ModelRefs / Claude Sonnet 4.5 vs o3
Claude Sonnet 4.5 vs o3
Claude Sonnet 4.5 vs o3: side-by-side benchmarks, pricing, context windows, coding ability and deployment. Pick the right model for your stack.
Overview
Claude Sonnet 4.5: Claude Sonnet 4.5 is Anthropic's balanced frontier model, designed for complex reasoning, coding, and agentic tasks while maintaining production-grade speed. It builds on the Claude 4 family's emphasis on honesty and reduced hallucination rates.
o3: o3 is OpenAI's April 2025 reasoning model, applying deliberate chain-of-thought computation at inference time to mathematics, science and competitive programming tasks, and the release that brought OpenAI's scalable test-time compute approach to its production API. OpenAI has since deprecated it, scheduling the o3-2025-04-16 snapshot to shut down on 11 December 2026 with gpt-5.6-sol as the replacement.
Context window: Claude Sonnet 4.5 accepts up to 200,000 tokens, o3 up to 200,000. Confirm the limit for your specific deployment channel before relying on it.
Claude Sonnet 4.5 vs o3 at a glance
| Attribute | Claude Sonnet 4.5 | o3 |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Released | 2025-09-29 | 2025-04-16 |
| Context window | 200,000 tokens | 200,000 tokens |
| Input price | $3/M tokens | $10/M tokens |
| Output price | $15/M tokens | $40/M tokens |
| Licence | Proprietary | Proprietary |
| Self-hostable | No, hosted only | No, hosted only |
| Modalities | text, vision | text, vision |
Where they differ most
- Cost Efficiency: Claude Sonnet 4.5 37%, o3 13%. Claude Sonnet 4.5 leads on this dimension.
Capability scores are ModelRefs' own derived signals, not vendor claims or benchmark results. Validate against your own workload before relying on them.
Continue your research
Use these connected ModelRefs sections to compare alternatives, inspect implementation paths, and review the evidence and governance boundaries relevant to Claude Sonnet 4.5 vs o3.
Frequently asked questions
Which is better, Claude Sonnet 4.5 or o3?
Claude Sonnet 4.5 and o3 target different workloads — see the benchmark and pricing tables for a side-by-side answer.
Is Claude Sonnet 4.5 cheaper than o3?
Compare $0.00300 vs $0.0100 on this page.