Claude Haiku 4.5 vs GPT-5.4

Across our 12-test suite, the two models split wins with many ties. In our testing: Claude Haiku 4.5 wins tool_calling (5 vs 4) and classification (4 vs 3) — Haiku is tied for 1st in tool_calling ("tied for 1st with 16 others") and tied for 1st in classification ("tied for 1st with 29 others"), meaning it selects functions and fills arguments more reliably in real agent workflows and routes/categorizes inputs better. GPT-5.4 wins structured_output (5 vs 4), constrained_rewriting (4 vs 3), and safety_calibration (5 vs 2). GPT-5.4 ranks tied for 1st on structured_output ("tied for 1st with 24 others"), ranks 6th on constrained_rewriting, and is tied for 1st on safety_calibration — important when strict JSON/schema adherence, hard-length compression, or conservative refusals are required. They tie on strategic_analysis (both 5), creative_problem_solving (both 4), faithfulness (both 5), long_context (both 5), persona_consistency (both 5), agentic_planning (both 5), and multilingual (both 5), so for deep reasoning, long-context recall, persona maintenance and non-English output both models perform equivalently in our tests. Supplementary external benchmarks favor GPT-5.4: on SWE-bench Verified (Epoch AI) it scores 76.9% (rank 2 of 12) and on AIME 2025 (Epoch AI) it scores 95.3% (rank 3 of 23), which supports its edge on structured and constrained math/coding-style tasks.

Costs per payload (assumes input+output tokens are split 50/50): Claude Haiku 4.5 charges input $1 + output $5 per mTok = $6/mTok; GPT-5.4 charges input $2.5 + output $15 = $17.5/mTok. At 1M tokens/month (1,000 mTok): Haiku ≈ $6,000 vs GPT-5.4 ≈ $17,500. At 10M tokens: Haiku ≈ $60,000 vs GPT-5.4 ≈ $175,000. At 100M tokens: Haiku ≈ $600,000 vs GPT-5.4 ≈ $1,750,000. Who should care: high-volume apps (chatbots, customer support, SaaS features) will see multi-hundred-thousand-dollar differences; startups and cost-sensitive deployments should favor Haiku 4.5, while organizations prioritizing structured output/safety should budget for GPT-5.4. (All per-token rates taken from the payload: Claude Haiku 4.5 input $1 / output $5 per mTok; GPT-5.4 input $2.5 / output $15 per mTok.)

Choose Claude Haiku 4.5 if you need a cost-efficient model with strong tool calling, classification, long-context capability (200k context window), and equivalent performance on strategic analysis, faithfulness, multilingual, and persona consistency — ideal for high-volume chatbots, agentic apps, and production integrations that must minimize token spend. Choose GPT-5.4 if you require best-in-class structured output (JSON/schema), constrained rewriting, or stricter safety calibration, and if you need a 1M+ token context window; budget for roughly 3x higher per-token costs but gain stronger safety/format guarantees and higher external scores on SWE-bench Verified and AIME 2025.