Claude Haiku 4.5 vs Claude Sonnet 4.6 for Writing
Claude Sonnet 4.6 is the better choice for Writing. In our testing Sonnet scores 4.0 on the Writing task versus Claude Haiku 4.5's 3.5 (rank 6 of 52 vs rank 29 of 52). Sonnet outperforms Haiku on creative_problem_solving (5 vs 4) and safety_calibration (5 vs 2), and offers a far larger context window (1,000,000 vs 200,000 tokens) and higher max output (128,000 vs 64,000). Haiku is materially cheaper (input/output cost per mTok 1/5 vs Sonnet 3/15) and still matches Sonnet on persona_consistency, faithfulness, long_context (both scored 5) and structured_output (both 4), but the 0.5 point Writing advantage, stronger creativity, and safety profile make Sonnet the definitive winner for Writing tasks in our benchmarks.
anthropic
Claude Haiku 4.5
Benchmark Scores
External Benchmarks
Pricing
Input
$1.00/MTok
Output
$5.00/MTok
modelpicker.net
anthropic
Claude Sonnet 4.6
Benchmark Scores
External Benchmarks
Pricing
Input
$3.00/MTok
Output
$15.00/MTok
modelpicker.net
Task Analysis
What Writing demands: blog posts, marketing copy, and content creation require idea generation, tone/persona control, faithful adherence to briefs, trimming or compressing copy (constrained rewriting), and handling long drafts or content histories. In the absence of an external benchmark, we base the verdict on our internal task score (Writing: Sonnet 4.0 vs Haiku 3.5) and the underlying component tests. Relevant internal signals: creative_problem_solving (Sonnet 5 vs Haiku 4) measures ideation quality; constrained_rewriting (both 3) measures performance under strict length limits; persona_consistency and faithfulness (both 5) show both models maintain voice and avoid hallucination; long_context (both 5) and max output tokens show both can handle long documents, with Sonnet's 1,000,000-token window and 128,000 max output enabling larger projects. Safety_calibration (Sonnet 5 vs Haiku 2) matters for marketing/legal compliance and sensitive content gating. Note: our ranking follows the same averaged benchmark methodology used across models (average of the task tests); within tied score tiers models are sorted by output cost in our listings.
Practical Examples
Where Claude Sonnet 4.6 shines for Writing: - Marketing ideation and high-volume creative briefs: Sonnet's creative_problem_solving 5 vs Haiku 4 yields more non-obvious, specific ideas in our tests. - Long-form content and multi-draft books: Sonnet's 1,000,000 token context and 128,000 max output tokens let you work with larger source material in a single session. - Compliance-sensitive campaigns: Sonnet's safety_calibration 5 vs Haiku 2 makes it better at refusing disallowed prompts while permitting legitimate copy. Where Claude Haiku 4.5 shines for Writing: - Cost-sensitive content generation at scale: Haiku's input/output cost per mTok are 1 and 5 vs Sonnet's 3 and 15 (use Haiku when budget per token matters). - Fast, efficient production of consistent brand voice: Haiku still scores 5 on persona_consistency and 5 on faithfulness, so it reliably maintains tone and sticks to briefs. Shared strengths (both models): structured_output 4 (JSON/format adherence), tool_calling 5, and long_context 5 — both can deliver structured copy and handle multi-part workflows, but Sonnet offers stronger ideation and safety.
Bottom Line
For Writing, choose Claude Haiku 4.5 if you need lower per-token cost (input/output mTok: 1/5) and high-quality, faithful brand-voice output at scale. Choose Claude Sonnet 4.6 if you prioritize creativity, safety, and handling very large drafts—Sonnet scores 4.0 vs Haiku 3.5 on the Writing task, with creative_problem_solving 5 vs 4 and safety_calibration 5 vs 2.
How We Test
We test every model against our 12-benchmark suite covering tool calling, agentic planning, creative problem solving, safety calibration, and more. Each test is scored 1–5 by an LLM judge. Read our full methodology.