A.X-K2 vs Claude Opus 4.8
Wins 0 of 5 areas
—
Wins 4 of 5 areas
Coding · Agents · Reasoning · Long documents
Claude Opus 4.8 is the stronger all-rounder.
Scores updated · 15 tests both models report · How we compare
Where each one wins
Tests won in each of the five 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.
- AgentsCarrying out multi-step tasks on its own03Claude Opus 4.83 of 3 tests
- ReasoningHard problems that need careful thinking03Claude Opus 4.83 of 3 tests
- CodingWriting and fixing software02Claude Opus 4.82 of 2 tests
- Long documentsFinding answers in very long texts01Claude Opus 4.81 of 1 test
- FactsGetting facts right instead of making them up11Even1 each
Long documents rests on a single test.
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.
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
- Command-line tasks in a real terminalTerminal-Bench 2.1+45.6points ahead
- Answers hard knowledge questions correctlyAA-Omniscience · Accuracy+30.2points ahead
- Real work tasks from 44 professionsGDPVal+24.6points ahead
Where A.X-K2 pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+6.3points ahead
Every test, side by side
All 15 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingClaude Opus 4.8
- Terminal-Bench 2.1Claude Opus 4.8 by 45.63984.6+45.6
- SciCodeClaude Opus 4.8 by 13.44154.4+13.4
AgentsClaude Opus 4.8
- GDPValClaude Opus 4.8 by 24.623.247.8+24.6
- Terminal-Bench 4.0Claude Opus 4.8 by 21.7021.7+21.7
- τ-Bench V3 · BankingClaude Opus 4.8 by 18.116.134.2+18.1
ReasoningClaude Opus 4.8
- Humanity's Last ExamClaude Opus 4.8 by 19.129.648.7+19.1
- CritPtClaude Opus 4.8 by 128.920.9+12
- GPQA DiamondClaude Opus 4.8 by 6.385.792+6.3
FactsEven
- AA-Omniscience · AccuracyClaude Opus 4.8 by 30.218.648.8+30.2
- AA-Omniscience · Non-hallucinationA.X-K2 by 6.36760.7+6.3
Other results4 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.
- AA-OmniscienceClaude Opus 4.8 by 37-8.228.8+37
- Artificial Analysis Coding IndexClaude Opus 4.8 by 35.538.874.3+35.5
- AA IntelligenceClaude Opus 4.8 by 20.321.541.8+20.3
- AA Agentic IndexClaude Opus 4.8 by 16.925.742.6+16.9
Questions people ask
Which is better, A.X-K2 or Claude Opus 4.8?
Claude Opus 4.8 wins four of the five areas where both have results: coding, agents, reasoning and long documents. A.X-K2 wins none. They are level on facts.
Which is better for coding?
Claude Opus 4.8. It wins 2 of the 2 coding tests both models report; A.X-K2 wins none.
How do you compare the two?
We use the 15 benchmark tests both models have published scores on. The verdict counts the 11 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 4 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.