ModelRefs / Claude Sonnet 4.5 vs o3 Pro
Claude Sonnet 4.5 vs o3 Pro
Claude Sonnet 4.5 vs o3 Pro: 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 Pro: o3 Pro is OpenAI's highest-capability reasoning model, applying extended compute at inference time to solve complex scientific, mathematical, and programming problems. It achieved the highest published scores on ARC-AGI-2 and competitive programming benchmarks at its June 2025 release.
Context window: Claude Sonnet 4.5 accepts up to 200,000 tokens, o3 Pro up to 200,000. Confirm the limit for your specific deployment channel before relying on it.
Claude Sonnet 4.5 vs o3 Pro at a glance
| Attribute | Claude Sonnet 4.5 | o3 Pro |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Released | 2025-09-29 | 2025-06-10 |
| Context window | 200,000 tokens | 200,000 tokens |
| Input price | $3/M tokens | $20/M tokens |
| Output price | $15/M tokens | $80/M tokens |
| Licence | Proprietary | Proprietary |
| Self-hostable | No, hosted only | No, hosted only |
| Modalities | text, vision | text, vision |
Where they differ most
- Coding: Claude Sonnet 4.5 77%, o3 Pro 85%. o3 Pro 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 Pro.
Frequently asked questions
Which is better, Claude Sonnet 4.5 or o3 Pro?
Claude Sonnet 4.5 and o3 Pro target different workloads — see the benchmark and pricing tables for a side-by-side answer.
Is Claude Sonnet 4.5 cheaper than o3 Pro?
Compare $0.00300 vs $0.0200 on this page.