Claude Haiku 4.5 vs K2 Think V2
Wins 4 of 6 areas
Coding · Agents · Facts · Long documents
Wins 2 of 6 areas
Reasoning · Following instructions
Claude Haiku 4.5 is the stronger all-rounder.K2 Think V2 is better at reasoning.
Scores updated · 17 tests both models report · How we compare
Where each one wins
Tests won in each of the six 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.
- CodingWriting and fixing software30Claude Haiku 4.53 of 3 tests
- AgentsCarrying out multi-step tasks on its own20Claude Haiku 4.52 of 2 tests
- FactsGetting facts right instead of making them up10Claude Haiku 4.51 of 2 tests · 1 tie
- Long documentsFinding answers in very long texts10Claude Haiku 4.51 of 1 test
- ReasoningHard problems that need careful thinking01K2 Think V21 of 3 tests · 2 ties
- Following instructionsDoing exactly what it is asked01K2 Think V21 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.
The biggest differences
The tests each model wins by the widest margin, up to three each. Scores are out of 100.
Where Claude Haiku 4.5 pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+43.9points ahead
- Command-line tasks in a real terminalTerminal-Bench 2.1+29.2points ahead
- Hard command-line tasks in a real terminalTerminal-Bench Hard+20.5points ahead
Where K2 Think V2 pulls ahead
- Follows unfamiliar, precisely checkable instructionsIFBench+8.5points ahead
- Graduate-level biology, physics and chemistry questionsGPQA Diamond+4.1points ahead
Every test, side by side
All 17 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingClaude Haiku 4.5
- Terminal-Bench 2.1Claude Haiku 4.5 by 29.244.215+29.2
- Terminal-Bench HardClaude Haiku 4.5 by 20.527.36.8+20.5
- SciCodeClaude Haiku 4.5 by 9.242.233+9.2
AgentsClaude Haiku 4.5
- GDPValClaude Haiku 4.5 by 11.811.80+11.8
- τ-Bench V3 · BankingClaude Haiku 4.5 by 3.99.35.4+3.9
ReasoningK2 Think V2
- GPQA DiamondK2 Think V2 by 4.167.271.3+4.1
- Humanity's Last Examtie10.410.1tie
- CritPttie00tie
FactsClaude Haiku 4.5
- AA-Omniscience · Non-hallucinationClaude Haiku 4.5 by 43.972.728.8+43.9
- AA-Omniscience · Accuracytie1818tie
Following instructionsK2 Think V2
- IFBenchK2 Think V2 by 8.554.362.8+8.5
Other results5 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 Haiku 4.5 by 35.9-4.4-40.3+35.9
- τ²-Bench Telecom (AA run)Claude Haiku 4.5 by 29.354.725.4+29.3
- Artificial Analysis Coding IndexClaude Haiku 4.5 by 22.943.921+22.9
- AA Agentic IndexClaude Haiku 4.5 by 8.510.31.8+8.5
- AA IntelligenceClaude Haiku 4.5 by 5.416.911.5+5.4
Questions people ask
Which is better, Claude Haiku 4.5 or K2 Think V2?
Claude Haiku 4.5 wins four of the six areas where both have results: coding, agents, facts and long documents. K2 Think V2 wins reasoning and following instructions.
Which is better for coding?
Claude Haiku 4.5. It wins 3 of the 3 coding tests both models report; K2 Think V2 wins none.
How do you compare the two?
We use the 17 benchmark tests both models have published scores on. The verdict counts the 12 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 5 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.