Opus vs Sonnet vs Haiku: A Cost-vs-Capability Routing Guide

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TrueFoundry AI Gateway delivers ~3–4 ms latency, handles 350+ RPS on 1 vCPU, scales horizontally with ease, and is production-ready, while LiteLLM suffers from high latency, struggles beyond moderate RPS, lacks built-in scaling, and is best for light or prototype workloads.


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Frequently asked questions
What’s the difference between Opus, Sonnet, and Haiku?
They are Claude tiers trading capability for price. Haiku 5.5 is the fastest and cheapest for high-volume tasks; Sonnet 5.5 balances speed and intelligence; Opus 5.5 is the recommended default for most workloads. Fable 5.1 sits above them for the most demanding reasoning. All share a 1M-token context window.
Which Claude model is cheapest?
Haiku 5.5, starting around $0.10 input / $0.50 output per million tokens as of October 2026. Fable 5.1 is the most expensive at $10 / $50. Confirm current rates on Anthropic’s pricing page.
Should I just use the most capable model everywhere?
Usually not — most requests don’t need it, and the price spread from Haiku to Fable is roughly 100x. Route easy, high-volume work to cheaper tiers and reserve the top tiers for hard tasks.
How do I route by task without rewriting my app?
Point the app at a logical model name backed by a tier, or use a gateway’s automatic routing to score each request and pick a tier. The application calls one endpoint; the routing lives in configuration.
Does a bigger context window mean a better model?
Not here — all four tiers share the same 1M-token window. Choose on reasoning depth and latency, not context size.










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