OpenAI vs Anthropic API Pricing Comparison (2026): Which LLM Is Actually Cheaper?

A detailed 2026 pricing comparison of OpenAI and Anthropic APIs covering every model tier, caching mechanics, batch processing discounts, long-context surcharges, and hidden costs. OpenAI is generally cheaper at standard rates and dominates the ultra-budget tier with GPT-5.4 Nano and GPT-4.1 Nano, which have no Anthropic equivalents. Both providers now offer 90% prompt caching discounts on flagship models, narrowing Anthropic's previous caching advantage — though Anthropic retains an edge with more granular cache control. Real-world cost scenarios for chatbots, bulk document processing, and RAG apps are included, along with a practical decision guide: choose Anthropic for complex reasoning, agentic workflows, and cache-heavy pipelines; choose OpenAI for ultra-high-volume, batch, and cache-light workloads. A hidden costs checklist covers reasoning token overhead, long-context surcharges, tool use tokens, and Anthropic-specific fees like data residency and web search charges.