and charts · Math · Long documents · Following instructions
Wins 0 of 8 areas
—
GPT-5.5 is the stronger all-rounder.Grok 4.1 Fast is cheaper.
Scores updated · 28 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 thinking40GPT-5.54 of 4 tests
- CodingWriting and fixing software30GPT-5.53 of 3 tests
- AgentsCarrying out multi-step tasks on its own20GPT-5.52 of 2 tests
- Images and chartsUnderstanding pictures, charts and video20GPT-5.52 of 2 tests
- MathCompetition and research-level math20GPT-5.52 of 2 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
- Following instructionsDoing exactly what it is asked10GPT-5.51 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.
Grok 4.1 Fast 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-5.5 pulls ahead
- Hard command-line tasks in a real terminalTerminal-Bench Hard+36.4points ahead
- Answers hard knowledge questions correctlyAA-Omniscience · Accuracy+32.9points ahead
- Real work tasks from 44 professionsGDPVal+28.6points ahead
Where Grok 4.1 Fast pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+15.6points ahead
Every test, side by side
All 28 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingGPT-5.5
- Terminal-Bench HardGPT-5.5 by 36.460.624.2+36.4
- LMArena · WebDevGPT-5.5 by 273 rating points15131240+273 rating
- SciCodeGPT-5.5 by 11.655.844.2+11.6
AgentsGPT-5.5
- GDPValGPT-5.5 by 28.642.714.1+28.6
- AA IT-Bench SREGPT-5.5 by 27.945.817.9+27.9
ReasoningGPT-5.5
- Humanity's Last ExamGPT-5.5 by 26.545.819.3+26.5
- CritPtGPT-5.5 by 24.227.12.9+24.2
- SimpleBenchGPT-5.5 by 136956+13
- GPQA DiamondGPT-5.5 by 8.293.585.3+8.2
FactsGPT-5.5
- AA-Omniscience · AccuracyGPT-5.5 by 32.95825.1+32.9
- AA-Omniscience · Non-hallucinationGrok 4.1 Fast by 15.61126.6+15.6
- Vectara HHEM hallucination ratelower is betterGPT-5.5 by 9.99.319.2+9.9
Images and chartsGPT-5.5
- MMMU-ProGPT-5.5 by 16.679.963.3+16.6
- LMArena · VisionGPT-5.5 by 91 rating points12921201+91 rating
MathGPT-5.5
- HMMT Feb. 2026GPT-5.5 by 12.198.586.4+12.1
- AIME 2026GPT-5.5 by 5.810094.2+5.8
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 55.474.919.5+55.4
- AA-OmniscienceGPT-5.5 by 50.420.5-29.9+50.4
- matharena_visual_math_overallGPT-5.5 by 25.994.969+25.9
- AA IntelligenceGPT-5.5 by 1838.420.4+18
- vectara_factual_consistencyGPT-5.5 by 9.990.780.8+9.9
- AA Agentic IndexGPT-5.5 by 4.437.332.9+4.4
- HMMT Nov. 2025GPT-5.5 by 3.296.593.3+3.2
- vectara_avg_summary_lengthGPT-5.5 by 30.1 rating points129.699.5+30.1 rating
- τ²-Bench Telecom (AA run)tie93.993.3tie
- vectara_answer_ratetie10099.7tie
Questions people ask
Which is better, GPT-5.5 or Grok 4.1 Fast?
GPT-5.5 wins all eight areas we test: coding, agents, reasoning, facts, images and charts, math, long documents and following instructions. Grok 4.1 Fast wins none, but costs 98% less.
Which is better for coding?
GPT-5.5. It wins 3 of the 3 coding tests both models report; Grok 4.1 Fast wins none.
Which is cheaper?
GPT-5.5 costs $5.00 per million input tokens and $30.00 per million output tokens; Grok 4.1 Fast costs $0.20 and $0.50. That makes Grok 4.1 Fast about 98% cheaper for the same work.
How do you compare the two?
We use the 28 benchmark tests both models have published scores on. The verdict counts the 18 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.