Claude Opus 4.8 vs Grok 4.20
Wins 6 of 7 areas
Coding · Agents · Reasoning · Facts · Math · Long documents
Wins 1 of 7 areas
Following instructions
Claude Opus 4.8 is the stronger all-rounder.Grok 4.20 is cheaper and better at following instructions.
Scores updated · 22 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.
- ReasoningHard problems that need careful thinking40Claude Opus 4.84 of 4 tests
- CodingWriting and fixing software20Claude Opus 4.82 of 2 tests
- AgentsCarrying out multi-step tasks on its own20Claude Opus 4.82 of 2 tests
- MathCompetition and research-level math20Claude Opus 4.82 of 2 tests
- FactsGetting facts right instead of making them up21Claude Opus 4.82 of 3 tests
- Long documentsFinding answers in very long texts10Claude Opus 4.81 of 1 test
- Following instructionsDoing exactly what it is asked01Grok 4.201 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 4.20 costs 88% 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 Claude Opus 4.8 pulls ahead
- Extremely hard research-level math problemsFrontierMath Tier 4+39points ahead
- Unpublished advanced math problemsFrontierMath Tiers 1-3 (v2)+35.1points ahead
- Long professional tasks in banking, consulting and lawAA ApexAgents+25.2points ahead
Where Grok 4.20 pulls ahead
- Follows unfamiliar, precisely checkable instructionsIFBench+20.7points ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+16.9points ahead
Every test, side by side
All 22 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingClaude Opus 4.8
- Terminal-Bench HardClaude Opus 4.8 by 17.458.340.9+17.4
- SciCodeClaude Opus 4.8 by 9.754.444.7+9.7
AgentsClaude Opus 4.8
- AA ApexAgentsClaude Opus 4.8 by 25.239.414.2+25.2
- GDPValClaude Opus 4.8 by 20.847.827+20.8
ReasoningClaude Opus 4.8
- Humanity's Last ExamClaude Opus 4.8 by 16.348.732.4+16.3
- CritPtClaude Opus 4.8 by 14.920.96+14.9
- ARC-AGI-2Claude Opus 4.8 by 772.165.1+7
- GPQA DiamondClaude Opus 4.8 by 3.59288.5+3.5
FactsClaude Opus 4.8
- SimpleQA VerifiedClaude Opus 4.8 by 22.85330.2+22.8
- AA-Omniscience · AccuracyClaude Opus 4.8 by 19.948.828.9+19.9
- AA-Omniscience · Non-hallucinationGrok 4.20 by 16.960.777.6+16.9
MathClaude Opus 4.8
- FrontierMath Tier 4Claude Opus 4.8 by 3956.117.1+39
- FrontierMath Tiers 1-3 (v2)Claude Opus 4.8 by 35.18044.9+35.1
Following instructionsGrok 4.20
- IFBenchGrok 4.20 by 20.762.282.9+20.7
Other results7 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 IndexClaude Opus 4.8 by 32.174.342.2+32.1
- AA IntelligenceClaude Opus 4.8 by 16.641.825.2+16.6
- AA-OmniscienceClaude Opus 4.8 by 15.828.812.9+15.8
- HiL-Bench (Tools-allowed)Claude Opus 4.8 by 15.335.320+15.3
- AA Agentic IndexGrok 4.20 by 8.342.650.9+8.3
- ARC-AGI-1Claude Opus 4.8 by 392.589.5+3
- τ²-Bench Telecom (AA run)Grok 4.20 by 2.194.496.5+2.1
Questions people ask
Which is better, Claude Opus 4.8 or Grok 4.20?
Claude Opus 4.8 wins six of the seven areas where both have results: coding, agents, reasoning, facts, math and long documents. Grok 4.20 wins following instructions, and costs 88% less.
Which is better for coding?
Claude Opus 4.8. It wins 2 of the 2 coding tests both models report; Grok 4.20 wins none.
Which is cheaper?
Claude Opus 4.8 costs $5.00 per million input tokens and $25.00 per million output tokens; Grok 4.20 costs $1.25 and $2.50. That makes Grok 4.20 about 88% cheaper for the same work.
How do you compare the two?
We use the 22 benchmark tests both models have published scores on. The verdict counts the 15 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 7 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.